A/C ghosts??

[BamaUltra]

Have a 2003 36' Gulfstream Ultra Supreme. Never had issues with A/C's b4 & don't know anything about them? I do have an issue with the front unit now.Unit works as intended when controlled by thermostat. But, when Off @ thermostat & plugging up 2 shoreline; 50 amp service; &/or running power with 5500 On an generator, as soon as u plug in or generator is initiated..... the front unit Air comes on; thermostat OFF;sounds if it trying to come ON?? Trying, because it's only running w/NO air coming out??? As soon as power to Coach, it runs 4 2 to 3 mins. and off for 20 min then cycles like that throughout having power source?? I checked Converter, it was fine, but upgraded to another that has 3 step charging instead of single phase. I'm cautious of covering back up with this problem. Could u help??

[BamaUltra]

Would like to take a few min. To reach to Chris Bryant & Doug Rainier & let them BOTH know how much I appreciate All the positive, patient advice that they shared with me on my troubled A/C... I recieved the Control Board today, put it on & fixed the problem. The se guys were Very knowledgable with my particular situation & was fixed the First time... Not to mention Hiw much $$$ they saved me from NOT having to take it in to a Shop? Thanks again guys also to RV Open Roads Forum.

[BamaUltra]

Doug, 1st of all thanks for all ur input. I can tell ur very knowledgeable & I appreciate everything offered. Just hate it I'm NOT @ A/C.I believe u have it narrowed down for me. When I initiated power to the Coach & go inside the A/C is already running;but NO fan;I noticed the thermostat fan was on auto.When I turned on the fan, it blower cold til I took off & put back on auto and fan stopped with a.c. still running. At this time I unplugged & I believe ur right about Board. Gonna order one tomorrow. What do u think? Thanks4 ur patience

[BamaUltra]

Thanks Doug. My concerns is when I plug in to shoreline or crank up generator; with thermostat bin OFF position; as soon as I do either, the front a/c unit comes on; but NO air blowing? But, I can go in & turn unit ON & adjust temp necessary to get a/c to come on & it operates normally & I can adjust accordingly and it shuts off & on just fine? But why it cycles through in the OFF position; 2 min. ON & 25 min. OFF; as long as it's in OFF position & got power to Coach?

[dougrainer]

There is a Compressor and there is a FAN. Now, When the FAN shuts off from the tstat, the compressor should stay ON if the relay is defective. If both the FAN and Compressor shut OFF when the tstat temp is reached, you relay is working. One thing you can do, is swap the front and rear control boards. If the problem follows the control board you have a defective control board. Are you POSITIVE that when operated by the tstat and the system shuts OFF, that the compressor does not come on in the next 10 to 20 minutes by itself? Doug

[BamaUltra]

One other thing Chris, if the relay is welded close; shouldn't my AC NOT Work when I control it with thermostat? Cause I can turn it on @ thermostat and set temperature & it cuts On & OFF perfectly? Looks like, to me, it would have same results of relay on board was bad and wouldn't blow air? Just saying, I don't know anything about these things. I appreciate all ur advice. Thanks

[BamaUltra]

Thanks so much 4 Ur advice Chris. My Coach being '03, will the board I order from eBay work on a 16 yr. Old control board? U seem very knowledgeable about this? Thanks to y'all again

[Chris_Bryant]

BamaUltra wrote:
The a/c works great with either power source? The problem is when unit is in the OFF position and you plug in or crank Genny, the front unit, ONLY; tries to come on for 2 mins. and cycles that way; with NO air coming from vent; off for 20 mins. & Does those cycles as long as power is coming to it? No matter which source? I can go in & operate with thermostat ON & control thru temps & works just fine with air coming from vents & all?

Not sure why every sentence is a question, but I stand by my last post- your upper circuit board has a bad compressor relay and needs to be replaced, from the symptoms you have given.
.??

[dougrainer]

AS Chris told you, the Compressor relay is fused closed. The Compressor is coming ON and because NO FAN is running, the compressor is overloading and the Overload switch kicks it out. When it cools down, it comes back on. You need a new upper control board. The compressor relay is not a separate part. Doug

[BamaUltra]

The a/c works great with either power source? The problem is when unit is in the OFF position and you plug in or crank Genny, the front unit, ONLY; tries to come on for 2 mins. and cycles that way; with NO air coming from vent; off for 20 mins. & Does those cycles as long as power is coming to it? No matter which source? I can go in & operate with thermostat ON & control thru temps & works just fine with air coming from vents & all?

[crawford]

It sounds like your are saying when Genny is ingaged you have a problem if you check you circuit breakers on Gennys itself one my be tripped.

[Chris_Bryant]

Sounds like the compressor relay is welded closed on the upper circuit board. You should shut the breaker to it, as it will run the compressor and cycle on the overload as it overheats.

[enblethen]

I would verify that the power to the rig is correct.
Test the system to insure the neutral is in good shape.
One of the small three light tester may aid in this test.
best way is to use a volt meter. test at the 120/240 volt distribution panel.
First item that could be issue is the neutral relay in the transfer sitch.