Service Manual ESIDENTIAL FAN OIL UNITS ancels: SM03-4 SM03-5 6-99 TABLE OF ONTENTS Page SAFETY ONSIDEATIONS... INTODUTION... UNIT IDENTIFIATION... PODUT OFFEIN...4 FAN MOTO SPEED TAPS...4 FA4A, FB4A, F4B, FFD, FH4A, AND FX4A IUIT BOAD FUNTION AND TOUBLESHOOTIN ES03003-00 and -0 PB...-7 Printed ircuit Board omponent Layout and Description... Unit Functions... Troubleshooting PB...5 IUIT BOAD FUNTION AND TOUBLESHOOTIN HK6A00 and HK6A003 PB...8-9 Printed ircuit Board omponent Layout and Description...8 PB omponent Functions...9 Troubleshooting PB... ELETI HEATE FUNTION AND TOUBLESHOOTIN...9 Description of Electric Heater omponents...9 Troubleshooting KFA, KFB, KF, and KFD Series Electric Heaters...0 FAN OIL DESIPTION AND TOUBLESHOOTIN FK4B...0-7 Integrated ontrols and Motor (IM)...0 PB Layout and Description...0 Sequence of Operation... Easy Select onfiguration Taps... Troubleshooting PB...4 Troubleshooting IM...6 ondensed Version of Troubleshooting FK4B Motor and ontrols...6 Accessories...7 FAN OIL DESIPTION AND TOUBLESHOOTIN FK4, FV4A...8-34 Integrated ontrols and Motor (IM)...8 PB Layout and Description...8 Sequence of Operation...8 Easy Select onfiguration Taps...30 Troubleshooting PB...3 Troubleshooting IM...34 ondensed Version of Troubleshooting FK4, FV4A Motor and ontrols...34 Accessories...34 THEMOSTATI EXPANSION VALVES (TXV)...35 Problems Affecting TXV...36 PISTON BODY LEANIN O EPLAEMENT...36 LIQUID TUBE STAINE...36 FA, FB, F, FK OIL/ONDENSATE PAN EMOVAL AND EPLAEMENT...36 A-oil Units...36 Slope oil Units...37 FX, FV OIL/ONDENSATE PAN EMOVAL AND EPLAEMENT...38 Fig. Typical Fan oil A9803 AE AND MAINTENANE...39 Filter Assembly...39 ooling oil, Drain Pan, and ondensate Drain...39 Blower Motor and Wheel...39 FFA/FFB/FF SEVIE AND TOUBLESHOOTIN...40-4 Fan Motor...40 Electric Heater Service...40 leaning or eplacing efrigerant Flow-ontrol Device...40 Liquid Tube Strainer...40 Sequence of Operation...40 are and Maintenance...40 FD3A SEVIE AND TOUBLESHOOTIN...44-45 Fan Motor...44 Electric Heater Service...44 leaning or eplacing efrigerant Flow-ontrol Device...44 Liquid Tube Strainer...44 are and Maintenance...45 F3A SEVIE AND TOUBLESHOOTIN...45-46 Service...45 Maintenance...46 FA4A, FB4A, F4B, FX4A SMAT HEAT IUIT BOAD FUNTION AND TOUBLESHOOTIN..46-50 PB omponent Layout, Description, and Function...46 Unit Functions...46 Smart Heat Operation...47 Electrical Operating Sequences and Troubleshooting...48 PUON (-40A) QUIK EFEENE UIDE...50
This symbol indicates a change since the last issue. SAFETY ONSIDEATIONS Improper installation, adjustment, alteration, service, maintenance, or use can cause explosion, fire, electrical shock, or other conditions which may cause personal injury or property damage. onsult a qualified installer, service agency, or your distributor or branch for information or assistance. The qualified installer or agency must use factory-authorized kits or accessories when modifying this product. efer to the individual installation instructions packaged with the kits or accessories for detailed information. Follow all safety codes. Wear safety glasses and work gloves. Use quenching cloth for brazing operations. Have fire extinguisher available. ead these instructions thoroughly and follow all warnings or cautions attached to the unit. onsult local building codes and National Electrical ode (NE) for special installation requirements. It is important to recognize safety information. This is the safety-alert symbol. When you see this symbol on the unit or in instructions and manuals, be alert to the potential for personal injury. Understand the signal words DANE, WANIN, and AU- TION. These words are used with the safety-alert symbol. DAN- E identifies the most serious hazards which will result in severe personal injury or death. WANIN signifies hazards which could result in personal injury or death. AUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage. AUTION: Puron (-40A) systems operate at higher pressures than - systems. Do not use - service equipment or components on -40A equipment. Ensure service equipment is rated for -40A. INTODUTION The "F" series fan coil units are designed for flexibility in a variety of applications, meeting upflow, horizontal, or downflow requirements. Units are available in -/ through 5 ton nominal cooling capacities. Factory-authorized, field-installed electric heater packages are available in 3 through 30 kilowatts. WANIN: Before installing or servicing fan coil, always turn off all power to unit. There may be more than disconnect switch. Turn off accessory heater power if applicable. Electrical shock can cause personal injury or death. UNIT IDENTIFIATION The 6 position numbering chart allows identification of all available fan coil units. (See Fig..) FA4A, FB4A, F4B, FFD, FH4A, AND FX4A IUIT BOAD FUNTION AND TOUBLESHOOTIN ES030003-00 and -0 PB This section of the service manual describes the ESO30003-00 and -0 PB by examining the functional operation of the PB components. I. PINTED IUIT BOAD (PB) OMPONENT LAYOUT AND DESIPTION Layout of the actual PB is depicted in Fig. 3A.. The low-voltage stripped leads are used to connect the 4-v side of transformer to indoor thermostat and outdoor section.. A 5-amp fuse is used to protect the low-voltage transformer secondary. 3. The fan relay is controlled by thermostat and turns fan on and off. 4. A plug is used as the connection for PB power and electric heaters. Note the pin numbers on plug. 5. A time-delay relay circuit keeps fan motor running for approximately 90 sec after is de-energized. The timedelay can be defeated by cutting jumper JW. II. UNIT FUNTIONS A. Transformer. Proper Wiring of Transformer Primary or High Side Yellow wire from Molex plug is wired to terminal on transformer and black wire from PB relay (normallyopen) terminal is wired to 08v or 30v terminal on transformer. Units are factory wired at 30v terminal.. Proper Wiring of Transformer Secondary or 4-v Side ed wire of transformer is wired to T terminal on PB and brown wire of transformer is wired to terminal on PB. NOTE: T terminal on PB is used to protect transformer. T terminal is connected through the fuse to terminal on PB. B. Indoor Fan. Wiring (See Fig. 3B for FFD typical wiring diagram.) Indoor fan motor yellow lead is wired to terminal on transformer. The red, blue, or black speed lead is wired to SPT terminal on fan relay part of PB. Units are factory wired on medium speed (blue lead connected). NOTE: Unused fan speed leads must be capped or taped off to prevent direct short to cabinet surface.. Functional ontrol a. Thermostat and elay ontrol When thermostat calls for the fan in cooling, heat pump, heating, or fan-only mode, a 4-vac signal is sent to relay. This causes the relay to close its normally-open contacts, turning on fan. When thermostat no longer calls for the fan, the signal sent to relay is turned off and relay opens causing fan to turn off after a 90-sec fan-off delay. b. Sequencer/Electric Heat elay Interlock The fan will also operate whenever there is a call for electric heat, even if fan relay is not energized. This happens because fan is interlocked with first stage of electric heat through the normally-closed contact of fan relay. NOTE: The fan interlock is only connected to first stage electric heat W. W3 and E do not contain an interlock with fan. See outdoor thermostat Installation Instructions when electric heat staging is desired.. Electric Heat NOTE: Models FFA/FFB/FF use sequencers for electric heat. Model FFD uses D rectified relays for electric heat. (See Fig. 3.) When thermostat calls for electric heat, a 4-vac signal is sent to sequencer/heat relay through W, causing first stage to turn on. W3 and E also receive signal if wired in with W. The signal sent to W causes first stage to turn on. If W3 and E are not wired to W, the sequencers/heat relays can be controlled individually to stage additional electric heat. The sequence control is described in the following section:
