Community Forums

Stretch · 10-04-2014, 10:54 PM

Our coach has 3 roof airs. They all work. However the front and middle draw 15 amps as they should. The rear draws 18 to,19 amps and occasionally shuts down prematurely. Then starts up again. Question is; is 18 amps way out of line? Is it about to fail?

Gorlininc · 10-05-2014, 02:54 AM

I'm not an AC professional but I say your compressor is drawing too much current and overhearing and shutting down. I'd say it's on it's way out.

jettyjock · 10-05-2014, 04:31 AM

Make sure the condenser coils are clean and straight. If the get clogged or dirty the pressure will get high and make the compressor work harder.

Okiedoke · 10-05-2014, 04:54 AM

Our similar situation turned out to be a blower motor with worn bearings. Replaced it and unit runs better than ever.

wa8yxm · 10-05-2014, 05:10 AM

Most RV roof airs are in the 10-15 amp range, However.....

Earlier this year (lik 3 months ago) one of mine started tripping it's 20 amp breaker, Clamp on said it was hitting 21 amps (no wonder it tripped) went topside the next morning before the sun entered blast furnace mode (Which it was doing 3 months ago, temps in the tripple digit range in the afternoon/evening) and pulled the covers, cleaned a while bunch of "Stuff" off the condenser coils (Air blows from inside to outside on these. so you need to remove covers) replaced covers and came back down.. Turned it on and though.. just now it is off, (52 degrees out I do not really need it) has not tripped a breaker since.

Back to 13 amps

Bedroom air is most often used.. I'm guessing it needs cleaning.. in any case, that should be the first procedure following initial diagnosis of excess current draw.

jacwjames · 10-05-2014, 08:45 AM

I had a similar situation on my front air, when it was trying to start it would kick out and then restart on it's own. We started to just leave the blower running on low all the time which seemed to help. I had already installed a hard start capacitor.

I had cleaned the AC unit earlier this year so I didn't think that was the problem.

After our last 6 week trip I took the time to go ton the roof and inspect. It seemed like the front AC blower motor was tight so I ordered a new one and replaced. When I got the old blower motor off I found that it was essentially seized up, once I got it turning it did turn but with much resistance. The bearings are not replaceable, after I got a new motor I tore the old one apart, both ends were failing.

The new blower motor, once installed would free wheel fairly easily.

Sounds like you have a blower motor going (or gone). Mine was a Duo Therm by Dometic. I went to this website to get the current part number as searches for the blower motor using my original parts list wasn't successful.

https://www.edometic.com/allusr/sp.nsf/spc?readform

I found a wide range of prices on a replacement motor so it pays to shop around, ended up getting a good deal on one from Adventure RV that had been a store return, cost $105 including shipping. PPL had them for $125.

The replacement was pretty straight forward. Just took time and ~20 trips up and down the ladder to complete. While I had the unit apart I cleaned the condenser good with a air compressor.

Good Luck

Stretch · 10-05-2014, 03:22 PM

Problem is , the fan motor runs both the condenser fan and the squirt cage evaporator fan. So if cold air is coming into the coach I have to conclude that the fan motor is turning. But got me thinking. Tomorrow I'll set all three A/Cs on "fan only "stat setting and compare the amp usage of each unit. That will tell me if I have a compressor problem or fan motor. What do you guys think?

R&J · 10-06-2014, 01:57 AM

IF you fine the fan (blower motor) running slower then the others and cutting out Check out the fan run capacitor.
Rich

Stretch · 10-06-2014, 09:45 AM

Thanks for all the good ideas guys. I'll ckeck it out and let you know.

Stretch · 10-07-2014, 04:31 AM

Tested all three unit in fan only mode. All three showed 2 amp on the clamp on meter. Shows fan motors not the problem. Right?

RustyTools · 10-07-2014, 05:46 AM

Can you get the clamp-on meter around a compressor wire? Likely won't be able to catch the start-up current surge, but maybe to see what run-draw is. And then compare it to the others?

Does sound like a failing compressor, unfortunately.

YC1 · 10-07-2014, 06:09 AM

Shop WEB Coil Cleaner at Lowes.com

As WAX suggest. A good cleaning will make a difference. I use this stuff on my radiator and engine AC condenser as well. It works so well I bought ten cans because it seems when a product works well they pull it from the market.

jettyjock · 10-08-2014, 05:49 AM

If you use a coil cleaner make sure it is made for the condenser and not the evaporator, also make sure it is not acid based. Since you cannot hook up gauges to see the pressures you can use a thermometer to measure temp leaving condenser and compare to another one. If higher , coil needs to be cleaned.