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Defrost thermostat connector

Cannot disconnect the white connector from the defrost thermostat to the defrost heater need help I have had this ref. for less than ten years and have had service out about every 24-36 months. Service tells me not to block the air flow vents and I do not. I have replaced the control panel 3x under service warranty contracts. I think I am having defrost problems and the lack of air flow over the evaporator coil. About three weeks ago, I manually defrosted the ref. and replaced the upper fan and all was good again. For the first week the ref. actually turned itself off for a few hours and drained a little into the evaporator tray. The last two weeks, the upper fan has kept running all day and all night. The lower fan has cycled on and off.
Its been three weeks and I am having problems again. I noticed the ice starting to sweat and the over temp. alarm came on this afternoon. Turned the ref. off and removed the evaporator cover and noticed the bottom 1/3 of the evaporator coil was frozen over heavy frost. I think the defrost system is not doing its job.

Question - What controls the defrost system and how do I test the system? What else could it be. PLEASE HELP!!!!

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  • arch417 Jul 04, 2008

    Thanks for the quick reply!

    This is a photo of the bottom 1/3 of the coil just before I did a manual defrost tonight. The main build up was along the sides and bottom of the coil. The upper 2/3 was about the same as you can see in the upper part of this photo. This was the condition of the coil just after three weeks. The wife tends to leave the door open a little more than normal. But I do not think this is the main problem. The over temp sensor keeps going off and on over the past few years. I am not sure about the location of the defrost heater, but when I was drying off the extra water from the coil I did locate the Bi-metal heater attached at to a silver 3/8" pipe at the top of the coil. I am not sure the small 1/4" solid copper wire is at the bottom of this coil photo.

    You mentioned a defrost timer. Where is this located on a KitchenAid model KSRA25FKBL? You stated to turn it until the compressor turns off. Once it turns off, do I turn the defrost timer back to its original setting? What does this do?

    I purchased this unit back in Oct. 2001, do you think it may be still under warranty? How can I check to see if the freon would be covered?

    Thanks again!

  • arch417 Jul 04, 2008

    Sorry about that, I forgot I had a full scale photo. I hope this helps.

    I think the red wire is connected to the bi-metal heater. Can you confirm this?


  • arch417 Jul 07, 2008

    Thanks again for the continues good information. Since I did the manual defrost back on July 3rd, the fridge is working fine. I purchased two fridge thermometers and have been watching the temp in both sides of the fridge. It appears everything is working fine (for now). I have been watching the fridge to see if it goes into an automatic defrost cycle. I noticed went into a few cycles on July 6th, but it did not melt all the frost away 100%. Twice I was near the fridge when it started a defrost cycle but it appeared to stop the defrost cycle within a few seconds and restart the cooling cycle. However, this morning July 7th, after the fridge doors were closed all night, I noticed the fridge was not making any noise. I checked the freezer side and and saw the coil was completing a defrost cycle. It appear to have melted all the frost from the coil near the bottom.

    Is there anyway to increase the defrost cycles? You told me about the defrost timer, does this increase the amount of defrost cycles? The last time I did the manual defrost, I think I located the defrost timer with the 4-5 wires coming out of it. I recall it clipped to a 1/4" to 3/8" silver tube at the top of the coil. (see full photo above). I recall it was not making attached tight to the tubing. I remember turning it a little and clipping it back on the tubing and making sure it had a better grab onto sivler tubing. This may have been the timer and I did not even know it at the time.

    I checked the fridge and it does not have a clock or a calendar. The indoor temp is normal and normal humidity. We have A/C and that keeps it low.

    I will keep an eye on the fridge for a few weeks and see if I will have to remove the food from the freezer and remove the inside cover to gain access to the defrost timer to adjust the clock. I will keep you posted on the progress.

    Thanks again!!!

