GM Frigidaire MJ-7 thermostat and broken breaker trim questions

[TimMSU1]

Model Number

MJ-7

First time poster here, so glad to find this forum!
I inherited a Frigidaire by GM MJ-7 fridge from my grandfather and he always said the fridge worked but never turned off to cycle properly, so my first endeavor will be to see if I can tune the cold control as explained here.

My first question is, does anyone have a picture or diagram of the cold control contact points? I’m new to this type of tinkering but am a builder by trade and have rebuilt old 2 stroke outboard motors so feeling up to the challenge.

My second question is, the bottom trim between the door and the box has a hole in it and I’d like to repair or replace it. I’m guessing I’ll need to possibly track down a parts fridge for this or can I do a fiberglass type repair on the part and some paint? I plan to clean the interior, repaint the exterior, and replace the door seal if I can get the thermostat functioning properly again.

 

[TimMSU1]

I opened up the thermostat and found this guy, guessing it’s a replacement.
Also, based on my reading, that coil isn’t supposed to be just hanging.

 

[Dan O.]

guessing it’s a replacement.

Yes. At least that might make finding a replacement easier than an original. If you need a new one there's one available here:

LINK > A10-886 Ranco Thermostat

that coil isn’t supposed to be just hanging.

It should be clamped right against the evaporator. There is usually a metal plate screwed to the evaporator and the sensor bulb is mounted in between.

Try holding it against the evaporator with clothes pins or similar to see if it functions better before tampering with the actual control.


Dan O.

 

[TimMSU1]

Dan O - thank you sir for the link to the replacement thermostat!
I did some major cleaning of the fridge, reinstalled the thermostat with the tubing pushed onto the evaporator.
I had clamped the compressor down when I moved it. While I was loosening the compressor I noticed the 3 wires from the relay to compressor are in really bad shape. Seems like an easy fix so heading to the hardware store after work tomorrow.

 

[Dan O.]

I noticed the 3 wires from the relay to compressor are in really bad shape. Seems like an easy fix

I will suggest you try to do as little as possible. You never know what can happen with brittle wires and may open up a whole can of worms.

Dan O.

 

[TimMSU1]

I plan to just swap the wires from the compressor to the relay and swap the 2-wire power cord with a proper 3-wire for added grounding of the unit for safety (god only knows how the rest of this wiring is that is hiding).
I do understand the compressor terminals are very sensitive and prone to damage from torque and will tread forward with caution.
Also, to quote the Great Homer J Simpson, “I don’t have to be careful, I have a gun.”

 

[TimMSU1]

Well, to my surprise, the terminals to this 75yr old compressor were finger tight tensioned and after knocking the dust off and a few new wires, I’m staring at this!

 

[Old Fridge Guy]

Looking at your pictures I suspected you'd find a replacement thermostat since the knob is not original. The original knob would have looked like this one. Also, the two nuts at the compressor, one on each side of it, should be loosened to allow the compressor to "float" on the mounts. They only get tightened down for moving or shipping the refrigerator.

 

[TimMSU1]

So, an update, I crudely rigged the thermostat tube to the side of the evaporator to test the thermostat and am glad to report I have a properly functioning 75 year old fridge now!

I did loosen the bolts on the compressor, I can grab the compressor and wiggle it freely to feel it’s floating as intended.

I found one bracket to hold the tube to the evaporator but is there more I can or should do with it to install it cleanly and still keep it working properly?

Does anyone know where to find some replacement breaker trim or is there NOS of this piece?

 

[Old Fridge Guy]

That's the correct bracket and it appears you have the end of the feeler tube installed correctly under it. Most likely that's a universal replacement thermostat which is why the feeler tube is so long. You can just tuck the excess out of the way and as long as the tube isn't kinked you should be fine. As far as the breaker strips the best thing to do, in my opinion, is try to find a parts fridge or look on Ebay from time to time. Vintage Frigidaire parts do pop up occasionally. If you have the missing piece you can super glue it back in place. Or see if your local home improvement store has a putty you can repair it with.

 

[Dan O.]

I found one bracket to hold the tube to the evaporator but is there more I can or should do with it to install it cleanly and still keep it working properly?

While that looks to be the correct capillary tube mounting plate it does not look installed correctly. The capillary tube should run in the same direction as the plate not perpendicular. Mounted that way the tubing could be collapsed by being tightened too much or it could wear through from vibration while in use.



