I think the AC is no good now

**concreteman** · 06-17-2016, 11:16 AM

Well I have figured out a couple of things. I have the plenum sealed so I know that I dont have cold air mixing on the intake side. But when I press and hold the sleep button the temp shown on the thermostat is about 8 to 10 degrees less than the actual temperture inside the coach mesured with a thermometer sitting on the kitchen island. I have found if I set the thermostat 8 to 10 degrees cooler than I really want it every thing works fine. Say you want it to be 74 in the coach set thermostat at 64. Then I have no more short cycling of the compressor. Fan runs on high, when the compresor shuts off fan goes to med then to low. Look at the thermometer on the kitchen island 74. Go hold the sleep button in and it says 64.

Im not sure if I have a bad temperture sensor or what ? When I was sealing the plenum I could see the sensor clipped to the fins on the intake side. Not sure whats going on but that is the solution I have come up with for now.

**TucsonJim** · 06-17-2016, 02:47 PM

That sounds like a good way to deal with it. Probably just an inaccurate sensor.

Jim

**JustinThyme** · 06-17-2016, 08:47 PM

I'm going to have to open mine up to look now. The sensor should not be directly on the fins of the evaporator. It will never work correctly that way. Tstat is supposed to measure return air temp, not the coils. That explains not getting cold, measuring lower than ambient and compressor short cycling. If it's a few inches in front of the coils it should work OK but right on them the coils are going to drop to 15f. Below ambient less than a minute after the compressor starts.

**concreteman** · 06-20-2016, 08:31 PM

Rob, did you look at yours? It is clipped on at a angle so the sensor is about a half inch from the fins.

**JustinThyme** · 06-21-2016, 01:39 PM

Haven't had the opportunity to yet. My rig is parked on a seasonal site about an hour away. I'll be down there this weekend.
1/2 inch sounds awfully close and make me wonder if the mounted offers some thermal conduction from the evaporator coils. I was looking earlier and there are 4 temps sensors in this system. Outside temp, outside coil, inside coil and return air temp.

Curious if you just have the fan running and hold down the sleep button of what you get and is that still 10 degrees off. If it isn't off unless the Compressor is running this would suggest that either the sensor is picking up too much from the evaporator or possibly the sensors are crossed and what the Tstat is displaying in the temp from the coil sensor.