Window A/C Compressor in Refrigerator

[Coke45]

I am installing a used window a/c compressor in a refrigerator. The refrigerant I will be using is 134a, the oil will be Ester, (converting from R12-old refrigerator to R134a) what I need to know is, what viscosity should I use? The compressor that came out of the old window unit had R22 in it, what viscosity oil do they use in window unit air conditioners​ with R22?

Checking oil pressure: there are only two ports on this compressor - High and Low, do I check the oil pressure by subtracting the high from the low, or am I missing something? Any advice?

The compressor from the window unit is too tall to fit into the refrigerator, so I welded some small casters to the mounting holes so it will roll and be easy to move when it comes time to clean behind it. No, you can't get it as close to the wall as before, but it will work and be easy to move.

[mikeref]

A/c compressor will not be suitable for low back pressure applications, such as your fridge. Your fridge compressor has to be replaced by another within a 5% tolerance of original compressor's cooling capacity.

[Brian_UK]

You cannot measure the oil pressure in a small compressor like that, they work on the 'splash' lubrication principle.

[monkey spanners]

Emkarate RL32 or equivalent. If its a rotary compressor you may not be able to get the old oil out.

[Coke45]

A/c compressor will not be suitable for low back pressure applications, such as your fridge. Your fridge compressor has to be replaced by another within a 5% tolerance of original compressor's cooling capacity.

Sorry for the limited knowledge, I don't know much about compressors - I know some of the basics (apparently not all the basics); now I see that some have oil pumps and some don't, like lawn mower engines.

The a/c compressor is 10,000 btu - 1/4 hp, and so is the refrig. So, a few more questions: What is it with the back pressure, and, can I use cutoff valves to regulate it; maybe a cut-off valve on High and Low side, and then their is using a larger line/filter to reduce back pressure?

If small compressors are splash lubricated; how much oil do I use and what if I get too much, how do I know, and how do I remove it? Is it just a guessing game without manuf. info. The a/c compressor is a Fedders, and their defunct. The comp. sticker says: Configuration: G-AJS, LRA: 55, REFR: R22. What is the LRA referring to?The rest of the sticker is rubbed off - I don't know if this will help any.

[Brian_UK]

LRA = locked rotor amps, similar to start current.

You need to check your calcs, 10,000btu is 4hp not 1/4 so your bolt on compressor is 16 times oversized.

[Coke45]

Thanks Brian, I was never good at math. I looked it up online; I see the mistake now, I divided it "backwards".

I'm a bit confused . . . the a/c system seems about the same size as the refrig., except for the smaller diameter condensing coils on the refrig., the evaporator, I think is about the same size. Why is there so much difference in the compressor size, from one to the other?

If I had an a/c compressor that was 1/4 hp, is there any chance that it would work?

[Brian_UK]

Why keep trying to find ac compressors, why not try and find one for the fridge?

[Coke45]

I'm just trying to salvage an old fridge in a pinch - I have another a/c compressor from a smaller a/c; I just thought if it would work it would save me some money. But if it is just too far off, then I won't bother.

[FreezerGeezer]

Iirc, the rating of the compressor is actually the cooling duty of the system, not the compressor power.
Since the lower the suction temperature, the greater the suction:discharge ratio a .25HP refrigeration compressor has to be more powerful than a .25 air con compressor. Walk into the average supermarket Plant room & you can instantly tell which is the HT pack & which is the LT - the latter has bigger compressors.

[Coke45]

Yes, I noticed that the size of this a/c compressor was much too small to be 4hp, it's more like 1/4 - 1/3 hp. I have a 1/2 hp motor on the lathe and it dwarfs this small compressor. But I did not know that refrigeration compressors were more powerful than air con. compressors - that helps! So, if I used this compressor, even with cut-off valves to regulate flow, it might not do well unless it is a 1/3 hp comp replacing a 1/4hp comp. Thanks for the information guys! If you can think of anything else that might help - feel free to comment.

[shanonmethod]

I my opinion window AC compressor is not working properly in refrigerator because the both working panel are different between each other.Refrigerator is low power consuming and compressor parts are different from AC compressor. So its not a right way to fit compressor on refrigerator.