AC and Heat Suddenly Stopped Working

[us71na]

Originally Posted by newbold1

Oh... the digital display is dead except when I put batteries into the thermostat. I haven't figured out for sure whether the thermostat should power up without batteries if the 12 volt power was coming in through the wiring. I really don't know as I have always had batteries installed and never really tried it without them to see if the wiring itself would have done the job to power up the digital display.

If your thermostat has batteries, then it only functions as an on/off switch and the batteries must be installed for it to do anything. There is a set of contacts inside that open and close to send your 12 volt power to the device being operated. The batteries operate the thermostat to tell it when to ope or close the contacts according to the set point.

[Sunflake]

Does everyone’s furnace cycle the burners but keeps the fan running?

[Lowblues]

Just wanted to say that this little bit of info was correct for my 2016 Eagle 5th wheel. Hard to get to the gas heater but once I did, it fixed the problem. Thanks!

[Jon65254]

I was so excited to come across this ride after two days of searching. This is the exact problem that we're having and I was so happy to hear it was a simple solution like that button. I did find the button however it did not fix our problem. Still the same exact problem AC and heater are completely unresponsive. We have no line fuse, no fuse or breaker is blown but it doesn't seem to be getting any power to the heater.

I would have been so upset if I paid a repair person to come out here on all they had to do was flip a button but unfortunately that didn't solve our problem, any other suggestions?

[BackyardMechanic]

My ac and heat also not working. Found that thermal breaker mounted to furnace also supplies 12 volts to thermostat. Mine was only sending 2-3 volts on the load side of the switch to the thermostat. That explained why neither system was working. I replaced the breaker/ switch and every worked again for one week. Again I only had a few volts coming from the thermal switch. I assume they’re cheap junk and I will now eliminate. I’m going to bypass and add a non fused switch ahead of the furnace. From there I will add a fuse-able link to the furnace with a slow blow 10-amp fuse. I will also add another fuseable link for the thermostat power but use a fast acting 10-amp since this is only for control wiring.