Phantom furnace problems

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
H

hockeycoach15

Active member
Joined
Jun 5, 2012
Posts
25
Another NASCAR race, another problem ::). My problem is the furnace coming on without it being switched on. Got home last night late, went out this morning to empty and clean the rig, and the front furnace was running. Opened the entry door and it had to be at least 90 in the coach. The controls were all in the off position, and the thermostat was at 60, for running the A/C over the weekend. Took the panel off, just 4 wires and a sealed unit. so nothing obvious. Any thoughts or help will be greatly appreciated.
 
George, if your 2000 PA is like our same vintage Bounder, we have an intellitec thermostat that looks like the pic. below. I have more than once turned both switches to the full up position thinking they were both off, then realized the left one had to be down one. If this is not the issue, there should be two control wires from the furnace (blue I think) that the stat switches together to start the furnace. The other two wires in the furnace are hot 12volt and ground. Perhaps the control wires have been chaffed somewhere or the t-stat is bad.
 

Attachments

  • T-Statrs.jpg
    T-Statrs.jpg
    39.9 KB · Views: 39
Dennis is right on.

The switches may not have been on, but this problem has been reported many times (do a few Google searches) and most have been traced to a faulty T-stat or T-stat wiring.  Moisture condensation in the T-stat or the associated relays in the furnace circuit board have been known to cause problems as well.
 
Dennis,
The only difference between mine and yours is that mine has the front furnace as well. This is the furnace that comes on, not the rear one. I thought the same thing that maybe I didn't have the switch in the correct position, but that wasn't the case. The ambient temp this morning was 75, so I don't think that the thermostat and furnace are operating as designed as someone had suggested. I will take yours and Lou's advice and start looking at the thermostats and wiring.

Thanks!
 
Oops - the difference in the intellitec controller is that mine has the rear furnace. Sorry about that!  :-[
 
George, I had a similar problem - heater took on a mind of its own, starting in the middle of a warm day, etc..  Mine is located directly under the fridge (common configuration) and when I accessed the panel and took out the circuit board I found that everything was soaked.  The drip tube in back of the fridge had somehow been moved so that it didn't evacuate to the outside like it's supposed to and had created a healthy puddle, which eventually leaked down to the heater equipment.  I took everything out, completely dried the motor, replaced the circuit board and rerouted the drip tube in the fridge compartment and everything has been fine ever since. 
 
Thanks. From what you nice folks have been reporting and what I have been able to pull off google searches, the thermostat is the likely culprit. Does anyone know of any wiring schematics for these furnaces? The thermostat doesn't appear to be cheap, and I don't want to throw parts darts unless necessary! It does make sense to be the thermostat, but I only have 8.5 volts coming into it, which may or may not be normal, as everything else functions normally and the coach batteries are strong. I spent a lot of time yesterday trying to figure this out. While taking what I think are the power and ground wires off the thermostat, I heard a clicking noise coming from the electrical service, which is above the refrigerator on my coach. Turns out that it was coming from the electronic climate control unit. I didn't take the unit out, but did disconnect and reconnect connectors. I also tried resetting everything, as was recommended in other posts, but that didn't do anything to help. 
 
OK - I'm convinced that the thermostat is bad. It is an Intellitec 00-00597-000. The best price I have been able to find is $137.00 through rvpowerpartsplus.net. Anyone know of a better place and price?

Thanks!
 
The furnace lead designation is the "W" lead if you can get access to the wiring behind the thermostat. If disconnecting that lead from the thermostat solves the problem, you have found the answer. (Normally the thermostat applies 12V to that lead when the furnace is required.)
 
Thanks Stu. The problem is constant now. As soon as the front furnace blower kicks on - with the thermostat in the off position - I disconnect the 2 wires at the thermostat, and the furnace cycles off. Once it cycles off, I plug the wires back into the thermostat, and the front furnace starts again. Based on the troubleshooting tips from the info supplied by the good folks of this forum, there are only 3 possible causes for this:
1) Chafed wires to the thermostat, causing a short circuit - I have ruled this out.
2) Relay that controls the furnace stuck closed contacts - this isn't possible, as disconnecting the wires from the thermostat would have no effect.
3) Faulty thermostat. This is a high fail unit from what I have read, and since the first 2 possibilities have been eliminated, I am confident that this is the cause of my phantom furnace issue!
 
Good troubleshooting!! The only thing I could add is that Just removing the W lead should prove it. The terminal on the thermostat will likely have 12V on it when the trouble is there. The 12V is controlled by one of those miniature relays on the thermostat and tapping it may cause the problem to disappear, not that it matters, you still have to change the thermostat anyway. (RVP thermostats are notorious for bad relays and switches, at least in my experience!!)
 
Try sending this guy a message on ebay- http://myworld.ebay.com/rvpartstogo/  He may have one in stock.

I know he sold one to a buddy not too long ago for $99.00
 
Replaced the thermostat on Friday, and everything has been operating normally since. Thanks to all for the advice and direction. I did learn something that may be of use to anyone else having this concern. The circuit boards that make up this thermostat are the same whether you have 1 or 2 furnaces. The only difference in the part numbers is the faceplate. I found this out because the thermostat I ordered for my coach was for the dual furnaces, but it was on backorder for at least 2 weeks. The customer service folks at RV Power Parts Plus contacted me to let me know that they could send the single furnace unit out and all I needed to do was change out the faceplates. I had my doubts, but the only difference between the 2 is that the single furnace unit is fabricated so that the switch cannot be moved up 1 extra notch, which is what would turn the rear furnace on in a dual furnace unit. Straightforward exchange, and everything seems to be operating normally again.
 
You must log in or register to reply here.

Latest posts

Members online

Total: 565 (members: 29, guests: 536)

Forum statistics

Threads
132,174
Posts
1,391,454
Members
137,886
Latest member
Bob007
Back
Top Bottom