Furnace run with AC on.

[Feldhege]

Ok what did I do? Had a tough day at work so I decided to tackle my next mod. I installed my progressive industries 30 amp hardwire kit with remote display. Everything seems to have went well. However now, when I turn on the AC the Furnace also turns on and blows heat?! I don't think I screwed anything up. I had the shore power off and the battery disconnect turned off. Everything else in the camper seems fine. Please someone give me an idea of why this would happen before the DW gets home.

[Dave_Monica]

Check to see if your fan selection is in the 'On' position instead of 'Auto'.

Dave

[Feldhege]

Nope. This is what the thermo looks like. Of course before I turn the switch to cool.

[Feldhege]

I also tried pulling the fuse for three minutes to see if it just needed to be reset. Saw that in another thread about a furnace not turning on.

Last bit of useful info is I tried to turn the furnace on by itself and the AC did not turn on. This is weird.

[Dave_Monica]

I can't imagine that installing the surge protector would have any bearing on your problem...it's got to be in the thermostat control wiring.

Dave

[Feldhege]

Is that anywhere near the power supply for the camper? Maybe knocked a wire loose? Or shorted out? I don't see anything.

I really wanted to go camping this weekend.

[Dave_Monica]

Have you tried to operate the AC fan in manual 'On'?

Dave

[Dave_Monica]

Also I'd pop off the thermostat cover and look for loose wires or connections.

Dave

[VinceU]

Originally Posted by Feldhege

Is that anywhere near the power supply for the camper? Maybe knocked a wire loose? Or shorted out? I don't see anything.

I really wanted to go camping this weekend.

Sounds like the heater lead an the a/c lead have shorted togrther in the thermostst control unit or in the leads leading to the thermostat. Meatime pull the fuse on the one you don't want.

[Feldhege]

Well the furnace and refrigerator are on the same fuse according to the panel. That won't work.

So I tested it and the furnace will run fine on its own. If I just turn the fan on, the AC blower will work fine. Turn it to cool and the furnace kicks on seconds after the cooling begins.

The wires look fine on the thermostat and the power center. Also the thermostat is on the left of the camper with the furnace below it. The AC is on the roof of course. The power center in on the right side of the camper and I mounted the surge box behind it. I may have to see if I can take it to the dealer.

[Feldhege]

Called the dealer and he is booked until the 20th. He said that he can't think of any reason why what I did would have caused the issue. He thinks it was just bad timing. It made me feel better anyway. He also could not think of a reason that it would be doing that. In the meantime, he told me to open the furnace compartment and disconnect the white molex plug from the board. That will disconnect the furnace but the AC should still run for now. We leave for the 4th of July camping on Thursday. Should not need the heat.

[Feldhege]

So I decided to do a little more digging. I opened the thermostat which looked fine. Nothing is burnt inside. I disconnected the white furnace wire and tried the air. Everything works fine. At this point I am guessing that it is the thermostat that maybe went bad. Picked up a new one on my way into work ($50) and will wire it up tonight. I can return it if this doesn't fix it because it is an electrical part but it is worth the gamble to me because I can replace it myself versus the shop labor rate of $75 per hour. I will let everyone know how it goes.

[VinceU]

Originally Posted by VinceU

Sounds like the heater lead an the a/c lead have shorted togrther in the thermostst control unit or in the leads leading to the thermostat. Meatime pull the fuse on the one you don't want.

So go campin this weekend ; )

[Feldhege]

Yep. The new thermostat fixed the issue. Old one looks perfect but it still works wrong. Guess some logic circuit may be burnt internally. Thanks to all for help. Have a great 4th.