  • arch417 Jul 08, 2008

    I can only see the bottom of the coil with the cover plate back in place through the stamped ventilation grill. If I look at the bottom of the coil I can see the drain for the water. The panel is back in place and directs the air flow. I am sure the defrost thermostat was causing the problem. It was very loose when I was cleaning the coil and noticed was not clipped tight to the tubing. I made sure to make it a tight fit when I clipped it back on the tubing.

    Thanks for all the help!

    This is a great service!



2 Answers

The defrost timer is not adjustable. It is usually outside the freezer compartment. The silver thing you described is probably the defrost thermostat. It should be tightly clipped to the tubing. This is what senses the actual temperature of the coil. It will not let defrost start unless coil is below 20 degrees and stops it before the timer does if the temp exceeds what it was set for. It must sense coil temp, not air temp. The defrost timer starts the cycle. and the cycle should last at least 20 minutes before the compressor comes on again. By clipping it back on you have probably fixed the problem. Why are you able to see the coils in operation? This will never work properly if the back panel is not in place. The panel is designed to direct air flow where needed.

Posted on Jul 07, 2008

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Where is the defrost heater? If it is below the problem area, I don't think it is a defrost problem. This sounds like low freon. The symptoms of this are heavy frost on only part of the coils. Try deforsting with a hair dryer and putting it back together. Wait about 3 hours and look again. If there is frost only on part of the coils that is bad. The most this unit could defrost is every 4 hours, most are on 8 or 12 hour cycles. On most units the defrost timer shuts off the compressor and gives current to the defrost heater/s through the defrost thermostat. This thermostat is closed below 15 degrees and opens at a much higher temp after sensing the heat. This shuts off the heat usually before the timer and lets the water drip down where it should go. Then the timer turns the compressor back on and removes current from the defrost system. A common defrost problem is if the doors are left open for a LONG time or not shut all the way. Sometimes it causes so much ice that it can't melt with just one defrost cycle. This problem builds as if air flow is restricted it causes even more frost and gets worse. If this ever happens , just find the defrost timer and turn it very slowly click by click just until the compressor stops. Let it defrost , then do it again in about 2 hours. If it is a low freon problem there may still be a partial warrenty left sometimes the sealed system is guarenteed ror 5 - 10 years. Sometimes if it is not covered it is not worth fixing.

Posted on Jul 04, 2008

  • Art Hessburg Jul 04, 2008

    It is not a freon problem. The difference would be much greater. I don't have the manuel for this particular fridge. So I'm just guessing where it is. That is really not frosted up too bad. I think this is normal. Without really looking close up I can't tell where the heaters are. THey are usually glass tubes with coils inside or silver tubing that looks very much like the cooling coils. Try to find out where the wire goes into the end. and follow it around. It could have more than one heater. (If so usually connected in series) With an evaporator this tall it will pass back and forth at least 3 - 4 times. The heater won't have fins attached, it will be a solid pipe and insulated wire will be coming out the ends. It will be in between the cooling coils. The evaporator starts at one end with a larger pipe and ends in a very small tube that looks like a wire but it is not insulated, usually copper, maybe aluminum. The defrost timer is a small box usually black with a clock motor attached. It will have a plug with 4 or 5 wires coming out. It is unsually underneath behind the grill or in back in the corner by the rear legs. Sometimes they hide it in the fridge compartment behind the light cover. I believe Kitchen aide is made by WHirlpool and is probably behind the light cover. there is a flat knob on the front of the timer you will need a screw driver or butter knife to turn it. Sometimes (rarely) there is an actual knob. When you turn it to put in defrost just leave it there it will turn by itself. and start Usually defrost lasts 24 minutes and goes off 2 - 6 times a day. Practice turning the knob you want to just barely put it in defrost. If you miss it the first few times just keep trying. You can feel the click. If there are seperate heaters one may be bad. If just one its not likely. I think either the timer is slow or sticks and doesn't defrost as often or the defrost thermostat is off and cutting out early. This is not a freon problem. IF your wife has the door open a lot and your house is not air contidioned this could be a big part of the problem. The humid air causes problems. If this fridge is computer controlled (?) It might not have a defrost timer. Do the instructions give any indication to set a clock or calandar for this unit. If computer controlled it would not defrost as often in winter as summer. This is possible but I haven't actually encountered one that did this. The other possible problem is does the gasket fit tightly all around the doors? Are the doors warped, do they close tightly even at the bottom? This could cause a rise in temp and defrost problems. You may be able to get by with just adding an occasional extra defrost cycle. Another help would be to buy fridge thermometers and put them in the fridge and freezer. Buy an instant read probe like they use in food service and keep it in a glass of water in the fridge compartment. This will give a more accurate reading as it is normal for the air temp to swing around 10 degrees. The food temp stays pretty constant. The fridge temp should be between 35 and 42 degrees, freezer temp below 10 degrees or enough to keep ice cream very firm. Sometimes things placed touching the back wall will warm up a little during defrost, this is normal. Door shelf temp will be about 10 degrees warmer. Another good indication of freezer temp is the ice maker performance. It won't cycle until it reaches 15 degrees. Take the actual temp of the unit and don't trust the alarm.