Ideally, the capillary tubing should not be directly on a refrigerant pass of the evaporator but mainly on the rest on the metal of the evaporator box. Being directly on a refrigerant pass could cause the control to cycle off a bit too quickly.

Does anyone know where to find some replacement breaker trim or is there NOS of this piece?

I really doubt you will but you could look for another whole refrigerator model to rob for parts. Being that old, that is fairly unlikely as well.

The most likely solution is to fabricate or fix the original. I will warn you they can be very brittle and trying to remove it may cause more damage. If you can determine the type of plastic (ABS, etc.) you can purchase plastic repair kits. Those contain solvents that can actually melt the plastic to join the filler material to the original.

Here is one from Whirlpool:

LINK > 8212572 aka WP8212572 Whirlpool Liner Repair Kit ($$$)

A commercial plastics supplier will likely sell something similar if you have one in town.

Alternately, Frigidaire has a very nice tape for covering cracks in plastic. It has a really nice plasticized finish that looks like the plastic of refrigerator liners. It could cover a repair of the hole to make it look finished.

LINK > Frigidaire Liner Tape ($$$)


Dan O.

 

[Dan O.]

BTW. Care must be taken with the thermostat's capillary tubing. You can bend it be don't crimp it or it will no longer function properly. Generally you can bend it around the circumference of a pencil but not much tighter. And don't ever cut it!



JFYI

 

[TimMSU1]

While long order times on paint, summer vacations and work have gotten in the way of this project, I’m still picking away at it. The condenser has since begun running loudly, had a sort of grinding rattle to it when I plugged it back in the other week. It does quiet back down to a medium rattle when running but I don’t want to push it. It’s in my garage now, against the wall to my family room and I can faintly hear it running through the wall. Since I’ve noticed the loud noise I’ve unplugged it. Not sure what my next steps are with this mechanically. I do understand basics of ac workings (just added r134a to my truck with a manifold). Thinking I’m going to track down someone local to check it out for me. I’m in SE Michigan if anyone on here is willing.

 

[TimMSU1]

Here is the rattle sound, it’s loud enough to hear through a 2x4 wall with drywall and insulation.

 

[Dan O.]

The condenser has since begun running loudly

You may be referring to the compressor. The condenser is just tubing holding the refrigerant.

If the sound is coming from the compressor the only things that you might be able to help is making sure nothing is rubbing against it or its connecting tubing and making sure its rubber mounts have not hardened too much with age.

Any internal sounds you'll have to live with. It may however continue to function for years to come like that.


Dan O.

 

[TimMSU1]

Yes,

You may be referring to the compressor. The condenser is just tubing holding the refrigerant.

If the sound is coming from the compressor the only things that you might be able to help is making sure nothing is rubbing against it or its connecting tubing and making sure its rubber mounts have not hardened too much with age.

Yes, I meant compressor, sorry for the typo.

I’ll check the rubber mounts.

 

[Dan O.]

Actually it looks like the bolts holding the compressor are tightened right down in 'shipping' mode. You might want to loosen them off. Hopefully the long compression hasn't been detrimental to the rubber mounts.

The compressor should basically float on the rubber mounts, absorbing vibration.

Dan O.

 

[TimMSU1]

It’s hard to tell from the video but the nuts are loose, I can feel float between the compressor bracket to the rubber mounts. I’ll try further backing them off though to see if that helps anything.

Actually it looks like the bolts holding the compressor are tightened right down in 'shipping' mode. You might want to loosen them off. Hopefully the long compression hasn't been detrimental to the rubber mounts.

The compressor should basically float on the rubber mounts, absorbing vibration.

Dan O.

 

[Old Fridge Guy]

I agree with Dan. Those compressor nuts should be looser. The rubber bushings could be worn out as well as other mounting points for the condenser. These Meter Misers will sometimes rattle a bit if they're cold or after a defrost. But the sound is higher pitched and goes away after a few minutes, once the compressor gets warmed up. This sounds, to me, more like vibration being amplified by the cabinet. Is it still cooling ok?

 

[TimMSU1]

I agree with Dan. Those compressor nuts should be looser. The rubber bushings could be worn out as well as other mounting points for the condenser. These Meter Misers will sometimes rattle a bit if they're cold or after a defrost. But the sound is higher pitched and goes away after a few minutes, once the compressor gets warmed up. This sounds, to me, more like vibration being amplified by the cabinet. Is it still cooling ok?

It does cool perfectly so far. From first plug in to thermostat cycling the unit off is about 2hrs.
I’ll loosen those up much more when I’m back in town and see if that helps.