Hi. 15 year old Amana SXD22S2W side-by-side. We lost power for 15 hours. We used a generator a few times in that period to run the fridge. Said generator caused a number of power strips to blow, so I wasn't completely surprised when a few days later, I noticed the ice cream had melted:-(

After power was restored, the first symptom was that the water dispenser stopped working, though the ice dispenser did work. I shut off the circuit breaker for a minute and that fixed that.

I opened the inside back panel and the coils were completely iced over. In this model, if you press the door switch four times in eight seconds, it is supposed to start the defrost cycle. This seems to work. That is, I do hear a fan (condenser fan?) turn off. I think the heater coil does heat up.

But all this time, the evaporator fan doesn't turn on. I saw it turn on once when I turned the inside cool switch from off to about 5.

I think it's the control board. How do I confirm?

(Oh, this may be that power-saving evaporator fan that's prone to failure, but what exactly should I look for?)

Thanks!!

Here are your parts
Replacement parts for SXD22S2W models | AppliancePartsPros.com

See the attachment for the tech sheet. The wiring diagram for your unit is on Page 12.
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I think the heater coil does heat up.[/COLOR]
You cannot guess on whether the heat comes on, you have to be sure.
Remove the cover inside the freezer so you can check the defrost cycle.
If the heater does come on then you still have a defrost board problem as it is not starting a defrost cycle since your coils were heavily iced up. Also could be the defrost thermostat is toast. See below on how to check the defrost.
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I think it's the control board. How do I confirm?[/COLOR]
You have to check the defrost to make sure that the defrost thermostat and the heater are OK.
To check the fan check for 120 volts across it. If there is 120 volts and it does not run it is toast.

[COLOR="DarkRed"](Oh, this may be that power-saving evaporator fan that's prone to failure, but what exactly should I look for?)[/COLOR]
It is not a power saving fan but a standard 120 volt fan.
[COLOR="DarkRed"]
How do I test the evaporator fan? There are three connectors: hot, control, and ground to the chassis. Can I short the control to ground?[/COLOR]
No this may be a dead short.
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Or, can I test for a broken control board by testing the resistance between chassis and the black wire that goes to the thermostat to see if it's open?[/COLOR]
Not sure what you are doing here. Chassis under normal circumstances is not part of the circuit.

On this unit the evaporator fan gets power through the heater circuit when it is not in defrost mode.
N neutral - WH wire -m Def Htr - DF Ther - BR wire - left side of Frz Fan - FRZ Fan winding - YLwire - Cold Cntrl - RD wire - hot side of line.

DEFROST CHECK
First remove the evaporator cover in the freezer so you can see the coils.
Do not let them de-ice.
If they are heavily iced/frosted over you have a defrost problem.

If yes.
Manually force a defrost cycle, see the tech sheet.
When the fans and compressor turn off you are in defrost.
Now check the defrost heater to see if it is on.
Be careful you do not want to burn your fingers.
If the heater is on then the defrost board needs replacing.

If not on.
Unplug the unit.
Remove the wire for one side of the heating element from the wiring and measure it for continuity, usually around 20 ohms or so.

If the heater is OK
Remove one wire to the defrost thermostat and measure it, should be 0 ohms when frozen. Note that it opens just above freezing so must be frozen to check it. Also inspect it, if it is bulged at all replace it even if it measures OK.

If both the above are OK then odds are the defrost board is toast.
Best way to test this is a live test to see if you have 120 volts across the heater/defrost thermostat combo.

I would give them a call.
Who knows they may have a source for them or may be able to suggest a place you can get one.

[COLOR="DarkRed"]When I disconnect the heater, the fan turns off. I think this means a problem with the board at T.[/COLOR]
No it should turn the fan off.
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The fan is getting its voltage through the heater.
(I can't tell from the wiring diagram where the fan is supposed to get its Brown voltage from. D should be open because we're not in defrost mode.)[/COLOR]
Yes the fan does get it's voltage through the heater.

It gets it's Brown voltage (Neutral) through the heating element.
The circuit path is N neutral , WH , DEF HTR , DF TERM , BR , FRZ FAN motor winding , YL , COLD CNTRL , RD , H line voltage.

When in defrost mode the fan motor is basically shorted out, see the connection between C and K on the timer.
The defrost thermostat and heater now see the full 120 volts across them.
N neutral , WH , DEF HTR , DF TERM , BR , D timer , K timer , COLD CNTRL , RD , H line voltage.

When in a cooling mode the resistance of the fan limits the current through the heater so that it does not drop much voltage. The tech sheet shows 2 fans and I am not sure which one your unit uses but even if we use the higher wattage (12 watt) (0.1 amps) the heater would only drop 2.9 volts across it, [0.1 (amperage draw) times 29 (heater resistance)]. So the fan gets (120 - 2.9) 117.1 volts. Therefore it dos not heat up the element but the fan runs.

You could measure the voltage across the heating element.
If it starts out at about 3 volts and then rises to 90 volts (120 - 30) then you know that your fan is drawing too much current and probably needs replacing.

I hope I explained the above OK.

[COLOR="DarkRed"]Is it possible that the heating element is bad? Do these things break?[/COLOR]
Yes the heating element could be bad and they do break (open). A heating element is basically just a length of wire. It is nichrome wire that has resistance so when current flows through it, it heats up. Since it is a straight piece of wire they do not short out but the wire can burn out causing an open.

[COLOR="DarkRed"]But I measured the resistance of the element, and it starts at 20kohms, and slowly moves up to 300k! Is this because my little meter doesn't generate enough voltage to accurately show the resistance?[/COLOR]
The reading is way too high it should be around 20 ohms.
Since you can read 20 Kohms you should be able to read 20 ohms.
Use the most sensitive scale when reading it. Also short the meter leads together before starting so that you know the meter is working.

[COLOR="DarkRed"] Or is there some funny thing wrong with the element?[/COLOR]
Looking at your reading of 20 Kohms, there is something wrong with it.
I would replace it.

[COLOR="DarkRed"]Also, and maybe this proves it, the heating element does NOT heat up when in defrost mode. I'll test the measurement again.[/COLOR]
Yes it sounds like it is toast.
Also check the defrost for bulging. If it is bulged replace it even if it measures OK.