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A few weeks ago my children started complaining the ice cream was too hard. I set the temp level in the freezer to 2 and all was fine for a while. Last week I noticed the compressor running for extended periods. In the past there was a duty cycle of less than 20% during warm weather. It appears the only time it is off now is when the defrost coils are on. The fan at the top of the evaporator also runs constantly at low speed, never high speed as it used to do when the door was opened too long. The compressor is pretty warm but the condenser coils are barely above room temperature.
The settings are now 1 for freezer and 3 for fresh foods. During the day the freezer stays at about 10°F and fresh foods between 32-40°F, at night when the door is not touched they get lower.
The condenser coils at the bottom were cleaned in the spring, I have cats so this is a regular procedure. The defrost coil was changed from the original single tube to the new double tube about 4 years ago after a freeze-up.
Any suggestions? temperature sensors (2 in freezer, one for fresh foods)? Main circuit broad?
KaptJaq
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Rank: Advanced Member
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Hi. Check if the evaporator coil is covered evenly with the frost. If it is, test the freezer temperature sensor. At 10F resistance - 31.08 KOhms and at 77F - 4.92 KOhms. Replace the sensor if it's out of the range. In case if the evaporator coil is not completely and evenly frosted (with condenser fan running) you've got there a sealed system problem. The freezer thermistor Part number: WR55X10025
Good luck. Please keep us posted with the results. Thank you, Simon.
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Rank: Member
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Hi Simon,
Thanx for the reply. There are two temperature sensors, one at the bottom of the evaporator coil and the other at the top. The one at the bottom tests good. The one at the top is harder to get to...
When I realized the condenser coil was not hot I began to think there was something wrong with the actual refrigeration loop. The compressor housing is at ~145°F and the condenser coil is <95°F. Room temperature is currently 81°F.
Does the difference in temperature between the top and bottom sensors control the fan speed?
There is more frost on the bottom of the evaporator than the top.
KaptJaq
EDIT: I pulled the back evaporator cover. Within 2 minutes after I pulled the cover, with the compressor & fan running, near the bottom of the coil it is about -2°F. Near the top it is almost 30°F.
KJ
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Rank: Advanced Member
Groups: APP Team
Joined: 2/12/2012(UTC)
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Hi. The top sensor is controlling the defrost cycle initiation, the bottom one is the freezer sensor. Once more, you need to determine if the evaporator coil is frosted completely or only partially. Touch the top row and the bottom row with wet finger. it should stick to the coil. If it does, most likely you need a new control board. The main board Part number: AP4436216
Keep in mind that you can return this board back to us within one year installed or uninstalled. Thank you, Simon.
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Rank: Member
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Hi Simon, Did I add this part of my message after your reply? Originally Posted by: kaptjaq 
EDIT: I pulled the back evaporator cover. Within 2 minutes after I pulled the cover, with the compressor & fan running, near the bottom of the coil it is about -2°F. Near the top it is almost 30°F.
KJ
If the sealed system is working correctly and the refrigeration loop & evaporation fan are running for several hours shouldn't the freezer get very cold, well below zero? Do you think the temperature of the compressor, 145°F, is normal? KaptJaq
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Rank: Advanced Member
Groups: APP Team
Joined: 2/12/2012(UTC)
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Hi.
The temperature measurements you took are not really relevant in this case. If you can determine that the evaporator is frosted completely and the freezer thermistor is good then the most likely the main control is faulty. If the evaporator is not frosting up COMPLETELY then it's a sealed system problem. Also, if the evaporator is blocked with snow at the bottom it may indicate the defrost failure. If this is the case, test the defrost thermistor and the defrost heater.
Thank you,
Simon.
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Rank: Member
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Hi Simon,
The refrigerator is currently not running so I cannot get the thermistors down to 10°F. I tested the thermistors at room temperature and in a cup of ice water. At 75°F the were just about 5k ohms, in ice water the were about 14k ohms. Do you think this is close enough to eliminate the thermistors? Should I just order the control board?
Thanx for the help,
KaptJaq
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Rank: Advanced Member
Groups: APP Team
Joined: 2/12/2012(UTC)
Posts: 5,556
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Hi. You have not said anything about the evaporator frost pattern. If it's a sealed system failure the new control board won't help. If the evaporator is frosting completely, then yes, you should try to replace the control board. Thank you, Simon.
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Rank: Member
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Joined: 8/7/2015(UTC)
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Simon,
Yes, when the unit is running, the evaporator has frost from bottom to top. The frost at the bottom is a little heavier than the top but I assume that is because the air enters from the bottom and loses moisture as it moves up.
It is not thick enough at the bottom to restrict airflow so the defrost works.
KaptJaq
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Rank: Advanced Member
Groups: APP Team
Joined: 2/12/2012(UTC)
Posts: 5,556
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Hi.
Sounds like the thermistors are OK, unless you have an old type with round end and black epoxy sealant at the thermistors' end where the wires coms out. If you have an old type, replace them too.
Thank you,
Simon.
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