Thermostat Problem

[mdebs]

I have a 2016 Coachman Mirada MH and am getting ready to leave the cold and head south. I brought the MH home today to pack and can not get the thermostats to operate. I have two dometic single zone LCD thermostats and neither will turn on. I checked all of the DC fuses in the panel and they are all good. I also checked the AC circuit breakers and they are all good. I can't find any other electrical probelms. Does anyone have any suggestions on what could be causing this.

[ejohnson1144]

Is battery disconnect turned on

[mdebs]

Yes

[MtBiker]

They may have an internal battery.

[mdebs]

I can't fin one and don't know where it could be located.

[Thurman]

Some Dometic A/C units have a transformer to supply the Dometic LCD t'stat's even for the furnace mode. Make sure your A/C unit(s) have power to them. Mine are this way.

[mdebs]

I had a bad ground wire to the air conditioner controller. When I added a new ground, the thermostat was fine.

[rockfordroo]

Thanks for letting us know. It will help the next guy.

[mdebs]

A little more detail. I used a multi meter to check the voltage going into the thermostat. It was zero. I then pulled the cover off the air conditioner and checked the voltage going into it on the 4 prong plug. It was only 4 volts. I checked the voltage using the hot wire on the plug (red) and using the plate the holds the air conditioner controller in place and it was 14 volts. This meant the ground was bad somewhere. I added a new ground wire to the connector that held the ground wire (black) to the air conditioner controller and connected it to the screw that holds the controller in place. Hope this helps someone else.