Ex fridge motor problem

Good afternoon everyone,

I have a spare fridge motor which I want to reuse as a small compressor. There are three pipes from it, one of which was attached to the thermostat, one is crimped off (which was used I believe to allow filling with refrigerant) and the third one is open. My question is which would be the proper one to use as the output as both have air coming from them. Any suggestions would be much appreciated, Many thanks,

John Weight.

Put your finger over the ends of the open tubes, one should suck, one should blow. Use the blow to fill your cylinder. If that is not the case I would suggest that your compressor is not well.

Is it an old motor. It could be goosed. I remember dad making one using an old fridge comp & a fire extinguisher for the tank. It does need oil though in the sump. So not much good for painting without a good trap fitted. There should I am sure be only air coming from one port as it has a reed valve in there. To add, look on youtube as I think some have cut the outer body away which is only there for the refrigerant. 

Steve.

Edited By Steviegtr on 07/03/2020 16:11:22

https://www.youtube.com/watch?v=7cRS91c8f7w

....One of the best 'make a fridge compresser' vids

What an excellent video particularly the filter made from a door knob.

Martin P

Unless you know that the old fridge doesn't have Freon refrigerant please don't just chop the pipes on an old fridge and let the gas out, it causes breakdown of the ozone layer

Hi, a cautionary note, you should never put your finger or any part of you body, over an opening of compressed air. Compressed air or any compressed gas can pass through your skin and get into your blood stream, which is something you do not want to happen.

Regards Nick.

I would add to Duncan's comment,

Don't release the refrigerant from ANY fridge (or similar device). If it is a domestic unit it almost certainly contains CFC's. It is an offence to deliberately release CFC's as well as being bad for the environment and a potential health hazard. If it's not a CFC it will be ammonia which is a serious health hazard.

For the OP, if the two ports do not have obvious suction and pressure (pressure should be at what you are calling the "thermostat" which I'm guessing is the expansion valve) Then the compressor is faulty. Most likely a valve failure, but could be a fractured pipe or badly worn.

Any fridge compressor need oil for lubrication SAE 32 hdraulic oil used for nmany lathes e.g. Nuto 32, is fine.

If using one of these compressors you MUST fit a safety valve of some sort. If the pressure switch fails (or if left running if you did the unspeakable and don't have a pressure switch) they will generate very high pressures. The running pressures are much higher than the static pressure the compressor will start at and can run to hundreds of PSI due to small piston area and large rotating inertia.

Robert G8RPI.