On most models, when you open the refrigerator door, the evaporator fan shuts off (and a light turns on) , via a door switch. So when troubleshooting the evaporator fan, you must open the door and press the door switch. If there are two door switches, one is for the fan and one is for the light.
Mini-refrigerators usually DON'T have an evaporator fan. Air circulates by natural convection; the warm air towards the bottom of the fridge rises and is cooled by the evaporator. Once it gets cooler, the air sinks and is replaced by warmer air from below.
Open your freezer door, press the fan door switch and listen for the evaporator fan.
If you do not hear it running, there's a problem.
If you hear a "warbling" or "whistling" sound, the fan bearings are bad. Replace as described below.
Even if you do hear the evaporator fan running, but you do not feel a strong blast of freezing air from the freezer vents, then there's a problem. Usually the ducting is choked with ice, slowing or stopping airflow.
It might be jammed with debris from the freezer, or blocked with ice, or it might have just worn out and stopped. The door switch that operates it might be defective.
If there is frost covering about one-third to one-half of the evaporator, it normally indicates one of two problems.
If thick frost is clustered around the evaporator fan, the fan motor is usually running slowly, or not at all. It might just be the door switch that failed, or it may be the motor itself. If the motor is worn out, it may or may not still rotate, and it may or may not be making noise, but it is still worn out. If the fan motor is running slowly, it will show the same symptoms.
In any case, we need to open the evaporator compartment and check the fan for problems.
Remove any access panel or tower within the freezer that houses the fan.
Now we need to remove some panels to see the frost pattern on the evaporator. So let me ask you a few short questions.
Do you have a side-by-side, a top-freezer, or a bottom-freezer machine?
Remove everything from the freezer, including any shelves.
On the back or bottom of the freezer compartment, there will be a removable panel with a bunch of screws holding it in. We need to know if you have a back-panel freezer, or a bottom-panel freezer.
Remember which one you have. You will be using this info for later diagnosis.
Remove everything from your freezer, including all food and any icemaker and shelves.
Look at and feel the panel covering the back of the freezer compartment. Is it thick with frost?
Are there air vents in the top of the food compartment that are choked with ice?
If the answer is yes to either of these questions, there's probably a defrost problem.
If you suspect a defrost problem, first remove any icemaker that may be installed. You will see a removable panel covering the entire back of your freezer compartment. There may be 6 to 10 or more screws holding it on. In some units there is a light socket attached to the panel.
These can sometimes be quite difficult to disassemble. Make sure the power is off the refrigerator before disassembling any lighting circuit.
The panel may be frozen to the evaporator beneath it; be careful you do not bend or break it. Sometimes it pays to take a few extra minutes and melt the ice a little bit first. This can usually be accomplished by blowing warm air on it with a blow-dryer. Do not melt all the ice just yet; only enough to get the panel off. You want most of it to remain there at this point so you can further diagnose the problem.
NOTE: There is something behind the panel called a "terminating thermostat." You don't want to heat it up until after you make your diagnosis. Therefore, it's a good idea to try to avoid melting any more ice than you have to... just enough to get the panel off. If the thermostat opens before you've had a chance to see if the heater works, you'll have to by-pass it. On some models, this involves cutting, stripping and splicing wires. No big deal, but
it's an extra step that's unnecessary if you're careful about melting ice in the first place.
There may be some styrofoam insulation panels. If so, they may be waterlogged and may break when you remove them. It's okay, just keep them in one piece as much as possible and replace them as best you can when you're re-assembling.
You will see a removable panel covering the entire back of your freezer compartment. Is it thick with frost? There may be 6 to 10 or more screws holding it on. In most units there is a light socket attached to the panel. We need to remove this panel.
NOTE: There is something behind the panel called a "terminating thermostat." You don't want to heat it up until after you make your diagnosis. Therefore, it's a good idea to try to avoid melting any more ice than you have to... just enough to get the panel off. If the thermostat opens before you've had a chance to see if the heater works, you'll have to by-pass it. On some models, this involves cutting, stripping and splicing wires. No big deal, but it's an extra step that's unnecessary if you're careful about melting ice in the first place.
