Dometic AC 13.5K fan failure.

[StanZZZ]

2005 Mobile Suites fifth wheel 36 ft with typical Dometic set up. Zone 1 Living area has 15K A/C with HP. Zone 2 is Bedroom with 13.5K Air conditioner only. Both are OE, Furnace is 42K all hooked together with a 5 button CCC thermostat.

Zone 1 works perfect. Furnace works almost perfect.

Zone 2 will run for ever on Fan only low or high

Zone 2 will run forever on Air conditioner on Fan low or on Automatic if difference between set temp and room temp is small enough to keep fan on low.

On Fan high or Auto with wide spread in temp the fan will start, the compressor will kick in and the unit will cool and run normally FOR NINE MINUTES. Then the fan will lock and the compressor will hummm. I don't know how long it will hummm as I always turn stat to zone 2 off before it pops a breaker.

Both capacitors check OK on my tester. I replaced my fan motor after I found some black windings and some burnt paper in it. That did not help and is a job I probably won't do again. I have two stats. One is a spare and it does it with either. I've checked all wiring and connections but it seems that if it was a bad connection it wouldn't start and run for nine minutes. I'm running only the one air conditioner and nothing else on my 30 amp home RV pad, but the problem started last winter in Florida on a robust 50 amp site.

I suspect the control board. I replaced it a couple years ago when the same air conditioner was running on it's own and not stopping until I pulled the circuit breaker. The board fixed the problem but there is one more small clue that puzzles me. When I installed the new board HEAT PUMP came up as a setting on the zone 2 tstat. It has no HP and never has and according to my Dometic manual no setting will be on the tstat that is not available.

Could they have given me the wrong board? Pretty sure I would have examined them pretty closely but I am 75 so you never know.

I have ruled out a compressor problem because it stays on when the fan shuts down. I have searched on all the on line forums I can find including 28 pages of posts by Doug. I not only can't find a solution I can't find anyone reporting the same problem.

I am open for suggestions.

[dougrainer]

1. The CCC2 board on the AC looks nothing like the 5 button CCC board you had originally. The board quick connects do not line up and plug in correctly also. NEW CCC2 boards have 3 fan speeds The OLD CCC 5 button board only had 2 fan speeds. The CCC 5 button the MED fan speed not used was used to energize the HP solenoid.
2. You need to verify that the OLD original Board looks exactely like the new board.
3. IF you buy a Penguin Roof AC/HP, and you have the OLD CCC 5 button, you MUST purchase a 10 button to 5 button Board kit and rewire the AC/HP to fit the new AC wiring.
4. IF you have verified that you do NOT have the HP DIP ON and it is OFF and you have HP displayed, then you probably have the wrong Upper board. Doug

[imgoin4it]

My problem I explained above sounds very similar to yours. My acnd would run-initially for about 18 minutes and then the fan would shut off but compressor would hum. After leaving it on it would run for 3 minutes, fun shut off, and hum continue. The fan would come on 4 minutes or so later for another 3 minutes. What caused it was connecting the wire to the board rather than clipping it off as I explained. What was happening was the fan motor was cutting off due to thermal overload. The motor was shutting off because it got too hot. In fact hot enough to burn the techs hand when he touched it. The fan motor and the board was not capatable because it was a three speed motor, high, medium and low. The thermostat would only work correctly with a two speed motor. Cutting the wire of disabled the medium speed leaving only low and high. Problem solved

[ScottG]

I would replace the capacitor - it looks like it's breaking down internally.
A cap will measure fine until it shorts and can even be temperature sensitive.

After about ten to 15 years it's a good idea to replace them as a maint. item just like residential customers are suggested to do.

[StanZZZ]

UPDATE UPDATE new info. I appear to have an excessive amp draw with the zone 2 air conditioner. 120 volts to RV, nothing else running. Zone 1 AC pulls around 16 amps starting and runs at 12 to 13 amps. Zone 2 pulls like 22 amps starting and runs at 18 to 19 on air conditioner low fan. On air conditioner high fan it pulls 25 or 26 starting and runs at 22 to 23.

It is not tripping circuit breaker but I'm thinking the high amp pull is causing the fan motor to shut down. Question is why the fan motor and not the compressor? I cleaned everything when I put the new motor in. I guess I'll look next for some loose connections but I'm thinking it's a compressor problem.

[imgoin4it]

Had similar problem after installing new replacement acnd / heat pump.long story short . After 1st extremely well qualified tech installed unit it would not work. Was checked by 2nd extremely well qualified tech who after 4 hours of working could find no problem. Finally called Dometic tech service and found that because of changes in units the board required to make a new unit work with old thermostat one wire somewhere had to be cut off rather than connected to the board as instruction indicated. Both tech said there are so many changes Dometic could not change instructions as fast as they made changes to units. I had called Dometic customer said I need to have a tech call them. In fact insisted on it. They were correct about that

[StanZZZ]

Dip switches checked and are in the right place. I may pull the board and toggle the HP dip back and forth just to see if that corrects the error.

Big Katuna. Did you change those out yourself? Did you stay with dometic?

[Mandalay_Parr]

Check all the dip switch
and Jumper
settings on the board.

[Big_Katuna]

I have a 2005 Fleetwood with Dual acs.

I replaced the front last summer and just replaced the rear last week.

I wouldn’t put too much time or money in them.