AC problem

[ajm12]

Hi all
Can anyone get me some incite on the possible problem.
My front rooftop ac will not run. when turned on the fan comes on the the compressor kicks in. then the circuit breaker pops. Noticed that when the compressor kicks on the amp draw goes over 60 amps. Just wondering if the compressor is shot. It is a coleman 15,000 roof air conditioner.

[PandK]

You probably have a compressor with a seized shaft, On the Dometic units I have there is no way to rotate the compressor shaft by hand, I would suggest you try to do that (power OFF of course) but expect it cant be done.

[hometool]

it could be the compressor or posibly a bad capisator or a broken wire. need to access unit and ckeck it out lee

[ajm12]

well the compressor is a closed unit. There is no way to get to the shaft. What i was wondering is if the compressor was shot or not.

[mrtinker]

NOTE......TURN OFF ALL POWER TO THE UNIT FIRST!!!!

Disconnect the three wires from the compressor shell terminals. (Label and Remember where each goes!) then set your multimeter to the "ohms" scale... the symbol looks like a little 'horseshoe'.

Test your multimeter before you start (touch leads and verify "0" ohms).

Touch one lead to a good chasis ground on the compressor, then touch each lead... if you get zero ohms from one or more of the terminals to the chasis ground.... then your compressor is shot... if it reads "infinity" then your good... then you'll need to check the windings themselves for short or open.....

Take your leads across two of the three terminals... you should get the following readings... or thereabouts:
A-B=1.3 ohms
B-C=2.9 ohms
A-C=4.2 ohms
your reading the start winding, the run winding, and then the two added together....

Hope this helps, Let us know what happens....

mrtinker

[mrtinker]

Note, if the compressor windings check out okay and it turns out your compressor shaft is siezed... there could be another component causing the problem... the capacitor... if that checks out then you may need to install a "hard start capacitor" in the circuit too, but be aware that this would only mean your on borrowed time if it comes to that...

Good luck!

[ajm12]

Thanks mrtinker i will try that in the morning.