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Since the heater has continuity it is good and does not need to be replaced, the other parts that can make a ref. not defrost are the defrost thermostat or the defrost control (mother) board.

To check the defrost thermostat it must be checked when cold,when cold it should have continuity on it. The defrost thermostat is in the freezer clipped to the TOP of the evaperator coil usually on the right side...this is what it looks likeoldtech2332_122.jpg

If the defrost thermostat has no continuity when cold it is bad and thusly the problem...if it is good and has continuity and already having determined the defrost heater is good..the problem is going to be the motherboard since a part of it is the defrost is the back of the ref.on the left.

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The defrost heater is only going to have power when its in the defrost mode.When it is in the defrost mode the compressor and evaperator fan motor(the one in the freezer) will be off ,only one wire,to be specific the blue wire will have voltage,also the defrost t-stat wont appear to be bad by buldging but it can ONLY be checked using a multimeter set to continunity setting with a reading of zero ohms resistiance and continunity, it MUST be cold when checked, when the evap. coil is frosted up its the best time to check it (you can unplug the ref. while checking it). The white bulllet shaped part is the thermister(electronic thermostat) and has no bearing on the defrost cycle totally disregard it as being the problem. Since you have already replaced the defrost heater if the defrost t-stat checks to be good the problem will be the main control board on the back.You can pick up a economicial meter at most hardware stores for about $10.00

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Freezer is not cold enough all food is dethawing

I'm Leo
This is a common defrost problem, The ice
is not being melted by the defrost system. he fan can't blow into ref.
Take out back panel of freezer to check for ice buildup. The coils should be clean.
There are three components to a defrost system- a heater,heater thermostat, and a timer unless you have a defrost electronic card.
Its best handled by a Technician but you could possibly do it by taking your model number to the nearest appliance parts store and asking for the parts. They are mostly located in freezer ,behind back panel on freezer coils.except the card which is usually located in ref The parts store will have info
Also check evaporator fan in freezer
Also check fan undernearh Ref in the rear
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we ll see how u need to check the defrost timer....
Before testing the defrost timer, unplug the freezer to avoid an electrical shock hazard.
A mechanical defrost timer controls the defrost cycle of the appliance. In older models, the timer runs continuously and roughly every six hours, shuts off power to the cooling system and sends power to the defrost heater. In newer models the timer advances only when the compressor or defrost cycle is running - an improvement for efficiency. As the timer advances, power to the heating element shuts off and power is restored to the cooling system. If the timer does not advance, the appliance will be stuck either in defrost or refrigerate mode, resulting in, respectively, no cooling or frost build-up.
The defrost timer is usually found behind the front grill of the freezer. It may also be found behind a cover plate inside the freezer, in the temperature control console, or behind the freezer near the compressor.
To test whether the defrost timer is simply failing to advance, locate the advance screw and turn it clockwise until you hear it click. This advances it to the next mode. If it was cooling before, it is now in defrost mode. Simply wait about 35 minutes and check whether it has left defrost mode and has resumed cooling (listen for the compressor). If it does not advance, the timer motor is probably bad and the entire timer needs to be replaced. If it advances as it should, then you can follow the steps below to test the switch electrically.
The timer is usually held in place with one or more screws. Remove the screws and gently pull the timer out far enough to disconnect the wiring connector. The connector can be removed by firmly pulling and rocking it left and right. It is not necessary to note the position of the wires because the connector plug is keyed so that it can be replaced in only one way.