3 4 5 6 7 8 9 0 3 4 5 6 Type of Unit Airflow oil Type Variations F - Fan oil - Upflow - Downflow 3 - Horizontal 4 - Multipoise 5 - Upflow/Downflow 6th Position Fan oil A - Standard B - Modular F - Single Piece Minor Series A - Standard Unit A - Original Unit Specifics Major Series Electrical ooling Size Variations nd Position Fan oil A - N B - Standard - Deluxe D - Furred in, ased E - Furred in, Uncased F - Through the Wall - ommercial H - Standard Electric Furnace J - Standard Hot Water K - IM Motor, High Efficiency V - IM Motor, Puron -40A X - Standard, Puron -40A A - Original B - Second Series 5th Position Fan oil A - 5--60 N - 08/30--60 S - 30--50 08 ( Ton) 04 ( Ton) 00 (Multi Tons) 00 (Multi Tons) Etc. Heating Size (KW) A - ommon Unit 0th, th, th Positions Fan oil 005 00 Etc. Fig. Fan oil 6-Position Numbering System A984 3
TABLE PODUT OFFEIN MODEL UNIT SIZE DESIPTION ABINET FA4ANF 08-060 Multipoise Single Piece FB4ANB 04-070 Multipoise Modular FB4ANF 08-060 Multipoise Single Piece FB4ASB 04-060 Multipoise 50 Hz Modular FB4ASF 08-060 Multipoise 50 Hz Single Piece F4BNB 04-070 Multipoise Modular F4BNF 04-060 Multipoise Single Piece FD3ANA 08-030 Horizontal Single Piece FFA/FFB/FF/FFD 08-030 Vertical Single Piece F3ANA 04, 036, 048, 060 Horizontal/Small ommercial Single Piece FH4ANB 003, 004 Multipoise Modular FH4ANF 00-004 Multipoise Single Piece FK4NB 006 Multipoise Modular FK4NF 00-005 Multipoise Single Piece FX4ANF 030-048 Multipoise Single Piece FX4ANB 060 Multipoise Modular FV4ANF 00, 003, 005 Multipoise Single Piece FV4ANB 006 Multipose Modular NOTE: Multipoise units are approved for upflow, downflow, and horizontal left and right applications. MODEL UNIT SIZE TABLE PS FAN MOTO SPEED TAPS NUMBE OF SPEEDS HIH SPEED MEDIUM SPEED LOW SPEED OMMON FA4A 08-036 Black Blue Yellow FA4A 04-060 3 Black Blue ed Yellow FB4A 08-070 3 Black Blue ed Yellow F4B 04-070 3 Black Blue ed Yellow FD3A 08-030 Black ed Yellow FFA/FFB/FF/FFD 08-030 Black ed Violet** F3A 04, 036, 048, 060 * FH4A 00-004 3 Black Blue ed Yellow FX4A 030-060 3 Black Blue ed Yellow *Belt drive. **Yellow on FFD 005-6 005-83-6A 7 3 3 6 Z P-E 94V-0 D D 7 8 0 9 L4006 8 U 6 5 5 4 4 Q K ESO30003-0 HSI T T F 5 AMP N NO SPT JW FAN ELAY LOW VOLTAE FUSE NO PB BLOK WIIN N SPT FUSE TIME DELAY T FAN ELAY Fig. 3A Fan oil Printed-ircuit Board A9700 4
SEE NOTE #8 L SHEMATI DIAAM SEE ATIN PLATE FO VOLTS & HETZ FIELD POWE WIIN OOLIN ONTOLS ELETI HEAT L SEE NOTE # L L DISONNET PE NE. W When thermostat sends a signal to W, a 4-vac signal is applied across sequencer/relay number, causing it to close. When sequencer/relay number closes, first stage of electric heat is energized. In straight electric heat, fan is also energized through the normally-closed contacts of fan relay. In cooling, heat pump, or manual fan mode, fan will already be running since fan relay would have been energized. When thermostat stops calling for electric heat, the 4-vac signal to sequencer/relay number turns off and sequencer opens after a delay of 60 to 90 sec. Heaters equipped with relays will be de-energized immediately. When sequencer/relay opens, first stage of heat turns off along with fan, providing thermostat is not calling for the fan.. W3 When a signal is sent to W3, a 4-vac signal to sequencer/relay number causes it to close, with second stage of electric heat turning on. The 4-vac signal applied to sequencer/relay number causes fan to operate. Timing is such that sequencer/relay number will turn on before sequencer/relay number. When signal to W3 is turned off, sequencer/relay number opens. If W is also satisfied, first stage of electric heat and fan will also turn off, providing thermostat is not calling for the fan. AUTION: NOT SUITABLE FO USE ON SYSTEMS EXEEDIN 50V TO OUND ATTENTION: NE ONVIENT PAS AUX INSTALLATIONS DE PLUS DE 50 V A LA TEE Fig. 3B FFD Typical Wiring Diagram OMPONENT AANEMENT SYSTEM TANSFOME: 40.0VA ND FAN OIL/HEATE: 8.4VA EMAININ VA AVAILABLE: 3.6VA SEE NOTE #6 OM ELAY LS HT 8 4 V 08 V 6 8 6 4 30 V ELAY 0 LS HT E 4 T F ELAY VD OIL L L N DIS PB NO E 60A 60A F ND SPT ON SPT -LOW N Y FM NO F -HI ND F AP PB T ON N/-ND -OM Y SEE NOTE #5 FAN MOTO THEMALLY POTETED AP OM 08V 30V LEEND OM W AP APAITO OM OMMON HI FM TAN BAIE SEE NOTE #7 DIS DISONNET F FUSE LO N/ INDOO OUTDOO FM FAN MOTO ND THEMOSTAT UNIT FIELD POWE WIIN NOTES: F PB FAN ELAY ND. Use copper wire (75 c min) only between disconnect switch and unit. EQUIPMENT OUND. To be wired in accordance with nec and local codes. HT HEATE 3. If any of the original wire, as supplied, must be replaced, use the same or LS LIMIT SWITH equivalent type wire. MAKED TEMINAL 4. eplace low voltage fuse with no greater than 5 AMP fuse. PLU AND EEPTALE 5. () Speed Motor uses HI () and LOW (). PB PINTED IUIT BOAD 6. Smaller heaters will have fewer components. E ETIFIE 7. onnect to, to, etc., see outdoor instructions for details. SPT FAN SPEED TAP LOATION 8. ooling controls wiring not used with electric heaters. TAN TANSFOME UNMAKED TEMINAL This compartment must be closed except MINIMUM MOTO SPEED SELETION when servicing. FAN OIL SIZE 08 04 030 MOTO SPEED ONE HT LO LO LO OTATION 34494-0 EV. A MOTO SPEED TWO HT LO LO LO DIS DIS DIS 5 DIS SEE NOTE #8 HT LS LS TAN HT A989 3. E When thermostat sends a signal to E, a 4-vac signal is sent to sequencer/relay number 3. The 4-vac signal applied to sequencer/relay number 3 turns on third stage of electric heat. The 4-vac signal applied to sequencer/relay number turns on first stage of electric heat and fan. When thermostat stops calling for electric heat, the signal to sequencers/relays,, and 3 are turned off, and sequencers/relays open. This causes electric heat to turn off with fan providing thermostat is not calling for the fan. NOTE: Electric heaters are factory wired with all stages tied together. If independent staging is desired, consult outdoor thermostat installation instructions, or corporate thermostat instructions. III. TOUBLESHOOTIN THE PINTED-IUIT BOAD Use wiring schematics shown in Fig. 4 and 5 as a guide in troubleshooting PB unless otherwise noted. A. If Fan Will Not Turn On from Thermostat: IF THEE IS NO HIH VOLTAE TO TANSFOME:. heck plug/receptacle connection. This supplies power from heaters to PB Fan elay. Be sure plug is connected properly.
