AC Thermostat Quit

[Two_Hands]

I have an RV comfort.zc thermostat in my coach (described below). It controls the front and rear air conditioners and the front and rear furnaces. Zone 2 is for the rear and it works properly. The thermostat will not change to zone 1 so I can't operate the front ac or furnace. I repeatedly press the zone button, but it stays on zone 2. I've done a search, but can't find anything. Can anyone offer any suggestions? Thanks in advance.

[dougrainer]

Two Hands wrote:
Tinstar I thank you! I turned off the batteries, waited awhile and when I turned them back on the thermostat worked properly. I hope it is not just a temporary fix. Thanks everyone for taking time to read my post and reply.

The power down fix is usually for when the ZC control shows OO on the display. Never heard of it failing for just 1 zone not showing up and rebooting the power restored it. Doug

[Two_Hands]

Tinstar I thank you! I turned off the batteries, waited awhile and when I turned them back on the thermostat worked properly. I hope it is not just a temporary fix. Thanks everyone for taking time to read my post and reply.

[dougrainer]

OK, on the newer ZC tstats, they use a twisted stranded wire to prevent RF or AC Ripple interference. You can rule out this by having EVERYTHING OFF in the RV and then trying the Tstat. IF you have NO Zone 1 indicated and you had Zone 1 before. You need to go to the front Zone 1 AC and access the Control PC module. Open the cover and you should see a solid or flashing Green LED light. IF NOT, then there is no 12 volt power to that Zone 1 module board. You then need to verify 12 volt power to the module. IF no 12 volts on the 12 volt input, your problem is downstream either at the fuse block or possibly the Front Furnace. Some RV's use the Furnace power for the Power to the AC that is controlled at that Zone. It is uploaded by the 2 Furnace tstat wires from the furnace. One wire is 12 volts and the other is the return 12 volts when furnace heat is called for. Doug

[doc_brown]

My thermostat acted up and after some experimenting I determined it was a faulty ceiling light ballast. Removed them all and went to direct wired led's.

[crasster]

Have you looked on the front of each furnace for a furnace control board? It may be more involved than a thermostat. Sometimes control boards go bad.

[dturm]

Just had the same thing happen. After troubleshooting, pulling fuses and trying the reset, I found the problem was the cell phone signal booster. As soon as I turned it off, the thermostat worked perfectly. Look for a source of RF interference.

Doug

[Tinstar]

For a temporary fix, I understand you can turn off the house batteries for about 5 minutes and that will reset the thermostat. I've also read you can pull the fuse in the thermostat and leave it unplugged for 5 minutes to do the same thing.

If you search the internet for RV comfort zc thermostat, you'll probably find several post about this procedure and what causes the problem. Several sites says it's an electronic interference that can be caused by fluorescent light ballast, phone chargers, vent fans, etc. They say to put in a choke filter.