LTS. Let s Talk Service. Proper Sealed System Diagnosis A Real Timesaver

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1 December 2007 LTS Let s Talk Service NEW SERVICE BULLETINS: Cooking Maytag & Jenn-Air Microwave Combo, trim not flush Jenn-Air & Amana Microwave Ovens, discoloration of cabinets Refrigeration Water reservoir/tube freezing & 22 Bottom mount Refrigerators, compressor Maytag, Jenn-Air & Amana, compressor change INSIDE THIS ISSUE: Proper Sealed System Diagnosis KitchenAid Wall Ovens Two or Three Lights? Microwave Door Torsion Bars NEW RTC Schedule Proper Sealed System Diagnosis A Real Timesaver Often I hear the question How do I know for sure if I have a sealed system problem? This can sometimes be difficult for the inexperienced technician because of all the variables of heat load and temperature. Knowledge of what to expect from a normally operating system is the best start to recognizing a sealed system problem. Sealed system problems are rare and should not be assumed without confirmation. Briefly, the evaporator is where liquid refrigerant is boiling and absorbing heat. This heat comes from inside the refrigerated space. The heatladen vapor is then compressed, causing its temperature to increase to something greater than room temperature. The compressor will pump this high-temp, heat-laden vapor to the condenser, where the heat will readily flow out of it to the cooler room, causing the vapor to change back to a liquid. Remember heat flows from hot to cold. So, what I have to do is see if the evaporator is absorbing heat and to feel if that same heat is being dissipated at the condenser. A normal system with heat load at the evaporator will usually have detectable heat dissipation at the condenser. This is why an experienced technician feels the condenser. It tells him much about what is going on inside at the evaporator. He might do this immediately even before opening the doors and at the same time check to see if the compressor and condenser fan are running. The next thing an experienced tech might do is open the doors and get a temperature reading in each section. Don t make assumptions about the temperatures, confirm them now. Then check the evaporator cover for heavy frost that would indicate a defrost problem. Let s assume, for the sake of discussion, that our evaporator cover is clear and our interior temperatures are noticeably higher than normal. It is now time to check all nonsealed system components before proceeding. Are the compressor, condenser fan, and evaporator fan running? Are the air ducts and damper open? Is the light going off when the door is closed? Are the doors sealing properly? Is the condenser clean? Now back to the sealed system. The last thing I want to do is enter the sealed system before I am sure I have a sealed system issue, so I continue my quest to eliminate it as the problem. If all nonsealed system components are working, I return to the condenser to verify if its overall temperature is higher than room temperature, indicating the system is pumping heat. I can t go by the discharge tube at the compressor, as this is always hot when Sealed System Diagnosis Continued on Page 4

2 Page 2 W h i r l p o o l T e c h l i n e T i p s 2007 KitchenAid Wall Ovens Complaint: The tech sheet shows that there should be a third oven cavity light; the wiring harness connector is present but there is no light fixture. Reason: Our 2007 KitchenAid models were originally designed to have three lights in each cavity. Prior to production start, the third lights was removed from the design. Tech sheets for the models still show the third light being present. A heavier duty transformer is still present and there is an unused connector on the harness for each cavity. This is in the process of changing currently. However, the extra connectors and misleading tech sheets will be present for the near future. Resolution: We need to ensure that the service organization understands that this is normal and not a problem. No corrective measures need to be taken. No parts need to be replaced. Thanks TechLine! The New and Improved SOG, or Service Operating Guide is now available, should you have any questions about warranty service, claims submittal, etc. It s a great tool for rules, regulations, and reference. You can view it at ServiceMatters.com and either print it, or save the Adobe file to your computer for reference. All the changes and additions are in RED, to make them easier to locate. Whirlpool and KitchenAid Built-In and Combo Microwave Doors with Torsion Bars Complaints such as: Door drops down, even after replacing torsion springs Door feels too heavy from day one Not enough torsion in the door Reason: Doors on Whirlpool and KitchenAid Built-in Microwaves and Microwave/Oven Combo s have two torsion bars. The door is designed to come down and stay down. Unlike the lower oven door and unlike dishwasher doors, it is normal for the microwave door to not have much torsion. Resolution: Right Side Use the attachment below to ensure that the torsion springs are properly installed. The door is operating as designed. Left Side Torsion bar LH spring for all Torsion bar RH 30" NON-Stainless model Torsion bar RH 30" Stainless model Microwave door Torsion bars Microwave door Torsion spring, standard duty Microwave door Torsion spring For a video, visit ServiceMatters.com and click TechLine Support Willie O. Parker, Whirlpool TechLine

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5 Page 4 Organization W H I R L P O O L C O R P O R A T I O N Let s Talk Service is a monthly publication of Whirlpool. It is designed and intended to be used by Authorized Whirlpool technicians. This publication may not be reproduced in whole or in part, electronically or otherwise, without the express written permission of the Whirlpool Manager of Publications. Whirlpool Corporation 553 Benson Rd. Mail Drop 8020 Benton Harbor, MI Questions or Suggestions? Judith_A_Wittmann@whirlpool.com Registered Trademark/ Trademark of Whirlpool, U.S.A., Jenn-Air, U.S.A., or Maytag Corporation, or its related entities. All other trademarks are owned by their respective companies. Sealed System Diagnosis Continued from Page 1 the compressor is running. On a normal system that is under load the way ours should be after having the doors open, the condenser may feel warm all the way back to the dryer. Or, perhaps only half of it may feel warm depending on heat load and design. Heat dissipation at the condenser increases with more heat load at the evaporator and decreases with less. It will take a little practice to get good at detecting it. A normal system with very little heat load at the evaporator would have very little heat dissipation at the condenser. If little or no heat dissipation is detected at the condenser and the interior temperatures are higher than normal, this may indicate a system issue but does not confirm it. That will require the removal of the evaporator cover and the observation of the evaporator. A normal evaporator should be fully frosted with hard white frost. A heavy frost or ice accumulation would indicate a non sealed system issue that is keeping the heat from getting to the evaporator. A partially frosted evaporator, with a cooler than normal condenser, would indicate a low charge. A partial frost pattern with a hotter than expected condenser indicates a normal system with high heat-load. No frost with a cool condenser would indicate a no-charge, restriction, or compressor not pumping. Overcharges are rare and seldom occur from the factory. It looks like a normal system with high heat load with suction line frosting or sweating near the compressor. The concept briefly described here is based on the tech s ability to recognize a normally operating system and to not be fooled by nonsealed system issues that can mimic system problems. In the real world this takes practice and careful observation. Listen to the customer s description very carefully and try to confirm what they are telling you before jumping to conclusions. This brief article is intended to give an overview of how an experienced technician confirms a sealed system problem by eliminating non sealed system components, and evaluating the system using both the condenser and evaporator. The key is to practice on known good systems, observing both condenser temperatures and evaporator frost pattern. In a short time you will become competent at recognizing a real sealed system problem. Bill Dillard Field Service Representative From all of us at Whirlpool Corporation, we wish you and your families a healthy and happy holiday season!