3753 T-O-D 60TX HH9ZA945 975 L45-55F 3753 T-O-D 60TX HH9ZA945 975 L45-55F WANIN ELETI SHOK HAZAD DISONNET EMOTE POWE SUPPLY BEFOE OPENIN PANEL. SPT NO N 5 PULL TO OPEN FAN ELAY 386-0 EV. A FFD ONTOL BOX 3753 T-O-D 60TX HH9ZA945 970 L45-55F 3753 T-O-D 60TX HH9ZA945 970 L45-55F WANIN ELETI SHOK HAZAD DISONNET EMOTE POWE SUPPLY BEFOE OPENIN PANEL. PULL TO OPEN 386-0 EV. A FFA/FFB/FF ONTOL BOX Fig. 3 Electric Heater ontrol Boxes A9884. heck sequencer/relay number and plug wiring. Yellow wire should be connected to pin number 9 of plug and to limit switch. Black wire should be connected to pin number 7 of plug and to sequencer/relay number. 3. heck field power leads L and L. If these are not receiving power, system cannot function. IF TANSFOME HAS HIH VOLTAE APPLIED TO IT:. heck low-voltage transformer leads (red) and (brown). Be sure they are wired to correct locations.. heck output voltage of transformer secondary side (red) and (brown). Be sure transformer output is between 8 and 30 vac. If transformer output is incorrect and transformer is receiving correct input voltage (08v or 30v), then transformer needs to be replaced with recommended transformer. If no problem exists with transformer secondary, proceed to items 3 and 4. 3. heck low-voltage fuse shown in Fig. 3A. If fuse is blown, replace it with an identical 5-amp fuse. The transformer cannot supply power to board with fuse blown or loose. If fuse blows when unit has power applied to it, the system most likely has of the following problems: a. heck all 4-v wiring for an electrical short. b. The maximum load on transformer is 40 VA. If load on transformer is excessive, the low-voltage 5-amp fuse will blow to protect transformer. If load exceeds VA rating of transformer, a larger VA rated transformer needs to be installed. heck sequencers/relays for excessive current draw. c. heck wiring of heaters. If a heater is miswired, fuse may blow. If a heater is miswired, correct miswiring by comparing it to heater wiring label. 4. heck connections on primary side of transformer. If they are not connected properly, the transformer secondary cannot supply the 4-v signal to energize fan relay. If transformer is receiving correct primary voltage but is not putting out correct secondary voltage, transformer needs to be replaced. B. If Electric Heat Stages Will Not Turn On But Fan Will Turn On: IF THEE IS NO HIH VOLTAE TO TANSFOME:. heck plug connection between heaters and board. This supplies power to transformer and fan. Be sure plug is connected properly.. heck sequencer/relay number and plug wiring. Yellow wire should be connected to pin number 9 of plug and to limit switch. Black wire should be connected to pin number 7 of plug and to sequencer/relay number. 3. heck incoming high-voltage power leads. If these are not receiving power, system cannot function. IF TANSFOME HAS HIH VOLTAE APPLIED TO IT:. heck low-voltage transformer leads (red) and (brown). Make sure they are wired to correct location. The unit will not function without proper connections.. heck output voltage of transformer secondary side (red) and (brown). If transformer output is low (less than 8 vac), refer to items 3 and 4 of previous "If Transformer Has High Voltage Applied To It" section. IF TAES AE OVEHEATED ON BAK OF PB: Usually whenever a trace is blown on PB, it means either there has been a high-voltage short or high voltage has been applied to low-voltage circuit. This can be prevented by making sure PB is wired correctly before PB has power applied to it.. If Transformer Fuse Keeps Blowing: When low-voltage fuse blows, it means transformer would have blown if fuse had not been in circuit to protect it. The fuse usually blows when there is a high current draw on transformer, high 6
THIS OMPATMENT MUST BE LOSED EXEPT FO SEVIIN BLOWE MOTO OTATION AUTION: NOT SUITABLE FO USE ON SYSTEMS EXEEDIN 50V TO OUND ATTENTION: AP -OM 30KW PH SHEMATI DIAAM FIELD POWE WIIN DISONNET PE NE HVTB ND SEE ATIN PLATE FO VOLTS & HETZ SEE NOTE # L LS6 HT6 FU5 FU6 HT5 SEQ 3 LS5 0 9 LS4 HT4 8 7 B/FU3 B/FU4 LS3 HT3 SEQ 6 5 LS HT 4 3 B/FU LS HT SEQ B/FU SEQ SEQ3 SEQ ON AY PLU 9 7 3 6 9 7 3 6 4 4 FM SPT -LO -MED -HI N/-ND OM PB N NO F 08V 30V TAN Y NOTES:. USE OPPE WIE (75 MIN) ONLY BETWEEN DISONNET SWITH AND UNIT.. TO BE WI IN AODANE WITH NE AND LOAL ODES. 3. TANSFOME PIMAY LEADS, E 08V, 30V. 4. IF ANY OF THE OIINAL WIE, AS SUPPLIED, MUST BE EPLAED, USE THE SAME O EQUIVALENT TYPE WIE. 5. EPLAE LOW VOLTAE FUSE WITH NO EATE THAN 5 AMP FUSE. 6. 0KW HEATE USES ONE DOUBLE POLE LS ON MIDDLE TOP ELEMENT. 7. 8, 4 AND 30KW HEATES USE DOUBLE POLE LIMIT SWITHES. 8. LAEST HEATES AE SHOWN, SMALLE HEATES WILL HAVE FEWE ELEMENTS AND OMPONENTS. 9. PHASE HEATES AE SHOWN WI FO SINLE SUPPLY IUIT. 0. USE 60 AMP LASS K FUSES ONLY, FO EPLAEMENT.. (3) SPEED MOTO SHOWN. OPTIONAL () SPEED MOTO USES HI () AND LOW ( O ).. ONNET TO, TO, ET., SEE OUTDOO INSTUTION FO DETAILS. 3. IF WIE IMP IS EMOVED AN EMEENY HEAT ELAY IS EQUI. (SEE OUTDOO-THEMOSTAT INSTUTIONS) 34-0 EV. F T WHT W W3 L Y W WHT SEE NOTE #3 BAIE SEE NOTE # INDOO THEMOSTAT E OUTDOO UNIT EP AP OM F FM F FU ND HVTB HT L LEEND APAITO OMMON LOW VOLTAE FUSE FAN MOTO FIELD POWE WIIN PB FAN ELAY LINE FUSE EQUIPMENT OUND HIH VOLTAE TEM BLOK HEATE FIELD POWE WIIN L LS PB SEQ TAN EP B FIELD POWE WIIN LIMIT SWITH MAKED TEMINAL PLU AND EEPTALE PINTED IUIT BOAD SEQUENE TANSFOME UNMAKED TEMINAL EEPTALE IUIT BEAKE PLU 9 7 3 6 4 08/40VA 4VA 4VA 9 7 3 6 4 ESP L Y E L OOLIN ONTOL ONLY FIELD POWE WIIN DISONNET PE NE HVTB SEE ATIN PLATE FO VOLTS & HETZ 30KW 3PH SHEMATI DIAAM ND L3 SEE NOTE # LS6 HT6 FU5 FU6 SEQ 3 LS5 HT5 0 9 LS4 HT4 8 7 B/FU3 B/FU4 LS3 HT3 SEQ 6 5 LS HT 4 3 B/FU B/FU LS HT SEQ SEQ ON SEQ SEQ3 AY 9 7 3 6 4 08/40VA 4VA 4VA L PLU Fig. 4 Wiring Diagram of Sequencer Heater A94346 voltage applied to low-voltage circuit, or a direct secondary short. When there is a high current draw on transformer, it is most likely because transformer has been shorted or system is trying to draw more VA than transformer rating allows. When fuse blows because of high voltage, the system has mixed high- and low-voltage signals.. heck wiring of sequencers/relays as shown in Fig. 4 and 5. Be sure transformer is not shorting out because thermostat wires are miswired.. heck wiring of sequencers/relays as shown in Fig. 4 and 5. Be sure low-voltage and high-voltage wiring is correct. 3. heck VA draw on transformer. If VA draw is more than VA rating of transformer, fuse will blow. If this is the case, replace transformer with one that has a higher VA rating and meets system specifications. D. If Fan uns ontinuously:. If PB has no low-voltage power, check blue and black fan leads. These may be switched at sequencer/relay.. If PB has low-voltage power, check fan relay to see if it is opening and closing. It may be stuck in the normally-closed position due to debris in relay. 7
