Have Class A with basement model duotherm with 2 zones, had been working fine till plugged up at campground with low voltage. Now only one zone will show and operate.
Have replaced wall thermostat but still no second zone will show up or operate.Local vendors not helpful on repair, seems no one in area knows how to diagnose a dual zone unit.

Any suggestions?


Senior Member

While I hate to bear bad news, the fact is that under voltage will cause an AC motor to draw excessive power and thus to get hot. If you are lucky, it will open the over temperature device in the motor and in time will get well, or can be reset. But in extream cases, the motor will be destroyed.

I have no knowledge of the basement type of air conditioning, so let's hope that it isn't what I think of!

Gary B

Senior Member

Hi budzo, welcome to the forum, you need to provide more information, are you asking about a furnace or air conditioner? What kind of a MH is it make model year of mfg.? I suppect you are talking about air conditioning, and that the coach is splite in two areas, like bedroom and front room, and my guess is that the zones are controlled by a circuit board somewhere in the coach and that the low voltage may have damaged one of the circuit boards. :) :laugh: :cool: :bleh: ;) :approve:

sorry about inadequate info,
1986 Holiday Endover with DuoTherm split system basemant model. Thermostat is locarted in dining area on wall which would show the 2 seperate zones ie: [Zone1 or Zone2] till this occured, now it will not show a specific zone. Rear zone still works normal however the front zone seems dead.

I would tend to agree with Gary, the control system is probably messed up.
Contact Duotherm directly because you need to find someone who is familiar with this unit's control system to troubleshoot it. Some systems have built-in protection for low-voltage situations and some just fry. Some protections need to be manually reset by someone who knows the ins and outs of the system.
If you can't find a service center locally, some HVAC contractors may be willing to look at it if you can get a service manual. Residential A/C systems use multi zone control systems that may be similar.

After you correct your problem, I strongly suggest you get yourself a Surge Guard. They are less than $400. I installed one in '99 and it has saved me thousands because of lousy campground voltage and lighting strikes. It drops your coach out on both high and low voltages and auto resets when problem is passed and saves your electronic systems. :laugh:

The last time my Duo-therm suddenly "did nothing" it was merely a blown fuse in the unit. I took the plastic cover off, took the galvanized cover off and changed the car style fuse. I don't believe that Low voltage could blow a fuse. However, if your Duo-Therm suddenly doesn't do anything check this little $1 fuse before calling in the big guns.