OT: Air Compressor Trouble

[Hec In Omaha]

Howdy all,

I am hoping someone out there can help me. With all the mechanical/electrical knowledge in this forum I am sure I will be pointed in the right direction!

I have a 4 HP, 13 gallon Campbell Hausfeld oil less air compressor. If there is no pressure in the tank, the motor will start right up and run until it reaches it's 125 PSI cut out. Once it has pressure in the tank the motor will always trip the breaker when it tries to restart or if I try to manually start it. I always have to bleed the pressure down to zero psi to get the motor to start again.

As always all information is greatly appreciated.

Hec

 

[souNdguy]

might be a start cap.

I hads a buddy that had one like that. what he did was installed a t in the line and 2 ball valves. one valve isolated the compressor head from the tank. he's shut that to preserve whatever air was in the tank. the other valve was onthe orphan end of the t.. this vented the compressor head to atmosphere. he'd start the compa dn then swing the valves, making sure to lag close the vent to atmosphere by a fraction of a second behind openign the tank to head.

this worked.. but the real fix was getting her to start properly.

i saw a cheap chinese pump that had a cap wire burn thru.. saw it arcing. it had a hard start issue before that. would ALWAYS trip a thermal breaker upon starting.

soundguy

 

[Tom Beddard ENC]

I ve got a 3hp pancake compressor that will do the same thing if I use a cord that is too small. Try a larger cord or use a different circuit to be sure it is getting enough power. They use more power at startup with pressure on it than it does at 0psi

 

[Hec In Omaha]

Sound Guy,

I think we are on the same track in that it is mechanical and not electrical? I suspect it may be the check valve installed between the tank and the compressor head. If it does not seat the compressor will always have pressure on it during start up which would over amp the motor. To test I will let compressor run until it shuts down and bleed some pressure off. Next I will disconnect the line from the head to the tank, at the head, and see if I hear any hissing. If its hissing the check isn't holding. If there is no hissing I guess that could mean the unloader valve is not working.

Hec

 

[Hec In Omaha]

I am running this compressor directly off an outlet. No extension cords. The circuit breaker is a 25 amp on the circuit. The motor on the compressor says it will need 15 A protection. I can use my big 30 gallon compressor off the same outlet with no problems at all.

Hec

 

[souNdguy]

i'm actually betitng on electrical.

one cheap comp i had had no check in it.

still 2-3 possibilities.

 

[Beanmedic]

Had a similar problem with mine. Was surprised to find that the motor was turning, but it was so quiet I couldn't hear it. Made it sound as if it would only run when zero pressure. I was thinking it wasn't running because the air pump wasn't turning. Found that the pulley was misaligned and belt slipping. Aligned pulleys and eventually replaced the belt with a segmented one to get satisfactory operation.

IF the motor won't turn, I'm also betting electrical. Start capacitor would be my guess. Something else to check, if wired 220 volt, make sure you are not just getting 110 volt to the motor because of a problem at the supply, breaker or starter switch (depending on what setup you have).

 

[Ken Pike]

Might be the unloader valve that releases pressure from the compressor head when it shuts off,so the piston doesn't have to compress cyl. full of air when it restarts. You can usually hear them bleed off when the compressor stops.

 

[Geo-TH,In]

I agree with Ken. The unloader valve may be on the pressure switch. There should be a lever on the switch so when the switch shuts off, it will push down on the unloader. There is an adjustment on the unloader. If not bend the little lever down, you should hear the pressure pleading off the piston. Let us know what you find out.
George