THIS OMPATMENT MUST BE LOSED EXEPT FO SEVIIN L FU PLU EP OM HI MED LO NOTES: SHEMATI DIAAM FIELD POWE WIIN SEE ATIN PLATE FO VOLTS & HETZ SEE NOTE # 9 9 L3 FU3 AP L B SPT BLOWE MOTO OTATION FM L3 B ON 7 3 7 3 N NO F PB DISONNET PE NE ND L4 L L4 L INTENAL POTETION MAY B B BE EITHE FUSES O IUIT BEAKES LS4 HT4 ELAY 3 4 LS3 HT3 ELAY 8 6 LS HT ELAY 4 LS HT ELAY 4 ELAY VD OIL T D ELAY ELAY 3 VD OIL VD OIL OM N ND 08V TAN BAIE 6 6. Use copper wire (75 min.) only between disconnect switch and unit.. To be wired in accordance with N.E.. and local codes. 3. If any of the original wire, as supplied, must be replaced, use the same or equivalent type wire. 4. eplace low voltage fuse with no greater than 5 amp fuse. 5. Use 60 amp class K fuses only, for replacement. 6. (3) speed motor shown. Optional () speed motor uses HI () and LOW ( or ). 7. onnect to, to, etc., see outdoor instruction for details. 8. Smaller heaters will have fewer components. 34984-0 EV. A F T 30V Y WHT E W WHT INDOO THEMOSTAT FU4 FU E Y W Y SEE NOTE #8 OUTDOO UNIT 4 4 SEE NOTE #6 AUTION: NOT SUITABLE FO USE ON SYSTEMS EXEEDIN 50V TO OUND ATTENTION: NE ONVIENT PAS AUX INSTALLATIONS DE PLUS DE 50 V A LA TEE B AP OM F FM F FU ND SPT ELAY 6 8 4 0 E ELAY 6 8 4 0 TD ELAY 3 6 8 4 0 TD OMPONENT AANEMENT HT HT3 HT LS SYSTEM TANSFOME: 40.0VA FAN OIL/HEATE:.8VA EMAININ VA AVAILABLE: 8.VA OM 4 V L4 L L L3 ND ND FU4 FU FU FU3 LS 3 & 4 HT4 T F N PB NO F SPT IUIT BEAKE APAITO OMMON LOW VOLTAE FUSE FAN MOTO FIELD POWE WIIN PB FAN ELAY LINE FUSE EQUIPMENT OUND FAN SPEED TAP LOATION -LOW -MED -HI N/-ND TAN LEEND FM LS 08 V 30 V L4 L3 L L B B 60A 60A 60A 60A AP -OM FAN MOTO THEMALLY POTETED HT LS PB E TAN TD HEATE LIMIT SWITH MAKED TEMINAL PLU AND EEPTALE PINTED IUIT BOAD ETIFIE TANSFOME UNMAKED TEMINAL TIME DELAY ETIFIE MINIMUM MOTO SPEED SELETION FAN OIL SIZE 08 04 030 036 04 048 060 070 MOTO SPEED AT 0 KW -- -- MED LO LO LO LO LO 3 Fig. 5 Wiring Diagram of elay Heater A99E E. Transformer Failure:. heck 08-v and 30-v transformer connections. They may be miswired. IUIT BOAD FUNTION AND TOUBLESHOOTIN HK6A00 and HK6A003 ircuit Boards This section of the service manual describes the HK6A00 and HK6A003 printed-circuit boards (PB) by examining the functional operation of the printed-circuit board s components. I. PB OMPONENT LAYOUT AND DESIPTION Layout of the actual printed-circuit boards are depicted in Fig. 6 and Fig. 7.. The low-voltage terminal board is used to connect the indoor thermostat to the low, 4-v side of the transformer, and to serve as a junction between the indoor thermostat and the outdoor section.. Break off the tabs. a. W-3 Used to control (stage) the second stage of electric heat. The first stage controlling electric heat and the indoor fan are interlocked through diodes. b. W-E Used to control (stage) the third stage of electric heat. 3. A fuse is used to protect the low-voltage transformer. 4. AUX and AUX are connections for the latent capacity control, delay off kit, -speed kit and air conditioning accessories. 5. F, F, F3, and F4 are connections for the indoor fan. 6. EA and EA are 40-v connections, which parallel fan lead connections, for the electronic air cleaner. 7. L and L are 40-v connections which parallel power input. 8
HK6A00 LOW VOLTAE TEMINAL BOAD ND STAE W-3 W-E 3D STAE ELETI HEAT BEAKOFF TABS FO STAIN F- FAN TDB NOT USED INTELOK DIODES HK6A00A FUSE (LOW VOLTAE) 5 AMP FUSE MAX PLU 3 6 9 5 8 4 7 AUX 4VD AUX ONNETIONS FO VAIOUS AESSOIES TANSFOME ONNETIONS 0 TANSFOME A LINE FAN ELAY DUMMY F4 F3 FAN ONNETIONS T OMMON T DUMMY T3 L L EA EA DUMMY FAN OMMON F F 40 VA 40 VA ELETONI AI LEANE ONNETIONS Fig. 6 HK6A00 Printed-ircuit Board A9705 8. T, T and T3 are connections for the primary, high-voltage side of the transformer. 9. The fan relay is controlled by the thermostat and turns the fan on and off. 0. A plug is used as the connection for the PB power and electric heaters. Note the pin numbers on the plug.. Diodes provide D power for the fan relay and the first stage of electric heat: W, W3 or E. II. PB OMPONENT FUNTIONS A. Low-Voltage Terminal Board The low-voltage terminal board connects the indoor thermostat to the outdoor unit as shown in Fig. 8. The terminals are listed as follows along with their functional control.. is used to connect the secondary side of the transformer. The red wire provides low voltage (4v) to the PB and the thermostat. is fused on the HK6A003 board. 9
HK6A003 LOW VOLTAE TEMINAL BOAD Y FD- W3 ND STAE L W W-3 ELETI HEAT BEAKOFF TABS FO STAIN FAN INTELOK DIODES AND FAN TIME DELAY OFF IUIT O E W-E 3D STAE Y FUSE (LOW VOLTAE) PLU 5 AMP FUSE MAX 0 9 8 7 6 5 4 3 HK6A003 AUX 4VD AUX ONNETIONS FO VAIOUS AESSOIES FAN ELAY F4 TANSFOME ONNETIONS T OMMON T DUMMY TANSFOME A LINE T3 L EA L EA 40 VA 40 VA DUMMY DUMMY FAN OMMON F3 F F FAN ONNETIONS ELETONI AI LEANE ONNETIONS Fig. 7 HK6A003 Printed-ircuit Board A9706. is used to connect the brown wire of the thermostat to provide a return path to ground through the fuse which protects the transformer. is fused on the HK6A00 board. 3. is used to control the switching of the relay to turn the fan on through the normally open contact of the relay. 4. Y on the HK6A00 is used as the junction for the outdoor section s Y connection which controls the compressor contactor for heat pump and cooling modes. The HK6A003 board contains a 90-sec fan-off delay which begins timing when the Y is de-energized. 5. O is used as a junction for a heat pump reversing valve circuit. 0
