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Jimontheroad · 05-02-2021, 04:19 PM

I've been prepping the motorhome for an upcoming extended tour. Today was the first time I've attempted to crank up and test the A/C units. Here is what I have:

* 1992 Fleetwood Pace Arrow
* Selector switch for front and rear A/C units
* Front works fine on Onan 7 KW generator
* Front works fine on 120V AC only (20A circuit with extension cord)
* Rear A/C inop on generator
* Rear A/C inop on 120V AC extension cord
* All fuses/breakers are fine

NOTE: I hear it humming to itself with generator off and on AC shore power, but no fan, and no cooling. Selector switch on unit does nothing. I DID NOT attempt to run the A/C on generator power ONLY.

Questions:
If the front A/C works fine on shore power, why wont the rear work?

I don't know if the two units are different in power or other requirements

Could I have a blown starting capacitor in the rear unit? It hums slightly when power is applied, but changing the selector switch on the unit has no effect.

Is there another way to isolate and test the power going to the rear A/C unit?

It's getting kind of warm out there.

Old-Biscuit · 05-03-2021, 12:42 PM

Can you turn on just the Fan for the Rear A/C ??
Does it run?

Start Capacitor
Run Capacitor
Locked rotor...bad motor
Does rear A/C get 120VAC power.

Jimontheroad · 05-03-2021, 04:37 PM

Can you turn on just the Fan for the Rear A/C ??
Negative. Neither selector switch (operation and temperature) on the unit makes any difference in any position other than "OFF".

Does it run?
I can hear it hum slightly when on shore power. Generator is too loud and vibrates, but I suspect it's humming on generator power as well.

Start Capacitor
Spoke with my A/C guy this morning. He suspects caps as well, either start or motor cap.

Run Capacitor

Locked rotor...bad motor
AH! Hadn't thought of that one, but looked for blown breaker, and all are good.

Does rear A/C get 120VAC power?
Yes. confirmed by plugging and unplugging it in and listening for hum.

Rsponsford · 05-06-2021, 11:16 PM

My guess is the start capacitor. I would change out both the start and run capacitors. You can also test the capacitors but they are cheap enough it’s hardly worth the trouble.

steppinstone · 05-08-2021, 02:49 AM

I had a similar issue with mine so I took the cover off and was looking for broken wire or something out of the ordinary. I grabbed the fan and it was stuck so I freed it up by turning it back and forth squirting pb blaster on it and it works fine now...give it a shot can't lose..