Help with AC/Furnace circuit.

[Jim Godward]

Ok, here is the problem, during a recent storm, the rear AC shroud was blown off during the night.  I had a need for something in the MH and braved the storm to get it.  The front AC fan was running, not sure of the compressor but I don't think so.  The thermostat switch was in the off position, no display on Thermostat when I turned on, the rear AC was not running, either fan nor compressor.  I tuned off the 120v power to both ACs, and removed the 12v fuse, got what I needed and dash into the house.  NO additional storm during the few days it took to get a new shroud.

How can I disable the rear AC to get power back on the thermostat and furnace till I get down south and have time to fix it properly.

Also where can I get the layout for the foam strips that go in the shroud to separate the portions of the AC as needed.  It is a Dometic Penguin AC.

And yes the shroud was old but I haven't been able to get on the roof since QZ 2010. 

I hope I have provided enough information so that one of my neighbors can do the work for me based on the answers I get.

TIA,

 

[Ned]

Can't you just leave the breaker for the rear A/C off?

 

[weewun]

On my Diplomat the Tstat receives power via a Telephone type Cord and Connector from the front AC (Master).  The rear AC receives its control signals via another Telephone type cord from the front AC.  Either AC can be the Master depending how you run the TT Cords and set the DIM switches.  The Master AC will have two TT cords plugged into it.

In your opening paragraph you said your front AC's fan was running and that the Tstat was off, was that at two different times???

If turning off the Breaker does not isolate the rear AC, you might try disconnecting the TT Cord going to the rear AC.  I don't remember a DC fuse on the AC Control Board and am not close to my documentation.

 

[Jim Godward]

In answer to Ned, no with the rear AC breaker off nothing changes, no power to thermostat and front AC fan runs.

Walt, I suspect that disconnecting the rear data communications cable and the rear AC power off will partially and maybe resolve the immediate issue.  I hope to get that done today if my neighbor is available.

I see a fuse in the 12 volt line at the AC so need to resolve that.  I have conflicting information in Dometic documentation.

 

[Ned]

Then your rear A/C is the master unit.  Can you disconnect the power from the control board to the motors?  That would leave the thermostat powered up for the front A/C to operate and keep the rear fan and compressor from running.

 

[Jim Godward]

Ned,

I think the front is master as it is mode 1 and rear is mode 2 which is what the Dometic documentation indicates.  I think the problem is somewhere in the 12 volt control circuitry, likely in the rear AC.  Hopefully disconnecting the data communications cable will partially resolve the issue and allow the furnace to operate.  I won't need AC for quite a while even in AZ/CA this winter.

 

[Ned]

Ok, I guess the only option left is to disconnect the data cable and see what happens.