6. W is used to turn on the first stage of electric heat which is interlocked with the fan through the normally closed fan relay. Unless the tabs are broken off, all stages of electric heat will turn on when W receives a signal from the thermostat. 7. W3 is used to turn on the second stage of electric heat. Note the W and W3 tab must be broken off for individual staging to take place. Energizing W3 will always turn on the first stage through the diodes even if the tabs are broken off. 8. E is used to turn on the third stage of electric heat. Note that the W3 and E tab must be broken for this individual staging. Energizing E will always turn on the first stage through the diodes even if the tab is broken off. 9. L is used as a junction to wire a diagnostic light (LED) on selected thermostats. B. Transformer The proper wiring of the transformer on the HK6A00 board is illustrated in Fig. 8. Note that T, T, and T3 are wired to the primary or high side of the transformer. The blue wire is connected to T3 for 08-v applications. The red wire is connected to T3 for 30-v applications. Units are factory wired at 30v. The T terminal is a dummy.. Indoor Fan. Wiring--The fan connects to F, F, F3, and F4 as shown in Fig. 8. Note that F and F3 are dummy terminals. The desired fan speed is connected to F4 and the common is connected to F. Units are factory wired at medium speed.. Functional ontrol a. Thermostat and elay ontrol--when the thermostat calls for the fan in cooling, heat pump, electric heat, or fan-only mode, a 4-v dc signal is sent to the relay. This causes the relay to close its normally open contacts, thus turning on the fan. When the thermostat no longer calls for the fan, the signal sent to the relay is turned off and the relay opens causing the fan to turn off. The HK6A003 board contains a 90-sec fan-off delay when Y is de-energized. b. Sequencer Interlock--The fan will also turn on whenever there is any call for electric heat, even if the fan relay is not energized. This happens because the fan is interlocked with the first stage of electric heat through the normally closed contact of the fan relay. D. Electric Heat When the thermostat calls for electric heat, a 4-v signal is sent to the PB through W, causing the first stage to turn on. W3 and E also receive the signal if the tabs are not broken off the PB. The signal sent to W causes the first stage to turn on. If the tabs are broken off the PB, the sequencers can be controlled individually to stage the electric heat. The sequence control is described in the following section:. W--When the thermostat sends a signal to W, a 4-v dc signal is applied across sequencer number, causing it to close. When sequencer number closes, the first stage of electric heat energizes after a short delay. In straight electric heat, the fan is also energized through the normally closed contacts of the fan relay. In cooling, heat pump, or manual fan mode, the fan will already be running since the fan relay would have been energized. When the thermostat stops calling for electric heat, the 4-v dc signal to sequencer number turns off and the sequencer opens after a delay of 60 to 90 sec. When the sequencer opens, the first stage of heat turns off along with the fan, providing that the thermostat is not calling for the fan. Note that the electric heat cannot be turned on without the fan being turned on at the same time. This is a fan interlock system.. W3--When a signal is sent to W3, control signals are sent out to the sequencers; a 4-v dc signal to sequencer number through the diode interlock, and a 4-v ac signal to sequencer number. The 4-v ac signal applied to sequence number causes the sequencer to close, with the second stage of electric heat turning on after a short delay. The 4-v dc signal applied to sequencer number causes the first stage of electric heat to turn on in the same manner as described in W above. Note that W3 is interlocked with the fan, since sequencer number is turned on whenever W3 has a signal sent to it. Timing is such that sequencer number will turn on before sequencer number. When the signal to W3 is turned off, sequencer number opens after a short delay. If W is also satisfied, the first stage of electric heat and the fan will also turn off, providing the thermostat is not calling for the fan to be on. E--When the thermostat sends a signal to E signals are sent out to the sequencers. A 4-v ac signal is sent to sequencer number 3 and a 4-v dc signal is sent to sequencer number. The 4-v ac signal applied to sequencer number 3 turns on the third stage of electric heat. The 4-v dc signal applied to sequencer turns on the first stage of electric heat and the fan in the same manner as W3. Note that E is also interlocked with the fan. When the thermostat stops calling for electric heat, the signals to sequencers and 3 are turned off and the sequencers open. This causes the electric heat to turn off with the fan if the thermostat is not calling for the fan. E. Accessories. EA and EA for Electronic Air leaners a. There are 40-v electronic air cleaner contacts provided at EA and EA. The electronic air cleaner is connected in parallel with the fan so that it is on whenever the fan is on. A 0-v installation is similar in function but connected between EA and neutral of 30-v: 0-v transformer connected to EA and EA. efer to electronic air cleaner literature for further information.. AUX and AUX for -Speed Fan elay Kit a. Use to control fan speed operation, high speed for cooling, heat pump, and fan-only modes. Low speed is used for electric heat. Fig. 9 shows proper connection for 4-v dc -speed fan relay kit. Note that kit s relay coil is in parallel with fan relay coil on PB connected to AUX and AUX. Make sure the normally closed contact is connected to the lower speed. b. The latent capacity control kit is used to control fan speed operation when the relative humidity is above a set point on humidistat. Humidistat opens and -speed fan relay remains in normally closed position with fan motor running at a lower speed for maximum humidity control. Fig. 0 shows proper connection for latent capacity control kit. Note that it is connected in the same manner as -speed fan relay kit but with relay connected to humidistat (orange wires). c. Time delay-off relay kit is used to increase the efficiency of the system by delaying the fan from turning off after the thermostat is satisfied on the HK6A00 board. The HK6A003 board has this feature as standard. The proper wiring and mounting of the time delay-off relay kit is shown in Fig.. d. Latent capacity control and time delay-off connections are shown in Fig., for the HK6A00 board only. III. TOUBLESHOOTIN THE PINTED-IUIT BOAD Use Fig. 3 wiring schematic as a guide in troubleshooting the PB unless otherwise noted.
