Dometic heat-pumps, with 5-button Controller

ronboc · 07-31-2007, 04:15 AM

I've had this happen the past 4-nites straight...

When we go to bed at nite, I set the rear-AC on 57* cool with fan on high (we like to sleep cold). Sometime during the nite, the fan will go to low-speed all by itself. If I get up and cycle the SPEED switch thru its settings several times, it will most likely go back to high-speed, but then will drop back to low again sometime later in the night (And I get to do it all over again). It is NOT in the auto-fan position, and the compressor sounds like it's working normally. The front unit has never done this.

Any ideas?

TIA,
Ron

ronboc · 07-31-2007, 04:15 AM

I've had this happen the past 4-nites straight...

When we go to bed at nite, I set the rear-AC on 57* cool with fan on high (we like to sleep cold). Sometime during the nite, the fan will go to low-speed all by itself. If I get up and cycle the SPEED switch thru its settings several times, it will most likely go back to high-speed, but then will drop back to low again sometime later in the night (And I get to do it all over again). It is NOT in the auto-fan position, and the compressor sounds like it's working normally. The front unit has never done this.

Any ideas?

TIA,
Ron

**RV Wizard** · 07-31-2007, 11:54 PM

Ron, when this has occured did you take noice if the evaporator coil was frosted over? Look next time to see. It may be a default setting in the control board. If you will provide me with the model & production #'s I will see if I can get a better understanding in the service maual.

ronboc · 08-01-2007, 04:28 AM

Hi Mike -

Thanks for the reply.

I'd thought of it freezing-up, but we're in Denver with <20% humidity so I discounted it. I'll take a look when it does it again, based on your thought (gonna have to wake the boss, though). I did reset the controller last nite, thinking maybe it got confused once in a while. Nope, same thing.

AC is a Dometic 630035.321, I hope that's the right number.

Thanks in advance!
Ron

**RV Wizard** · 08-02-2007, 12:00 AM

Ron, I have downloaded the service manual but have not had a chance to look up the possible cause of your problem yet. I have not forgotten about you and I will try to get some time to do this today. Will get back to you soon.

**RV Wizard** · 08-02-2007, 02:13 AM

Ron if you have the Comfort Control Center thermostat and it is controlling both thermostats, I think you may have a bad thermostat. There two ways to verify this, one is to replace the thermostat; the other is to check the control voltages on the board coming from the thermostat. I do not see any other probable causes from the service manual. One thing you could try would be to use some electrical contact cleaner on the thermostat board. Be sure to use one that is safe for plastics.

ronboc · 08-02-2007, 04:57 PM

Hi Mike -

Thanks for checking on this for me.

Yes, I have the single controller for both AC's. Is the manual a service-personnel-only product or is it available to us 'unwashed' masses? You mentioned checking the voltages, what and where?

Is it possible to swap the AC control wiring to the units to see if the problem follows? I can't seem to get your comment out of my head that it 'may' be freezing-up a bit and just doing what's normal.

Many thanks!
Ron

**RV Wizard** · 08-02-2007, 11:44 PM

Ron if you will send me a private message (just click on my user name) and invite me to a PM and send me your email address. I will see if I can send you the service manual in a pdf file. You can check the voltage at the control board on the roof unit once you get the service manual it will make more sense.

Ray,IN · 08-06-2007, 06:34 PM

You may download either the specific service manual or the complete service manual covering all Dometic A/C, and heat pump units from Bryant RV.
The link is also in the sticky RV Wizard created at the top of this forum.