Need AC help!

[SkyBound]

Out camping now, friends trailer air conditioner isn't working and it's getting hot!

Ducted Coleman Mach 3 on a 26BH, slide thermostat control to Fan and the fan won't come on. There is an audible click inside the unit like a relay but the fan will not come on when set to Fan or Cool. Apparently it worked last night but not today. The fan spins freely by hand. When set to Cool it sounds like the A/C is working (sounds like a fridge) but no fan to blow air.

Any troubleshooting suggestions?

[Grumpy]

On both high and low? Sounds like a bad motor.

[SkyBound]

Yes both high and low it won't run. The fans and shaft spin freely but the motor won't turn them. It sounds like there is a buzzing sound coming from somewhere in the unit when switched to Cool but I'm not sure what it is.

[RedHorse1]

Yup, bad motor most likely. Possible a problem with the capacitor but my $$ would be on the motor (when replacing I'd replace the capacitor too).
I replaced one of mine this past fall, not a difficult DIY and was about $120 from
Amazon IIRC.
Good luck!

[mike837go]

Also check for blown breaker. The IIRC the control system is 12VDC. If the RV is unplugged or the pole breaker tripped, the A/C won't work, but everything else does!

[turbo130]

My brothers a/c had the same problem there was a glass type fuse behind the thermostat cover that he replaced and a/c works fine now. You might try that.

[SkyBound]

I figure I owe you all fine people an update on this. All great suggestions, and I thank you for answering my call for help.

I would like to point out the importance of correct polarity when hooking up your battery. After a day of troubleshooting and confusion, it finally came out that the owner of this trailer had previously incorrectly hooked up the battery (but only for a minute lol).

After the overhead blower fan wouldn't work, eventually the water pump, lights, fridge, and anything else 12V stopped working. The compressor would come on when Cool was selected, but no blower fan. The 2 40A fuses in the converter (reverse polarity protection) were blown. I can only hypothesize that the improper battery hook up maybe just damaged the fuses initially, and then on this first trip of the season pulling the 12V current through them finally cooked them? Anyways, I didn't have 40A spares so I used two 30A fuses (my personal converter has 30s in it from the factory anyways) and everything came back to life, including the air conditioner fan.

The only thing that didn't come back was the radio/DVD which required its own 10A fuse in behind to be replaced.

All is well now, and although I don't fully understand how this all happened I'm happy it was a cheap fix we could do ourselves. I know the thermostat is 12V so maybe that was the link between blown 12V fuses and an 120V appliance not working.

Moral of story: Hook up battery correctly, check ALL fuses and breakers as a first step for something not working.

[Grumpy]

Glad you got it working, but that theory is not valid.

The same 12v control voltage (single 12v wire to the thermostat) controls both compressor relay and fan relay in the a/c control box. Had to be some other issue.

[TWP723]

Originally Posted by SkyBound

Moral of story: Hook up battery correctly, check ALL fuses and breakers as a first step for something not working.

Great advice!

[SkyBound]

I think the fan relay was working since I could hear a click in the overhead unit when switched to Fan mode, but the fan wouldn't come on.