FU5 LS 6 HT6 FU6 SEQ 3 LS 5 HT5 0 9 FU3 LS 4 HT4 8 7 FU4 SEQ LS 5 HT5 6 5 FU LS HT 4 3 SEQ LS HT FU LOW VOLTAE TEMINAL BOAD W3 L W-3 W O E W-E TO INDOO THEMOSTAT AY F- HK6A00A Y FAN TDB 5 AMP FUSE MAX ONNET E TO E TO ET. SEQ AY O SEQ3 SEQ 3 6 9 5 8 4 7 AUX 4VD AUX 0 TANSFOME A LINE ELAY DUMMY F4 F3 -MED -HI T OMMON T DUMMY T3 L EA L EA 40 VA 40 VA DUMMY FAN OMMON F F -LO AP FM -OM -LO -MED -HI OMM (08V) (30V) N/-ND TAN (4V) (4V) Fig. 8 0kw to 0kw ircuits A9707
F OM NO N LOW MT SPD HI MT SPD O AUX AUX 4 VD FAN OMMON UNUSED LEAD F4 F3 F 08/40 VA L F L O Y W3 W E LOW VOLTAE BOAD B F B MAKED TEMINAL UNMAKED TEMINAL FIELD TL WIIN FATOY POWE WIIN FIELD POWE WIIN FAN ELAY IUIT BOAD TWO SPEED FAN ELAY WIIN -05868-A T T TANSFOME A LINE OMMON DUMMY OMMON L AUX VA F4 F3 F EA FAN F EA T3 L Fig. 9 Two-Speed Fan elay Kit A9708 AUX O NO TO HIHE FAN SPEED AUX AUX L O Y W E SD- W3 LOW-VOLTAE OIL TEMINALS N TO LOWE FAN SPEED DUMMY TEMINALS FO UNUSED FAN MOTO SPEED-TAP LEADS FAN MOTO OMMON LEAD 3
O LOW MT SPD HI MT SPD FAN OMMON UNUSED LEAD AUX NO F O N NO OM AUX AUX 4 VD F4 F3 F F 08/40 VA L HST L O Y W3 W E LOW VOLTAE BOAD B AUX VA MAKED TEMINAL UNMAKED TEMINAL FIELD TL WIIN FATOY POWE WIIN FIELD POWE WIIN F FAN ELAY B IUIT BOAD HST HUMIDISTAT LATENT APAITY ONTOL WIIN -05868-A T T TANSFOME A LINE OMMON DUMMY OMMON L F4 F3 F EA FAN F EA T3 L Fig. 0 Latent apacity ontrol Kit A9709 AUX OANE WIES TO HUMIDISTAT NO TO HIHE FAN SPEED N TO LOWE FAN SPEED AUX FAN MOTO OMMON LEAD L O Y W3 W E SD- 4
OM 3 NO N L W3 W E LOW VOLTAE BOAD MAKED TEMINAL UNMAKED TEMINAL FIELD TL WIIN FATOY POWE WIIN FIELD POWE WIIN F FAN ELAY B IUIT BOAD TD TIME DELAY ELAY TD O Y Fig. Time Delay-Off elay Kit FAN OMMON UNUSED LEAD UNUSED LEAD AUX AUX 4 VD F4 F3 F 08/40 VA L F B TIME DELAY ELAY WIIN -05868-3A A97030 OMMON L F EA FAN F EA AUX F4 F3 T3 L T T TANSFOME A LINE OMMON DUMMY TO FAN MT SPEED TAP AUX L O Y W E F- HK6A00 W3 FAN MOTO SPEED-TAP LEAD FAN MOTO OMMON LEAD 5
TO HUMIDISTAT (OPTIONAL, SHOWN WITH DASHED LINES) NO TO HIHE FAN SPEED O LOW-VOLTAE OIL TEMINALS O O F B F O OM L NO N W3 W E 3 LOW VOLTAE BOAD MAKED TEMINAL UNMAKED TEMINAL FIELD TL WIIN FATOY POWE WIIN FIELD POWE WIIN FAN ELAY IUIT BOAD HST HUMIDSTAT TD TIME DELAY ELAY LOW MT SPD HI MT SPD OM NO N TD O Y AUX AUX 4 VD FAN OMMON UNUSED LEAD F4 B F3 F 08/40 VA L F TIME DELAY ELAY TWO SPEED FAN ELAY (LATENT APAITY) -05868-4A Fig. Latent apacity ontrol and Time Delay-Off elay Kits A9703 W3 L O Y W E T T TANSFOME A LINE OMMON DUMMY OMMON L VA F4 F3 F EA FAN F EA N TO LOWE FAN SPEED AUX O AUX FAN MOTO OMMON LEAD NO HST SD- T3 L 6
FU FU3 LS 4 HT4 8 7 FU4 FU SEQ LS 3 HT3 6 5 LS HT 4 3 SEQ LS HT TEM BOAD W3 SEQ SEQ O 3 6 5 4 9 8 7 0 PLU ELAY 5 AMP FUSE MAX W E L O Y 40 VD AUX AUX F4 L O W Y E INDOO THEMOSTAT DUMMY F3 T OMMON A LINE T DUMMY T3 DUMMY F L EA FAN L EA 40 VA 40 VA OMMON F -OMMON OMM (4V) (08V) TAN (30V) OMM AP FM -LO -MED -HI N/-ND ON TEMINAL BOAD ABOVE Fig. 3 Wiring Schematic A9703 7
A. If the fan will not turn on from the thermostat: IF THEE IS NO HIH VOLTAE TO THE PB:. heck the plug/receptacle connection; this brings power to the PB. Make sure the plug is connected properly.. heck sequencer number and the plug s wiring; the yellow wire should be connected to pin number 9 of the plug and the limit switch. A black wire should be connected to pin number 7 of the plug and to sequencer number. 3. heck power leads L and L. If these are not receiving power, the system cannot function. IF THE PB HAS HIH VOLTAE APPLIED TO IT:. heck the low-voltage transformer leads, and. Make sure they are wired to the correct locations. Note that Fig. 3 shows wiring of the HK6A00 board.. heck the output voltage of the secondary side, and, of the transformer. If the circuit board is a HK6A003, make sure the ground strap is in place from to the bracket. This strap must be in place to complete the 4-v circuit. Make sure the transformer output is around 4-v ac. If the transformer output is zero-v ac and the transformer is receiving the correct input voltage (08-v or 40-v), then the transformer needs to be replaced with the recommended transformer. If the transformer output is 4-v ac, then proceed to 3 and 4. 3. heck the low-voltage fuse shown in Fig. 6 and Fig. 7. If the fuse is blown, replace it. The transformer cannot supply power to the board with the fuse blown or loose. If the fuse blows when the unit has power applied to it, the system most likely has of the following problems: a. If the transformer is shorting out, check the wiring of the transformer. b. The maximum load on the transformer is 40 VA. If the load on the transformer is excessive, the low-voltage, 5-amp fuse will blow to protect the transformer. If the load exceeds the VA rating of the transformer, a larger VA rated transformer needs to be installed. heck the sequencers for excessive current draw. c. heck the wiring of the heaters. If the heater is miswired, the fuse may blow. heck the diodes shown in Fig. 4 for signs of overheating. If the heater is miswired, correct the miswiring. 4. heck the T, T, and T3 connections on the primary side of the transformer. If they are not connected properly, the low-voltage terminal board cannot supply the 4-v signal to energize the fan relay. If the transformer is receiving the correct primary voltage but is not outputting the correct secondary voltage, the transformer needs to be replaced. B. If the electric heat stages will not turn on but the fan will turn on:. heck the wiring of the sequencer. Pay particular attention to the high and low-voltage wiring of the sequencers.. heck the plug wiring to make sure that it is wired correctly. 