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by Ronald Norris
(Altoona, Pa.)

I wanted to make a “silent air” compressor out of my HF oil compressor. I took off the original (new) motor and replaced it with a motor/compressor from a fridge, so far so good.

When it runs the air keeps running out of the unloader valve. I tried to do this to 2 new compressors (oil) and still the same thing, I got no air in the tank. I gave up on the oil compressors.

I bought an oil free one, took off original motor hooked up the fridge motor/compressor. Started no problem but the compressor wouldn’t shut down at the 100 lb. mark it kept running. Also there was an awful high pitch sound coming from the area around where the air enters the tank.

I taped around the threads and it still did it. I really need a “silent air’ compressor because I do t-shirt airbrush work and I just got people that moved in below me about 1 month ago so I can’t use any compressor now. Oh, I checked the tank valve on the oil compressors they seemed to be okay. Also checked the unloader valve actuator valve pin, seems to work. Need help!!

Ronald, your concept of using the refrigerator compressor is brilliant. A small (joke) company called Jun-Air built a compressor company doing basically what you are doing.

Tank check valve inserted into tank with unloader line inserted into fitting. (Blue air line)
Tank check valve inserted into tank with unloader line inserted into fitting. (Blue air line)

From what you are telling me, I suspect that the tank check valve is not working.

It’s supposed to keep the air in the tank when the unloader trips to dump the air over the piston when the compressor stops.

If the check valve is failing, tank air bleeds out of the unloader valve. That it’s whistling suggests that the flap hasn’t seated all the way.