2/3 dryers not blowing air on IBA

[pmullens1985]

I bought a car wash and both automatics have 3 air dryers and on both of them the outter 2/3 dryers aren’t working so 4/6 total. I’m not sure where to even start. Or if this was a way the prior owner could pinch a buck. I can’t be sure.
thanks In advance for any help.

 

[MEP001]

Start by checking for power to the motors...

 

[soonermajic]

Start by checking for power to the motors...

Yep, check the relays first.

 

[Greg Pack]

after checking to make sure there is power going to the motor starter check to see if the overload has tripped. Reset and see what happens.

 

[Ryko CS]

Systems will be different, but most dryers use an overload and contactor. For the contactor, you will have a control voltage that should cause the contactor to pull in it's contacts even if your 3 phase is off. Are you getting your control voltage to the contactor when it's being told to start? If not, check wiring back to the PLC. If the contactor is able to pull in, you need to check your 3 phase.

Do you have 3 phase at the top of your contactor? When the contactor pulls in, you should have 3 phase voltage at the bottom of the contactor. If not, it could be burned contacts or an overload tripped.

 

[Sound_Boi]

Also check to make sure the voltage is the same across all 3 legs. I've had a a breaker go bad on one of my blowers and the voltage on one of the legs was 83 when it should of been 208.

 

[pmullens1985]

after checking to make sure there is power going to the motor starter check to see if the overload has tripped. Reset and see what happens.

Overloads tripped upon resetting tbey trip immediately on firing the motors again. Unfortunately. But manually firing each individual motor they at least run so that’s a good start

 

[pmullens1985]

Also check to make sure the voltage is the same across all 3 legs. I've had a a breaker go bad on one of my blowers and the voltage on one of the legs was 83 when it should of been 208.

They were exactly the same across oddly enough which really boggles me why they’d trip immediately after reset

 

[MEP001]

That's a bad contactor. If you're pushing the contacts manually and they run, but they trip when they come on with the signal, the coil isn't pulling the contacts together properly and the motor is "single-phasing," not getting power from one of the three lines.

 

[Greg Pack]

Do you know how to use a voltmeter? If so, put one lead on the "upstream" terminal of each contactor and another on the "downstream" side below the overload. Ideally the meter should read 0 volts when the motor is running. If you find a significant difference in voltage that could be your problem.

Also, not a bad idea to revert to the basics of turning off the power and checking/tightening all connections from the breaker panel to the motor terminal box.

 

[pmullens1985]

Thanks so much. On It!