3. heck the voltage to the sequencer; sequencer number receives a 4-vac signal. If it is receiving the correct voltage, check to see if the sequencer is closing. If the sequencer is not closing but is receiving the correct voltage, replace the sequencer. If the sequencer is closing, check the high-voltage wiring as discussed in and.. If the electric heat and the fan will not turn on: IF THEE IS NO HIH VOLTAE TO THE PB:. heck the plug connection. This brings power to the PB transformer and the fan. Make sure the plug is connected properly.. heck sequencer number and the plug wiring. The yellow wire should be connected to pin number 9 of the plug and the limit switch. The black wire should be connected to pin number 7 of the plug and to sequencer number. 3. heck incoming high-voltage power leads. If these are not receiving power, the system cannot function. IF THE PB HAS HIH-VOLTAE APPLIED TO IT:. heck the low-voltage transformer leads, and. Make sure they are wired to the correct location. The unit will not function without proper connections.. heck the output voltage of the secondary side, and, of the transformer. If the circuit board is an HK6A003, make sure the ground strap is in place from to the bracket. This strap must be in place to complete the 4-v circuit. If the transformer output is zero-v ac, refer to "If the PB has high voltage applied to it" in column, numbers 3 and 4. D. If the traces are burnt off the back of the PB: Usually whenever there is a trace blown on the PB it means either there has been a high-voltage short or high voltage has been applied to the low-voltage circuit. This can be prevented by making sure the PB is wired correctly before the PB has power applied to it. E. If there are blown diodes:. If diodes a and b are blown, it is probable the electric heater plug was miswired. orrect the miswiring. It should be noted the board will need to be replaced if the diode indicated is bad.. If any of the c diodes are blown, the fan is miswired to of the low-voltage terminals, AUX or AUX. heck to make sure that the fan leads are connected to the proper terminals as shown in Fig. 3. If the fan is connected properly, make sure that no other high voltage is applied to the AUX terminals. F. The PB fuse keeps blowing: When the low-voltage fuse blows, it means the transformer would have just blown if the fuse had not been in the circuit to protect it. The fuse usually blows when there is a high current draw on the transformer, high voltage applied to the low-voltage circuit, or a direct secondary short. When there is a high current draw on the transformer, it is most likely because the transformer has been shorted or the system is trying to draw more VA than the transformer is rated for. When the fuse blows because of high voltage, the system has mixed high- and low-voltage signals.. heck the transformer and thermostat wiring as shown in Fig.. Make sure the transformer is not shorting out by the thermostat wires being miswired.. heck the wiring of the sequencers as shown in Fig. 3. Make sure the low-voltage and the high-voltage wiring are connected to the proper sequencers. 3. heck the VA draw on the transformer. If the VA draw is more than the VA rating of the transformer, the fuse will blow. If this is the case, replace the transformer with that has a higher VA rating and meets system specifications.. The fan runs continuously:. If the PB has no low-voltage power, check the blue and black fan leads. These may be switched at the sequencer.. If the PB has low-voltage power, check the fan relay to see if it is opening and closing. It may be stuck in the normally closed position due to debris in the relay. 3. See Service Manager Bulletin (SMB) 9-3. H. Transformer failure:. heck the 08-v and 40-v taps connected to T, and T3. They may be miswired. 8
W-E W-3 BLOWN DIODE (b) F- FAN TDB BLOWN DIODE (a) HK6A00A 5 AMP FUSE MAX BLOWN DIODE (c) 3 6 9 5 8 4 7 0 TANSFOME A LINE ELAY DUMMY AUX 4VD AUX F4 F3 T OMMON T DUMMY T3 L L EA EA DUMMY FAN OMMON F F 40 VA 40 VA Fig. 4 ontrol Board Noting Diodes A97033 ELETI HEATE FUNTION AND TOUBLESHOOTIN This section describes KFA, KFB, KF, and KFD series electric heaters in exclusion of Smart Heat by examining the functional operation of these heaters. I. DESIPTION OF ELETI HEATE OMPONENTS A. Limit Switch The limit switch is a temperature-sensitive control whose function is to prevent system from overheating in abnormal conditions. The temperature settings often vary from heater to heater due to variations in airflow patterns and element radiant heat conditions. The devices are sized to remain on-line under heat pump conditions (5 F air off coil) and minimum FM, but trip to prevent outlet air conditions above 00 F or excessive component or duct temperatures. The device itself consists of a bimetallic disc, which when overheated "snaps through" to open a normally-closed highvoltage, high-current switch. When system temperatures cool sufficiently, the switch will automatically reset to its closed position. Normal failure mode for this switch is open. If a limit switch has been determined to be defective, NEVE BYPASS THE LIMIT SWITH. When replacing limit switch, ensure that it is replaced with a limit switch of identical opening temperature and closing differential. Limits switches are typically color coded to identify their range. B. KFA and KFB Sequencer The sequencer is essentially a thermally activated time-delay relay normally activated by low-voltage control signals from thermostat. The typical sequencer is a - or -pole normally-open device which energizes within 0 to 30 sec after application of control signal and de-energizes 60 to 90 sec after control signal is removed. 9
