[BigBoy2U]

OK this is a tad long but…just want to run this by you guys. What I am thinking of doing. So I am looking to see if anyone else has done this.

I just bought a used 05 36CK3 everything worked when I left the lot (figures) but we recently have had some cold (25 degree) weather in Seattle. I haven’t been able to move into the unit just yet. But the other day the furnace worked fine, it worked fine the day I picked it up. It was a repo so I knew anything that went wrong I was going to fix. The dealer would fix anything that didn’t work at time of inspection. So yes I did steal it for $40,500 and its in great shape just no furniture and need a good cleaning!

So I go to fire up the furnace one night since the unit is not winterized and nothing. I play around with the 5 button climate system, go online and get the instructions and still no go. Now I mean no fan, no cycling dead. (Ok this is where I know about propane levels, etc. But this is a NO power, no fan, no cycle, no try to start…nada, zip nothing.) Checked the fuses all OK. So off to read more than I ever wanted to know about the Duo-Therm Climate Control 5 button system. My system is set with 2 zones for AC and one zone for furnace. No heat strips and no heat pump. I tried the power down, switch the thermostat on and off, did the reset many times and still get FF. So I know its reading the CPU at the rear AC.

I am about to probe down to the furnace when I tug on the wires and sparks. I look and the wires are chafed where they leave the side of the furnace and the “On-Off” switch for the furnace is loose hanging there not attached to anything. The next day I pull the cover off the furnace to find (1. the trim ring is not even siliconed or sealed in any manor to the body, 2. the screws are all mismatched and half are lose and stripped. Now it doesn’t look like this has ever been out since the paint lines match up.) I just can’t believe DT didn’t even seal the plastic trim piece. So I also notice the plywood they filled between the fiberglass and the frame was wet from water running down the side of the exterior and then into the opening that was not sealed. (Anyone else have this problem?) You should all check your furnace trim ring and see if it’s sealed to the body. At least caulk it in place if its not.

Ok so I look at the wires along with all the mouse droppings and realize what happened. Mr. Mouse was living in the furnace and stripped half the wires. So I cut, replace and heat shrink tube the bad wires. Reposition the on-off switch and still furnace wont fire off. VOM the power, power ok, ground is good so next jump the thermostat wires and it fires off (well ok it was out of the unit but the blower motor run until it timed out.)

I have pretty much at this point come to two conclusions, 1. The thermostat is bad or 2. The control module up in the rear AC unit is bad for the furnace output and got fried with the wires shorted to ground. I am able to get the fans to run on all 3 speeds + auto on both zones (cant get the AC to kick on since its still in the 30-40’s here). So I have to guess that the module will work the AC (fingers crossed). Now I admit I have not taken the roof AC unit cover off and checked the wires. Could be no 12V at one of the furnace wires or a bad connection also. But it got me thinking...about doing this instead...

Ok so here is what I want to do: Install a separate thermostat for the furnace. At least I can get one that is programmable to turn down the heat and back up again a 7 day 4 program thermostat for $29 at Lowes. (I did the Hunter replacement on my Avion and this is a simple two wire compared to that install…lol)

Anyone see any reason why not to do this? I don’t see it being that much different than having to switch the “modes” on the 5 button to furnace. Just need to make sure the old 5 button AC is not set to run when the heat is on and make sure the furnace is off to run the AC in the summer. To me is really makes it a lot easier to have a complete system this way. Set AC to not come on until 77+/- and never set the heat above 73+/-. Two separate systems that can work as one. Set it and forget it and just leave them both on as programmed.

At some point I will get on the roof and set the dipswitches to remove the furnace from the 5-button program. So it won’t confuse anyone else and just label the thermostats properly.

OK fire away!