Air Compressor won't stop running

[rkluck]

Looking for any possible ideas on what may be going on. The air compressor (a Husky) runs and will not turn off. It starts and builds pressure correctly and at around 155 PSI the safety relief valve pops. I have switched the Pressure Switch twice (I thought maybe the first one was bad) and it still doesn't cut off. Both switches match exactly to the original switch even the same number on the switch. I swapped the safety relief valve with another one and it didn't change anything. That told me the that pressure being displayed is correct. I made sure the air tank hole to the switch wasn't blocked (I ran a wires about 2 feet down in the tank. I had it running and pulled the wire off of the Pressure switch and it stopped so I know there is no bypass or short (highly unlikely). One leg of the 120 power goes the switch. The other side goes to the motor. Very simple! This is so simple that I am sure I must be missing something. I am getting another compressor but still want to figure this out. I thought about getting another switch that cuts off at 130 PSI but even if that works, it just isn't right. It is possible that i received two bad pressure switches but thought that would be unlikely although right now that is seems to be the most likely option.

Anyone run across something like this before? Thanks is advance for any thoughts!

 

[zipper]

Is the pressure switch adjustable?

 

[Cobra Jet Steering LLC]

Is it a 110 or a 220 v If it is a 110 does the switch cut both wires or just 1 and if it only cuts one is it cutting off the hot side and is the black wire going to the switch and did someone rewire it and accidently reverse the black and white wires if so that may allow the green wire to complete the circuit to ground and That is dangerous as you could actually complete the ground if you are handling any metal part and something that is grounded, as you would complete the circuit and get a shock big time. Use a meter and be sure the wires are not reversed

 

[FSH 210 Sport]

Was this compressor functioning correctly in the past?

 

[Neutron]

Check the relief valve may be weak and blowing too early. Hold it in and see if it turns off on its own. They do fail and are replaceable. Should be rated at 175 not 155

 

[rkluck]

Thanks for all the responses. This worked fine until the day it stopped shutting off. The power is 120 and one side of the power (both wires are black) goes to the switch and one goes to the motor to compete the circuit. if I pull the wire off the switch that is going to the motor while it is running the motor stops. The pressure switch is not adjustable. I did switch out the relief value with another one and had the same results. But I never tried to hold it in. I may try that just to see if stops. The switch is supposed to come on at 120 and off at 150.

 

[AZMark]

Make sure your wires are in the right spots and that it’s not actually adjustable internally. That would be rare to get 2 bad switches in a row.

 

[zipper]

Check the exhaust tube for cracks. Common failure for husky/ch compressors. The tube may be cracked near the fitting at the head. If not, it could be the Teflon coated piston ring has a crack.

 

[Cobra Jet Steering LLC]

Use a volt meter and be sure the wire being cut off by the switch is the wire carrying the power and not the return wire if someone changed the cord or plug on the wire they may have it wrong also use the meter to confirm that there is NO continuity through the switch when the correct p s i is reached obviously your safety valve is confirming that the P S I is correct I still believe the wire to the switch is the wrong one and a meter can confirm that quickly

 

[Marvin willis]

Mine did that. The contactor switch is sticking.

 

[rkluck]

Thanks for all the responses. The wiring was good. I tied the safety valve closed (this was a little nerve racking) and the compressor shut off around 165. So the safety value must be bad even though I had swapped it out already. I am guessing the PIS dial is a little off as well. Bottom line I am going to get a safety valve and now have two air compressors! Thanks again!