Frigidaire Evap Fan motor not working

[jumptrout51]

Evaporator fan motor was burned out. Installed a new fan motor. It did not work. Reading 106 volts at molex connector in freezer section.
When you connect the fan motor volts go to "0".
Efan motor volts come from the defrost control.
If you initiate defrost 120 volts are read across the defrost terminals. That side of defrost board is putting out full voltage.
My question is: can the defrost control be bad on the e fan leg causing the lower voltage?
and why does voltage go to "0" when the good fan motor is connected?

Model frs26r2aw3

[JWWebster]

I do not know for sure but it may be that the evap fan ain't gonna kick in until the terminator gets down to 25 degrees
Just a guess.

[jumptrout51]

The neutral wire splits at the molex connector.
One wire goes to the defrost terminator, the other to the neutral side of the fan from the molex connector.
The defrost stat wire then goes directly to the def. heater neutral side.
My first thought was the same as yours, but it is not wired thru the def. stat.

[Al Capone]

Here is the wiring diagram.

Wish I could be of more help.

[whirlpooltech]

I would replace the Adaptive Defrost Control (ADC)
Unless there is a bad connection someplace I don't see how it could be any else.

[jumptrout51]

I would replace the adaptive defrost.
Unless there is a bad connection someplace I don't see how it could be any else.

That is exactly my thought.
But, for learning purposes...why does voltage drop to zero when the fan motor is attached to its wire leads?

[whirlpooltech]

Have you looked at the defrost board for any damage?

I see a lot of these boards get damaged from power surges and from compressors that short out.

Hard to say sometime with electronic boards why they do what they do when they are bad.

[whirlpooltech]

It does not help that we only get a block diagram for the adaptive defrost from Frigidaire.

[jumptrout51]

This house did have a voltage spike according to the electrician.
This call occured yesterday Saturday at a beach house awaiting the arrival of 10 house guest.
Being a holiday weekend I did the only thing I could think of to get them by until next week when more parts would be available.
I drilled a hole thru the back of the freezer compartment, attached a cord to the fan motor and plugged in to a wall outlet.
I will be going back next week with a defrost control.
I am certain this will correct the problem.
I still want to understand the voltage absence when the fan motor is plugged in.

[RegUS_PatOff]

Electronic devices sometimes do that when they go bad.
It may be able to supply 106v with no load (or a very small load), but when the fan is connected, the amperage that the fan needs is too high for the (failed) electronic device.

The same thing would happen if you connected a high value resistor in series, such as a 270K OHM, with the 120v line and measured it with your meter, but then when you connect a load, such as the fan, it would drop to nearly 0 volts.

You could temporarily connected the Evaporator Fan to pin E3, so it only runs when the Compressor & Condenser Fan runs.

You wouldn't want it to run when the Defrost Cycle runs (if that still works)

[JWWebster]

From the diagram that Al posted I would say the fan runs through that crappy defrost board that we all have been saying for years should not have been mounted inside the icebox. Change the adaptive defrost control or at least yank it out and clean the green corosion off the teminals with alcohol and reinstall it. It might start working.