Test the timer for continuity using a multitester. Set the multitester to the ohms setting X1. The timer has four terminals. Locate the common terminal, it should be labeled "3" or "C". If the terminals are not labeled, determine which terminal coincides with the common wire in the connector plug; it is usually the white wire.
Once you have located the common terminal, touch one probe to it. Touch the other probe to each of the three remaining terminals. The multitester should display a reading of zero or near to zero ohms (which indicates continuity) for one pair of the terminals and possibly two pairs. The third pair of terminals should show no continuity (infinity).
Locate the timer switch and turn it clockwise until you hear it click. Now retest the timer as you did above. One pair of terminals should indicate continuity (possibly two pairs). At least one pair should give a reading of infinity. Note however, one of the pairs that showed continuity in the first test should now read infinity and one pair that read infinity should now show continuity. If the defrost timer does not pass these tests, it is likely that it should be replaced.

Before testing the defrost heater, again make sure u unplug the freezer to avoid an electrical shock hazard. The defrost heater is located at the back of the freezer. It may be necessary to remove obstructions such as the contents of the freezer, freezer shelves, ice maker and the rear or bottom inside panel of the freezer. The rear panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way. The heater is connected by two wires.Label the wires and connections so that you can properly reconnect them later. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire itself). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If either is corroded they should be cleaned or replaced. Test the heating element for continuity using a multitester. Set the multitester to the ohms setting X1. Place a probe on each terminal. The multitester should display a reading somewhere between zero and infinity. If the reading is not between those two extremes the heating element should be replaced.

this is how u check the thermostat..... again Before testing the defrost thermostat, unplug the refrigerator to avoid an electrical shock hazard. Some defrost systems use a thermostat (a bi-metal switch) to prevent the defrost heater from overheating. The switch is normally closed. During a defrost cycle, the defrost heater causes the metal alloy in the switch to warm and as it does it curls back and breaks the circuit. As the metal cools, it makes a circuit again and the defrost heater starts heating again (as long as the defrost timer is in the defrost cycle). A defective thermostat can prevent the defrost heater from coming on or allow it to overheat which could result in heat damage or fire. The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky -never force it. If you decide to remove it, you do so at your own risk - it is prone to breaking. Try warming it first with a warm, wet towel. The thermostat is connected by two wires. The wires are connected with slip on connectors or a wiring harness. Firmly pull the connectors or harness off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced. Test the thermostat for continuity using a multitester. Set the multitester to the ohms setting X1. Place a probe on each terminal. The multitester should display a reading of zero when the thermostat is cold and a reading of infinity when it is warm (40 to 90 degrees F depending on the model). If the thermostat does not pass this test it should be replaced. with regard to the parts incase u need a replacement..... check out the below link....

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1 Answer

Defrost thermostat connector

There is usually a little tab inside the connector. Use a small flat blade screwdriver and pry into the center of the connection where one slips over the other. If you warm it up with a hair dryer it may pop apart easier. If it is rusted, burnt or corroded, just cut it off and use orange wire nuts to make the connection. Use electrical tape to seal the nuts. 

Jan 09, 2008 | Refrigerators

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