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air compressor unloader valve won't turn off.

tnmgcarbide

Diamond
Joined
Jul 6, 2004
Location
N. GA- 33.992N , -83.72W usa
air compressor unloader valve won't turn off. the comp runs fine ,but the unloader doesnt retract- it bleeds air as long as the machine is running. the "tapper" pushes" the pin on the valve to release the air.

the start-stop values work ok. i assumed the
unloader should tap at start and stop? to unload the cyliner pressure?

a "pshhhhhhh"
 
Don't know what type you have, maybe you need to kit the unloader. Last two problems I had were due to a ruptured diaphragm and bad and sticking O-ring.
 
#2 on service time.

Had one that needed a regular clean up every year or two. Never seemed to be anything actually wrong and all the bits seemed to run ok by hand but it leaked after a while. My guess was that slight dampness or entrained oil in the air event eventually got enough dust to stick where it shouldn't to cause a leak.

Clive
 
It depends on the design. Many compressors have a check valve where the air goes into the tank. The pressure switch has a bleed tube on the compressor side of this check valve to bleed the pressure off the the compressor side of the line when the motor shuts off. This check valve has gone bad on my compressor twice in the last few years. The symptom was exactly as you describe. I also had a compressor once that used oil pressure to hold the compressor valves open until the compressor got up to speed. I suppose there are probably other schemes too.
 
it is a 20 yr old campbell hausfeld 60 gal twin piston single stage , with a new "lefoo" pressure switch and unlooader .
the old one was a siemens , but they use this one now .same specs. 4 port 125 psi . never had any issues with the machine
until now .

i'll inspect the check valve. it's likely due for a new one .

thanks
 








 
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