Amana Refrig Strange problem

[Wedgeman55]

Hello,
      I have an Amana Refrigerator that is really giving me a headache.  Model is SRD25S5W,  manufacture # is P1190302WW and serial is 9508244097.    I've been working on refrigerators since the early 70's and never had a problem like this.     I came in,  no evaporator fan was running.    I checked power at fan,   none.   Replaced the Defrost limit which was popped out.    Then checked again,   no power.    I replaced the adaptive defrost board,   and the ECM evaporator fan.    (the new fan was a straight 120 volt fan,   which showed to be the replacement. )    It worked slightly,  but fan was only running slowly.   Found only 50 volts at fan.    Then I replaced the adaptive board again,  figuring I had a bad board.     Nothing.   Still no volt to fan.    ON the cold control side where wire goes to evap fan,  I get 110 if I measure from White L2 to yellow from fan,   so I know I have a neutral problem.  I've check all the harness wires.  None burned, or broken.    Thought it might be one of door switches in freezer,,  but those are OK>   Any ideas anyone???   Thanks in advance for your assistance.

[Repair-man]

Go around back, take the steel cover plate off the back which  covers the heat exchanger going up to the evaporator. You will find the wiring harness there and the Neutral connections can be checked. I have found lots of wiring issues there, due mainly to the sweating of the lines.

[Wedgeman55]

I already had the back plate off.    Checked wiring at connector block and all of the wires.      Thing is,   When I read the schematic and checked the voltage at the adaptive board,   I didn't have the power there either.     Between orange and yellow,   I should read 120 and I'm getting 26 volts.    Seems like control board issue but I've already put in 2 boards.     Something may be screwing up board,   I'm ready to drive my head into wall over this one.   

[Repair-man]

There has to be one spot (probable in a pinch-point) where the wire has degraded inside the insulation of the wire. Have a good look behind the control harness where it goes into the cabinet liner also. You may have to pinch out a grommet to get to them.

Are the interior lights also affected by this voltage drop?

[RegUS_PatOff]

Looking at the non-ADC Board models (and I believe in this model also)

The Evaporator Fan gets it's Neutral through the Defrost Terminator and the Defrost Heater (is it good?)

[JWWebster]

Reggie that means if the heater is good then the system has to get down to terminator temp(25f approx) before the fan comes on. So therefore the fan will NOT run until the freezer gits all propah. Am I correct in your thinking?

[RegUS_PatOff]

correct (somewhere around that tempearture)..

no use blowing the air until the Evaporator gets cold after Defrost ...

[Wedgeman55]

I was aware of the defrost thermo.   I had a new one and put that one in also.     Forgot to mention.     I checked with meter after it cooled,  usually takes about 10 minutes before defrost fan comes on.   I'll check those wires tomorrow.      I couldn't think of anything else.    Thanks for the ideas.   

[Wedgeman55]

I'll be back at the house today to check this out.   I downloaded the bulletins from service matters yesterday,   and I'll let you know what I found.   

[Wedgeman55]

Well,  SUCCESS,  finally!!!  Time for a few fresh doughnuts to celebrate.     
I went back,  and I was armed with the voltage check sheet for the adaptive control board.    Checked all voltages.    Started checking all the wiring between control board and components.     All seemed fine.    I narrowed down the problem to neutral side of the fan.   
Fan was reading anywhere from 34 to 50 volts.     
Once I ran out of ideas, for the hell of it,   I plugged in another heater.    Not the exact one,  but one for a maytag.    THAT WAS IT.    Somehow the heater was grounding out slightly on the evaporator coils,  and was causing voltage drop.    I had ohmed out the heater earlier and just forgot about it.     
Went back,  installed the new heater,   closed it up and is now working fine.   Valuable lesson learned.    Check out the defrost heater.   
Again,  thanks for all your help,   I always appreciate it.  I've been doing repair work for 36 years,  and this shows you can always learn something new and nobody knows everything.
One other thing to remember.    I never give up on a problem and neither should any of you.    With perseverance you can fix anything. 

[RegUS_PatOff]

...Somehow the heater was grounding out slightly on the evaporator coils, and was causing voltage drop ...

acutally, that would give the Fan more of a Neutral ...
It may have been a bad connection somewhere (or still)

[JWWebster]

Right ON Wedge

[Repair-man]

Methinks if the heater was indeed grounded, then there would have been a sllight amount of heat produced, just like on a dryer element. This may have prevented the bimetal from closing properly. ??

[RegUS_PatOff]

One side of the Defrost Heater is connected to Neutral (unlike Dryer Heaters)

If part of the Defrost Heater shorted to ground, it wouldn't cause any problems
until the Defrost Timer sent power to the L1 side of the Defrost Heater ...

[Wedgeman55]

I agree with the more of a neutral comment.   All I know,  is 3 days later,  refrigerator is working good.    I called to check on it.     All I know is,   next time I get a similar problem,   I am gonna try out a new heater early.    Lesson learned.     
Among today's jobs========
Had an easy day today compared to the refrigerator.   Did a seal and bearing job on a Speed Queen Commercial washer,   of course everything was frozen together.   Nothing a 4 inch cutter and a chisel couldn't cure.   
Then,  did and old GE washer 2 speed clutch job (don't get many of those anymore),  again on a commercial washer.   DIRTY JOB
And for a kicker,   Had to crawl into a pit in a laundromat and clear out a blocked drain, in my high boots.   
AND IT STILL  WAS LESS AGGREVATING THAN FIGHTING WITH THAT AMANA REFRIGERATOR.