C/H shuts off at 50 psi and won't restart

by Gary Bowers
(Okc, ok. USA)

WL651600AJ pump and motor

WL651600AJ pump and motor

I have a C/H model WL651600AJ. It builds pressure to 50 psi and shuts off. Bleeding off air doesn't make it restart either. I've replaced the pressure switch assembly but that didn't change anything. Any suggestions? Thanks

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Jul 27, 2015
Heat and compressor motor
by: Bill

"Can heat cause the seperation?"

Gee, I thought I addressed this in my last response?

Jul 27, 2015
Round and round
by: Gary

Bill, I'm trying to state that the voltage reading at the motor side of the switch does read 117 volts in both on and off modes. So there's suitable voltage going to the motor even after its stopped. It's always at 50 psi. With no other device to cause this it almost has to be the motor itself. Almost! I say this because it doesn't make sense to me that a motor just stops at the same point without any external forces. Can the windings separate after warming up? I suppose I could disconnect the voltage wires, set my dvom to ohms and see what the resistance reads. Or doesn't read I should say. Can heat cause the seperation? Thx

Jul 27, 2015
Power from switch to motor
by: Bill

If your air compressor stops before it reaches the normal cut out pressure setting and you have power to the pressure switch and from the pressure switch to the motor you still have power flowing, then the problem is not the pressure switch. It's doing what it is supposed to... sending power to the compressor motor so that the pump builds pressure in the tank.

As to the point where the motor stops, you indicate that it's always at 50 PSI. Compressor motors work harder as the pump works against the steadily building pressure in the tank.

What I suspect is that your motor is overheating while the compressor is pumping, at that it shuts down at 50 PSI is a result of how long it runs until the pressure reaches 50 PSI, rather than it being the 50 PSI that causes the shut down, if you follow.

In other words, it takes xxx amount of time running for the motor to overheat. That just seems to coincide with the time it takes for your compressor tank to reach 50 PSI.

In the absence of a capacitor on this compressor motor, it were mine, I'd be looking at a new motor.

However, since the new motor and pump assembly appears to cost more than the compressor does new, it may be time to replace the compressor with a new one, and keep any serviceable parts from failed one as spares.

Jul 26, 2015
Motor?
by: Gary

At the switch there's the line coming from the wall and another going to the motor. Both of these read 117 volts when running and when shut off. My question is this, how can a motor run to 50 psi, maintain acceptable voltage, and yet shut down, and yet fail to restart unless manually switching, without having any external means of reaching this point? By this I mean switching or valving. Is it possible for the motor to run one minute and then stop the next? Always at the same time! Thanks

Jul 26, 2015
Electrical issue
by: Bill

Is the power getting past the pressure switch even though the air compressor is not running?

What do you mean by testing the voltage to eliminate the motor?

If the pressure switch is good, and power is flowing to the motor, and the motor is not running, then it's pretty much got to be something in or the motor itself that isn't working properly.

Jul 26, 2015
What's next
by: Gary

So after replacing the switch and testing the voltage to eliminate the motor, what do I do next? Thanks for the help

Jul 26, 2015
Voltage
by: Bill

Gary, when you say "The readings were 115 at both locations" are you saying that even when the compressor is stopped, you are getting a voltage reading on the wire to the switch, and still getting voltage on the wire from the pressure switch towards the motor?

If so, then I stand corrected (again!) from my earlier comment.

The compressor issue must be power related, and if the power is getting through the switch when the compressor shuts down, then it isn't the switch that's the issue, but something at the motor.

Jul 26, 2015
WL651600AJ pump and motor
by: Bill

I've uploaded an image of the WL651600AJ pump and motor so all can get a look at what you're talking about, Gary.

It would certainly appear as though this motor, if it is the one on your WL651600AJ, does not have a start cap, being a pretty small motor.

And I agree. Based on what you've written, that lets out the motor as the likely culprit.

Jul 26, 2015
Voltage test
by: Gary

As requested I checked the voltage when the compressor shuts off. The readings were 115 at both locations. You had stated that it may be a capacitor if this was the case. Unfortunately there doesn't seem to be one on this motor. Now my question becomes this. Can the motor function fine one minute and repeatedly shut down at the same psi time after time? Thanks

Jul 25, 2015
Voltage check
by: Gary

I checked the voltage on the switch and it reads 117 on both sides. You stated that it's probably the capacitor. Where is this contraption? I've looked all over to no avail. I can't see it being the motor itself cause that would be either it works or doesn't right? Thanks Bill

Jul 05, 2015
Capacitor
by: Bill

All of your questions are already answered on the pages of this site, Gary.

Please see the troubleshooting pages and read up on the one about capacitors, testing capacitors, etc.

Did you determine if the pressure switch was tripping off, or not?

Jul 04, 2015
More questions
by: Gary

Thanks Bill for the suggestion. Just where is this capacitor you're talking about? I can't see a brand new switch being bad. How would I test this capacitor? I thought they just stored power for initial startup? Heck, I don't know. I guess if I did I wouldn't be doing this eh? Anyway, thanks for the help.

Jul 04, 2015
WL651600AJ shutting off
by: Bill

Gary, you need to know if, when the compressor shuts off, is it the pressure switch that is shutting off power to the motor, or is the motor shutting itself down?

Use a multi-meter to check on the motor side of the pressure switch next time the compressor stops.

If there is power on the motor side of the switch, that tells me that the switch is good, and now, it points to the motor as being the issue.

If this were my compressor, I'd be looking for a weak or failing capacitor, as long as the pressure switch is still passing power when the compressor shuts down.

Bill

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