Air Compressor trips breaker under load - Campbell Hausfeld - VT6290 20GAL

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Old 10-22-13, 02:11 PM
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Air Compressor trips breaker under load - Campbell Hausfeld - VT6290 20GAL

If I remove the belt the motor runs fine, spins freely as does the compressor pump. With the tank pressure empty, the compressor starts and runs fine. When it reaches 125psi, it shuts off and I hear the unloader valve hiss a small amount of pressure. When I then draw down the pressure to around 85psi, the pressure switch kicks the compressor back on and it tries to start, hums for a few seconds and trips the breaker. If I manually draw down the pressure with the switch off between 85psi and 50psi, it trips the breaker. However, if I draw it down to 40psi and turn it on, it will in fact start and run back up to 125psi.

I suspect that the following are ok but am looking for advice before part shopping:

- start capacitor is fine (runs with no load, from 0psi up to 40psi)

- unloader valve is fine (hear it activate immediately upon compressor shutting off and appears to relieve pressure in the line between pump and tank)

- pressure valve? I think it may be fine as it kicks in at the prescribed 85psi and activates the compressor to turn on

- Check Valve looks like the suspect and may be allowing air to return back to the pump, but I have no idea how to verify.

Any thoughts?
 
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Old 10-22-13, 04:30 PM
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To ascertain if the check valve is holding run the pressure up until it stops and unloads. Unplug the power cord and wait for an hour and then see if the compressor pulley still turns easily OR disconnect the unloader tubing from the pressure switch. If the compressor turns easily or if no pressure (no air) escapes from the unloader tubing then the check valve is okay. If you do not have an unloader tubing from the check valve inlet to the pressure switch then you obviously cannot do this second test.

start capacitor is fine (runs with no load, from 0psi up to 40psi)
This means nothing as it takes very little power to start an unloaded motor. Once it starts the capacitor is removed from the circuit. Your problem could very well be the starting capacitor.
 
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Old 10-23-13, 05:44 AM
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Furd, thanks for the information. I'll test the check valve as you've suggested.

I've ordered a replacement start capacitor (just in case). While I've tested it with an ohmmeter, I don't have a meter with a capacitance setting to verify its within the proper micro farads range specified on it. For $10, its definitely the least expensive place to start.
 
 

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