Look at and feel the panel covering the bottom of the freezer compartment. Is it thick with frost?
Can you see airflow holes that are choked with ice?
Is there ice forming on, or lots of water on the ceiling of the food compartment?
If the answer is yes to any of these questions, there's probably a defrost problem.
You will see a removable panel covering the entire bottom of your freezer compartment. There may be 6 to 10 or more screws holding it on.
On some models, you may have to remove some of the plastic moulding around the door frame to access some of the evaporator panel screws. Be extra careful; the plastic moulding can be brittle and break easily. The plastic will bend; just go slow. You may even try heating it a little with a blow dryer, to soften it.
The panel may be frozen to the evaporator; be careful you do not bend or break it. Sometimes it pays to take a few extra minutes and melt the ice a little bit first. This can usually be accomplished by placing a pan of very hot water in various places on the panel, or by blowing warm air on it with a blow-dryer. Do not melt all the ice just yet; only enough to get the panel off. You want most of it to remain there at this point so you can further diagnose the problem.
Look at the frost pattern in the evaporator compartment. You should see one of these frost patterns:
1. Thick frost covering just one or two of the evaporator rows, and the rest of the evaporator is CLEAR OF FROST.
2. Thick frost covering just the top of the evaporator, or maybe one row of coils, and the rest of the evaporator is LIGHTLY frosted.
These first two frost patterns are fairly easy to confuse with each other.
Both have a lot of ice build-up on the first few evaporator coils.
The difference is whether the rest of evaporator is fairly evenly frosted, or not frosted at all.
3. White, solid ice, or thick hard white frost at the evaporator inlet.
4. The frost seem to be caking inside the evaporator fan and ducting.
If your answer is #1 or #3, that's a bad sign. It means that some of your Freon has leaked out. You will need to call a refrigerator service technician to recharge your sealed system. Depending on the cost, it might be worth it to just buy a new refrigerator.
If your answer is #2 or #4, then the ice needs to be melted, and the fan or door switch needs to be replaced. Even if the fan is running, it might be turning too slowly, which would cause this same symptom. Melt all the ice from the evaporator compartment, then check the fan and door switch as described below.
If nothing is blocking the fan and it still does not run, either the door switch or the fan motor is bad. Or both.
You can use a voltmeter to check for voltage across the fan motor leads (with the door switch pressed, of course.)
ARE YOU ABLE TO GET TO THE MOTOR TERMINALS TO TEST THEM?
IF NOT, go back to the last step and click "I will need to remove some more panels to get to it."
If you don't have voltage to the fan motor, the door switch might be bad. Take power off the fridge and pry out the door switch. You might have to destroy it to get it out. You can just touch or jumper the two switch terminals together. If the fan runs when you do, then the door switch is bad. Replace it.
If you have voltage across the fan motor leads, but it's not turning, the fan motor is bad. Replace it as described below.
SLOW RUNNING EVAPORATOR FAN MOTOR
Sometimes the evap fan will run slower than it should. This can be difficult to diagnose. It can cause ice to build up in the internal ductwork. If you have ice in the fan duct, but not on the evaporator, this may be the case. You will need to replace the fan motor.
If you hear a "whistling" or "warbling" noise coming from the fan motor itself or from the inside of the food or freezer compartment, it is probably coming from the evaporator fan motor. The bearings are worn and loose or sticky. Replace the motor.
As I said, a slow evap fan can be very difficult to diagnose. Usually it is done by sound and by experience. The chances are, if it sounds slow or strange, it is malfunctioning. Try replacing it. They don't cost much.
Fix the Evap Fan
REPLACING THE EVAPORATOR FAN MOTOR
To change the evaporator fan motor, first unplug the refrigerator.
In replacing the fan motor, you must make sure that the rotation of the new fan motor is the same as the old one. The easiest way to do this is to look for the shading poles on the old fan motor.
If they are on opposite corners from the ones on the new fan motor core, it is a simple enough task to reverse the new rotor in its core. Carefully remove the bearing cage screws and simply turn the rotor around so the shaft sticks out the other end of the motor.
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