In simplistic terms, the sequencers which we use are nothing more than normally-open limit switches which sit on top of a small resistive heater. When voltage is applied to this heater, a positive temperature coefficient resistor (PT), heat is supplied to a bimetallic disc which "snaps through" and closes switch. The time required for PT to heat to a sufficient point controls ON timing of device. The time required for disc to cool down when power is removed controls OFF time of device. The PT can be varied to provide varied timing. Typically a short ON equates to a long OFF. Because this is a thermally-activated device, ambient conditions affect the ON/OFF cycle. Higher ambient temperature means shorter ON times and longer OFF times. These sequencers may be "ganged up" to 3 on a common mounting plate to control up to 6 heater elements. In this situation, PTs are different in each sequencer to provide a staged ON of a minimum of 0 sec between each sequencer 3 stages of elements since the KFA and KFB series heaters use sequencers in which both switches of the -pole sequencer close simultaneously. Older models used sequencers which had a minimum delay of 0 sec between each switch. Application of these devices is such that the first switch ON not only turns on first heater element, but also ensures that indoor fan is energized, because first ON is last OFF. This ensures fan remains ON until the last heater de-energizes.. KF and KFD Electric Heat elay KF and KFD electric heater packages have relays controlling the heater elements instead of sequencers. A small rectifier PB is mounted to each relay which converts the incoming 4-vac control signal to dc. In addition to the rectifier circuit, the second and third stage relays contain a time-on delay circuit of 5 seconds for second stage, and 8 seconds for third stage. When the control signal is removed from the relays, all relays will open with no time-off delay. II. TOUBLESHOOTIN KFA, KFB, KF, AND KFD SEIES ELETI HEATES A. Discolored Wire Insulation at Terminal heck quick-connect terminal at discoloration. onnection may be loose, creating a high resistance through connection point. B. Fuse Failure. heck for shorted wire. eplace wire. Never try to fix wire using electrical tape.. heck shorted element. If element is shorted, replace heater.. No Heat. heck fuse for failure. If fuse has failed, refer to Fuse Failure section.. heck for faulty transformer. heck output voltage of transformer secondary side (red) and (brown). Make sure output is between 8 and 30 vac. If output voltage is low and input voltage tests normal, replace transformer. 3. heck for miswired heater plug harness. 4. heck limit switch or sequencer failure. These switches should have failed in open position. If output voltage is zero volts, replace switch. 5. heck heater relay and PB (KF and KFD heaters only). ontrol voltage input to PB should be 4-vac. Output to relay should be 8-vdc minimum. If input is present but no output, replace PB. If output is present, replace relay. D. Heater Will Not Turn Off. heck low-voltage wiring for miswire.. heck for shorted elements to ground. 3. eplace sequencer/relays. They may be stuck closed. E. Nuisance Trips. heck for low airflow due to dirty filters, blocked registers, or undersized duct.. heck blower motor and wheel for proper operation. Excessive current draw of motor will cause internal overload to trip. 3. The fan speed may be low. FAN OIL DESIPTION AND TOUBLESHOOTIN FK4B The FK4B is similar to the discontinued FK4A as they both have integrated controls and motor (IM) and their own special circuit board. The greatest difference between the models is the way each goes about delivering air. Setting up desired airflow on the FK4B is obtained by the selections made on Easy Select circuit board. The motor delivers requested airflow as defined by signals received from Easy Select Board and its internal programming. The major difference is that the FK4B motor reacts to changes in system static pressures to maintain constant airflow. Unlike conventional fan coils where static pressure affects airflow, the FK4B is a constant airflow unit. The blower delivers requested airflow up to about 0.7 in. of static pressure. The IM is pre-programmed and contains airflows for all modes of operation. Blower characteristics (airflow, torque, and speed-vs-static pressure) are known from laboratory testing. If any 3 characteristics are known, the fourth is defined. equested airflow is known because of Easy Select board configuration and thermostat signals. Torque is known because it is directly related to armature current which is measured by motor control. Speed is measured from its generated back EMF. This information is entered into an expression which calculates torque from speed and airflow numbers. If calculation does not match stored blower characteristics, torque is adjusted every 0.8 sec until agreement is reached. The unit does not directly measure static pressure, but does react to a change in static to maintain constant airflow. I. INTEATED ONTOLS AND MOTO (IM) The IM is similar to the IM used in FK4A series units, but cannot be used as a replacement without some modification to FK4A unit. onsult SMB 93-005 for motor conversion kit. The electronics of motor are built into rear of motor, deriving the name IM. (See Fig. 5.) An IM is first fed high voltage A power through the 5-pin connector. The A power is then rectified to D by a diode module. After rectification, D signal is electronically communicated and fed in sequential order to 3 stator windings. The frequency of communication pulses determines motor speed. The rotor is permanently magnetized. An IM is powered with high voltage at all times. The motor will not run with high voltage alone. Low voltage must be applied to control plug to run motor. II. PB LAYOUT AND DESIPTION NOTE: Layout of actual PB is depicted in Fig. 6 and 7. The control is a single PB which interfaces a variable-speed IM with other system components. Power for system is supplied from a 30-vac, 60-Hz line. lass voltage (4 vac nom.), used for thermostat connections, is derived from a transformer located in close proximity to control. The primary and secondary of transformer are connected to control board. The 4-vac secondary circuit includes a socket, soldered into circuit at SE, to receive a 5-amp automotive-type fuse. onnection to heater panel is made through -circuit connector P. onnections to thermostat are made at screw terminals. Line voltage for IM is made through 7-circuit connector P. Eighteen quick-connect terminals comprise field select taps for motor. 0