Electrical Problems Fuse(s) blow or circuit breaker trips Does the unit use circuit breakers or fuses? Fuse(s) Circuit breakers Are the fuses dual element time delay? Is the circuit breaker HACR rated? Replace with correct fuse(s) Is it the correct amp rating for the application? Replace with correct circuit breaker Is it the correct amp rating for the application? Is the amp draw excessive at start up? Fan motor Is the fan motor or compressor drawing excessive current? Compressor Check for siezed fan motor or bad run capacitor See compressor diagnostics Fuse blowing due to short. Check fan motor, if OK then see comp diagnostics
Compressor Will t Run Is proper voltage applied at load side of unit disconnect switch? Are the fuses blown or breaker tripped in the disconnect? Check for voltage at contactor coil. Is compressor contactor pulled in? Is compressor overload tripped? Is there power at line side of unit disconnect switch? Replace contactor. Is high or low pressure control open? Allow time for compressor to cool off. Check for tripped breaker in main panel. Determine cause and reset. Check starting components. Replace breaker or Refer to electrician. Check wiring and repair as necessary. Ohm out the compressor windings. Replace the starting components. Check wiring and repair as necessary. Replace compressor.
te: The procedures described below require the skills of a competent, EPA certified refrigeration technician. Also required are a manifold gauge set, digital thermometer with thermocouple type probe, pressure-temperature chart and various hand tools (wrenches, service valve rachet, etc.) Refrigeration Install manifold gauge set onto suction and high side service valves. Record suction line temperature, 4" from compressor. Record discharge line temperature, 4 to 6" from compressor. Record liquid line temperature before filter drier. Compare super heat and sub cooling. Is super heat within factory specs of 10 12 F for freezers or 6 8 F for coolers? Is liquid sub cooling within factory specs of 10 15 F? t a refrigeration system problem. OK Check and verify refrigerant charge. T OK Find and repair leak and recharge system. Is the evaporator ice covered? See refrigerant charging procedure. Charge OK? See Walk-in Cooler or Freezer is Too Cold See TXV diagnostics.
Thermostatic Expansion Valve (TXV) Diagnostics TXV is hunting and will not hold setting. Is the TXV sensing bulb mounted securely to the suction line before the P trap? The TXV is correct for the application? Remount sensing valve properly. Is the valve stuck closed? Replace TXV and drier. Check system for proper operation. Is the valve stuck open? te: To check expansion valves for proper operation, immerse the sensing bulb in a pan of warm water. DO T spray sensing bulb with refrigerant of any kind.
Walk-In Cooler or Freezer Too Warm Are temperature control settings proper for the application? Reset to proper cut out, differential, and check operation Is the relay on the temperature control closed at set point plus differential? Did it work properly? Is there proper line voltage at the solenoid valve coil? Complete Replace control Check through 3 cycles Is the liquid line solenoid valve coil energized? Check Wiring Check coil for open windings Is the solenoid valve open? Are the windings open? Replace solenoid valve body Replace coil See compressor will not run chart on page 3
Walk in cooler or freezer too cold Check temperature control for proper cut out and differential settings Is it set properly? Reset to proper cut out and differential, check through 3 cycles Is the temperature control opening at cut out and closing at cut out plus differential? Did it work properly? Did the relay contacts open? Replace temperature control Replace temperature control Complete Is the liquid line solenoid coil still powered? Check for proper wiring Is the solenoid valve open? See refrigeration system page Replace solenoid valve body
Walk-In Freezer Evaporator Iced Up Ice has formed on the evaporator during the freeze cycle causing blocked air flow Are all evaporator fan motors working? Put system into defrost by manually advancing the timer. Is proper voltage applied to the fan motor(s)? Did the system go into defrost? Check defrost terminator for continuity between black and blue wires. Replace fan motor(s). Check defrost terminator and fan delay switch. Is there continuity between black and red wire? Replace defrost terminator. Check defrost timer motor and contacts; are they good? Replace timer. Check for power at defrost heaters. Ohm out defrost heaters. Check for burnt or loose wiring and repair as required. Do they ohm check OK? Replace defrost heaters. te: If all procedures on this page check good, see TXV diagnostics.
Evaporator Freeze Up at Night or During Low Ambient Conditions Evaporator freezes up at night or during low ambient conditions. Is the suction pressure low? t a refrigeration system problem Is the liquid line cold? Is the liquid line hot? Valve not bypassing in low ambients, replace headmaster valve and drier Possibly low charge, verify and recharge as necessary. Is charge OK? Find and repair leak, replace drier, evacuate and recharge. Check system for proper operation Valve stuck in bypass
Troubleshooting Head Pressure Control Valve (HPCV) te: Head pressure controls work by reference to a preset dome pressure charge on the valve. They do T work based on temperature. If the system is experiencing freeze ups at night or in low ambient conditions, it may be caused by a head pressure control not bypassing properly. Does the system lose cooling or freeze up at night or in low ambient temperatures? Is the suction pressure low? t a refrigeration system problem. Is the liquid line cold? Valve not bypassing in low ambient conditions. Is the liquid line hot? Is the discharge pressure low? Replace headmaster valve and drier. Is the discharge pressure high? Verify refrigerant charge is correct Check system for proper operation. Valve stuck in bypass. In high ambient conditions, low ambient conditions may be simulated by spraying condenser coils with a fine mist of cold water. The headmaster can then be tested as if it were in a cold environment. te: Take care not to spray water directly on fan motor or on exposed electrical connections.
Freezer Drain Pan Icing Up Check drain for blockage. Clear drain as necessary. See note below. Is the drain line trapped outside of the freezer? Repair as necessary. Is the drain pan heater properly positioned and secured to the drain pan? Reposition and secure. Check for proper voltage at drain line heater. OK Check drain line heater for proper resistance. Find and repair cause of improper voltage reading. Replace drain line heater. Warning: Exercise caution when using test instruments around exposed metal surfaces. te: Use only CO2 or Nitrogen to clear plugged drains. DO T use any chemical type of drain cleaners such as Drano, Liquid Plumber, etc.
Walk-In Freezer Door Sweating or Icing Up Check door gasket and sweep for rips, tears, misalignment and proper installation. Replace gasket or sweep and repair as necessary. Check door frame heater for proper amp draw with clamp-on ammeter. Check for door closing properly. Check for proper voltage applied to heater. Check door for proper mounting and bad hinges. Check door frame heater for proper resistance. Find and correct cause of voltage problem. Replace door frame heater. Warning: Exercise caution when using test instruments around exposed metal surfaces.