Roper RT21LMXKQ01

[OAR]

This is a new one on me. Freezer temps are up and down all  over the place. Had the customer keep a log over the past 3 days and there is no pattern of time to temp. Elderly retired couple no kids or house guest leaving door open. I'm guessing electronic defrost controll has gone squirly but i've never seen one act like this before and I dont know how to verify proper operation. Please HELP!!!

[Chat_in_FL]

[user=8993]OAR[/user] wrote:

I'm guessing electronic defrost controll has gone squirly

 Also could be T-stat sticking, or sealed system issue, or evap fan... Attached file is how to force defrost:

[Budget Appliance Repair]

I can almost garantee you that it is the ADC board.

I have an older Roper which uses a board very much like yours, same wiring and labels but different part#, (probably different defrost programing is all).

I got my frig used from the scrapyard becuase is looked in good enough condition to take home and replace mine.

I plugged it in and it appeared as all was working fine then had it running and it kept shutting down, I thought I had a bad molex connector down by the compressor because it seemed everytime I would touch the wiring around that area it shutdown.

So, I pulled the connector apart and cleaned and tighted all connections then it seemed to work ok. Took my old frig out and put this in the house and loaded it with food and later that night it starts doing wierd things again. Once I went to sleep and everything was quite I heard it start a few times then stop and try to start again real soon and kick off on the overload.

Started messing with it and started to hear click noises corresponding to the unit shutting down and then trying to restart and traced the noise to be coming from the ADC control area.

This was like 5-6am in the morning so, I pulled the ADC board and direct jumped the power to compressor on the board connector, (leaving board out of system so no defrost functions), and it ran perfectly all night.

So I just replaced the ADC with a standard 8hr 21min defrost timer, It will plug directly into the harness connector the ADC board plugs into but you have to remove one wire form the plug and swap it with one of the other wires that won't be used, (It was either the neutral or L1 wire that had to be swapped to use the mechanical defrost timer in place of the ADC).

[OAR]

Thanks for the replies guys.

Evap fan is working good, not sure about thermostat, i've never seen one stick and release over and over again like that. I've only seen them fail fully closed but I'm not that experienced. My Pops, an old timer appliance guru, also suggested a sealed system issue but I can't see why when the customer is logging good temps 2-3 times a day. Maybe I should just shut up and listen to the voice of experience:? 

One of you mentioned replaceing the ADC with the old style electrp-mech timer. Exactly how is that done and how do you know which terminal to use with the flying lead?

[Budget Appliance Repair]

That's where your tech experience and being able to read the schematic comes in!!!!!

If you use the mechdefrost timer with the flying lead, set it up like you would for a continuous run timer.

The way you can rule out the t-stat is to bypass the ADC board, remove it and put a jumper wire in the connector that plugs onto the ADC board, again you will need to be able to read and understand your schematic to know what two wires to jump to bypass the defrost, (It will be the L1 line that supplies the 110volts to the ADC board and the COMPRESSER Wire, I believe that would be the orange wire).

With the ADC out of the system and bypassed the unit should work fine if the problem was the ADC board. With no defrost system the unit should operate for 4-7 days before it plugs up with ice and starts to stop functioning correctly.

If the frig works ok for at least 2-3 days after bypassing the ADC, you can be sure that was your problem.

I looked up the wiring diagram and attached it to this post:

The wires are in this sequence: 2-PK(Pink-defrost), 1-BK(Black-L1), 4-OR(Orange-Compressor), 3-RD(Red-?compressor run signal?) --- 5-BR(Brown-Defrost termination sense), 6-WH(White-Neutral)

To bypass ADC - Jump 1 & 4

To convert to mechanical defrost timer, remove #4 red wire from 4 plug connector and remove #6 white wire from 2 plug connector and swap those two. The two plug connector is just left unplugged and the defrost timer is plugged into the 4 plug connector, (both of these two plugs us a different wire spade connector holder so the white wire won't lock into place in the 4 plug connector, just make sure to seat the wire fully onto the defrost timer inside the connector block).

Also, if you do decide to replace with mechdefrost timer, please note what you did on the wiring diagram so if someone comes in after you they will know what is up.

[OAR]

Thanks Budget!!

How did you find that schematic?

Schematic was missing on unit just like 15% of the appliances I work on out here. There are serveral huge scratch and dent appliance warehouses in my county and I think they pull the tech. sheets out before they sell them just to P me off!!!

  Customer called back yesterday and said temps now have been holding steady in the low teens for the past 2 days. Makes me think there might have been a loose con. or a sticky thermostat. That's really the only thing I touched.  Chalk it up to another mysterious fix that I don't get paid for:?

[Budget Appliance Repair]

For Whirlpool products you can usually find the tech sheets and wiring diagrams here: http://servicematters.com/docs/doc_main.htm

[OAR]

Hey,

Thanks for that!!!

now I just need to get wireless internet service so I can download those while in the feild.