norwestie Report post Posted May 29, 2017 Last week was the first trip of the season where I had the A/C on. The outside temp was 70ºF and 30% humidity but after a while it got up to 80ºF inside. So I turned on the front unit. It cooled for several hours, running normally, then just stopped. I checked the breaker panel, nothing tripped. I checked the 50 amp on the pedestal. No problem there. Both the front and rear thermostats displays were out, nothing showed. After about an hour, the displays reappeared and the air conditioner worked. What would cause this? 2000 Monaco Dynasty Share this post Link to post Share on other sites
obedb Report post Posted May 29, 2017 Thermostats are powered by 12 volts. Voltage disappearing and coming back on it's on while you are in a park is confusing. Running down the road with that happening would suggest a faulty connection. Did you have 12 volts for the other appliances? If not maybe the "salesman's switch" circuit is involved. On our coach that switch is located on a small panel in the step well. My guess is that switch controls a relay that supplies 12 volt power through out the RV. Intermittent electrical problems are a pain. The switch might be the problem or the relay could be the cause. Just a guess. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 29, 2017 The next time it does this try this. turn the thermostat off now pull the front off the thermostat. Inside is a fuse. Remove the fuse (it wouldn't hurt to clean the contact surfaces) after a couple of minutes reinstall the fuse and see if that helps. If that doesn't help I would look at the 12V power supply. Bill Share this post Link to post Share on other sites
norwestie Report post Posted May 29, 2017 The confusing part of this is 1) that both thermostats' displays disappeared (even though only one was powered up) and 2) that the power to both was restored without any intervention on my part. Share this post Link to post Share on other sites
obedb Report post Posted May 29, 2017 If the thermostats have 12 volts, the display works even if the switch is in the off position. If you lose power to the thermostats, check other 12 volt powered equipment. Interior lighting, absorption type refrigerator, water heater, pump etc. If they also do not work, it has to be a common problem. Something is amiss in the 12 volt supply circuitry. Share this post Link to post Share on other sites
