Air Conditioning Issue

EMS, not ECM system. IF the compressor is indeed turning ON and then turning OFF, then the capacitor is not the problem. The problem is probably a bad compressor and the compressor overload is kicking it out. But, a Capacitor is a cheap quick attempt without having the proper tools for a correct diagnosis. Does your EMS have an AMP readout? If so, watch the amp readout when the compressor starts and then kicks out. That will tell you what the amp draw is on the compressor after start up and it is running for that few seconds. IF it starts and runs for a few seconds and the amp draw is higher than 15 amps(amp draw added with other amp draws), the compressor is bad.
You look at the EMS readout with the ac off and lets say it reads 17 amps. You start the AC and you will see a 3 amp added for the fan motor-- now you show 20 amps. When the compressor kicks on you will see a spike above 50 for a millisecond, as the start capacitor kicks it on. Then, IF the amp reading is over 33 to 35 amps when the compressor is on and then slowly rises, then your compressor is bad. Doug

The units are controlled by an ECM for both units inside the coach. I can run either separately and the rear unit runs just fine by itself. It's only the front unit that has the problem. The rear AC and the generator play very happy together. I'll take a look at the start capacitor tomorrow. As soon as I figure out how to get the covers off. Thanks for the link to the troubleshooting manual. It was working just fine a couple of days ago. Chuck

here is a manual. run the troubleshooting pages.

http://bryantrv.com/docs2/docs/rvp/rvp6789mech.pdf

Do you have a switch to run either the front or rear AC inside the RV, if so switch it the rear one and ensure the generator is working correct. Then run thru the troubleshooting pages. I agree it sounds like the start/run cap.

Sounds like the start capacitor is fried..easy fix...plenty of posts about it if it is a dometic...make sure you ground out the capacitor before you work on it..it is under cover on roof and you will see it probably fried.

it's a Coleman good chance a hole got rubbed in the tube and its toast.You can get a regular ac guy to fix the hole and recharge it if you want to take that chance

newman fulltimer wrote:
is it a Coleman ac?

The manuals that came with the coach say RVP. Chuck

is it a Coleman ac?