compressor wont shutoff/build pressure

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BILL WARD

SGF, Supreme Grumble Framer
Joined
Mar 25, 2004
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2,451
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Tampa, FL
My C.H./5HP/15GAL/OILESS just went fritzzy after 2years+. Turned it on, closed the bleed, as usual, started getting stuff ready...took awile for it to sink in....it wasnt shutting off! Flipped the on/off to off, motor stopped, flipped it back to on & it didnt some on(as the pressure was up). a little while later it came back on(small leak in a fitting), but it didnt shut off and the pressure didnt build to the shutoff setting...........anyone have a idea whats going on????(other than Im in the market for another one?)

thanks for input
 
Sort the small leak first, but the shutoff setting may be set too high.

I have a Bambi - the pressure used to get too low before kicking in - if I had an ash (e.g.) moulding to pin I would have to let pressure out so it kicked in. I solved that by adjusting the setting (no idea how to do that on yours - on mine I remove a cover (disconnect from mains first!) and adjust a +/- screw) so it kicked in earlier.

Trouble now is that it does what yours does - it keeps going until the safety valve scares us all ****less - well, usually we hear it start to hiss and turn it off. The earlier (higher pressure) it kicks in, the later (higher pressure) it cuts off, could yours go lower before kicking in? If so, adjust it down.
 
My compressor acted up last year at this time. Just wouldn't shut off....
So off to HomeDepot went I! Couldn't be without it during the XMas rush. They were out of all the little ones so now I have a huge compressor! Its loud sure, but I feel like it doesn't run nearly as much. Now I hear that they have "quiet run" compressors for sale!
 
It might be the pressure control unit that needs to be replaced. The unit is easily replaceable.

The unit consists of pressure sensors and relays to turn the unit on and off.
 
I don't know if your compressor is like my three. One, I made from an old walk in freezer compressor forty years ago. One is a little two gallon tank I bought last year from Sears. But, they all have a shut off switch that you can adjust. There is a little box sitting on the top of the compressor that you can lift the lid off. It is smaller than a recipe box. It may be under a plastic cover. Inside there are two switches that look like rocker arms (Kind of ) with springs. the points may be stuck together or the springs worn. I just sand the points or adjust each of screws like john did. I would bet the points are stuck.

The points on the old compressor stuck one night and ran for 10 hours before I caught it. That was one hot compressor! I sanded the points smooth so they wouldn't arc - and it's been reunning since.

Another problem I have had is if you run plastic lines - they often split or break at the connections and leak away from the compressor. You don't hear the leak so you assume the problem is the compressor.

Mitch
 
If it won't shut off and the pressure isn't building to the normal shut-off pressure either the compressor itself is worn out (getting too much blow-by on the rings) or there is a leak somewhere. Since you don't mention that the compressor has been running a lot more than usual lately, most likely it's a leak.

The leak could be in the piping between the compressor and the check valve where it goes into the tank, so you won't notice that leak with the compressor shut off. Try (carefully, it's HOT!!) running your hand along where the piping goes while it's running to see if you can find a leak there.
 
In a sister/parallel post Bill noted that it was the pipe between the compressor and the tank.

Having worked in the past with true High Pressure Compressors (4 stage 2000-5000 psi) I always make a practice of not using my hands to test for leaks. Granted at 85-100 psi there is little or no danger other than a slight burn, but if somehting happens that the pressure increases significantly... I have known those that lost digits to extremely high pressure leaks from very small orifices which acted as a knife. As I said this was working with extreme pressures, but I always take the safer way and run a sheet of paper up and down the length of suspect piping and use soap around fittings and joints.
 
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