Furnace not working

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Some problems can end up being something real silly. Read this and go back to reset and reprogram.  BUT I dont want you to end up with nothing either......so dont reset it if you cant program it.

http://www.rvforum.net/SMF_forum/index.php?topic=84810.0

http://www.rvforum.net/SMF_forum/index.php?topic=38922.0

Read through these posts as merc talks about checking connections in the control box and an green led coming on. Be careful of 120 volts from shore power possibly.

http://www.rvforum.net/SMF_forum/index.php?topic=38922.0
 
Don't know how to reprogram it but did check control boxes and everything looked attached and fine.  Didn't see any LED's in the boxes though.
 
I have the same thermostat.  On a couple of occasions it has gotton lost or lost its program. If I remove the thermostat from the wall and unplug it or a few seconds, it resets to normal.


Ernie
 
If the thermostat was replaced recently, it may not be unusual to find it defective from the beginning, especially if the furnace start was not tested at the time of installation. I went through two new RV Comfort thermostats that had defects before getting a third good one several years ago. Fortunately they were all on warranty.
 
I have a HVAC tech who mainly works on home units coming out.  At least he understands how these things are supposed to work.
 
It appears that one of the circuit boards on the furnace is malfunctioning and when I looked for circuit boards on Amazon, it was the first one that popped up.  That might tell you something.  Will report when we get it installed.
 
Well,,, plugged the new circuit board in and, you guessed it, didn't fix the problem.  Really has the tech puzzled as power comes in to the board, but does not come out,,, same as the old one.  What are the chances of two boards being bad in exactly the same way.  Troubleshooting specs say, if this occurs, the board is bad.  He is going to try to talk to someone at Suburban next week to see if he can get some advice.
 
There are inputs and outputs. You need a schematic that splices all the systems together and be able to look at the whole system showing the furnace, ac, control box, generator etc and how they are connected together. There is a sequence of operation. You look at the sequence of operation and go step by step looking at the components and what inputs they need. If you find that the inputs are ok but a card isn't putting out it mat be because it needs to see other certain things happening.
 
QZ said:
There are inputs and outputs. You need a schematic that splices all the systems together and be able to look at the whole system showing the furnace, ac, control box, generator etc and how they are connected together. There is a sequence of operation. You look at the sequence of operation and go step by step looking at the components and what inputs they need. If you find that the inputs are ok but a card isn't putting out it mat be because it needs to see other certain things happening.

That makes sense and really is the only possible solution.
 
Gary RV_Wizard said:
If you are at an RV dealer shop, I would not want to bet on it.  :(  They are notoriously poor at diagnosis....
Exactly, and that's a shame. I had to help one RV "tech" figure out which solenoid was the battery mode solenoid (the house disconnect solenoid was nearby.) The kid was really thrashing around and had no organized approach to problem solving.
 
QZ said:
Have you set the furnace manually to "Gas" operation which seems to bypass the heat strip function?

http://winnebagoind.com/resources/manuals/pdfs/Operator2014/14Suncruiser.pdf#page=53&zoom=auto,-39,788

Uh,,, as far as I know, there is only one way on the thermostat to run the furnace, but it really doesn't matter right now as the furnace is out of the coach and sitting on a bench in my garage.  If the tech can't figure it out, there is a Suburban service center not too far from here.  Maybe they can bench test the unit.
 
Peteyboy said:
Uh,,, as far as I know, there is only one way on the thermostat to run the furnace, but it really doesn't matter right now as the furnace is out of the coach and sitting on a bench in my garage.  If the tech can't figure it out, there is a Suburban service center not too far from here.  Maybe they can bench test the unit.

I may not be following along correctly but didn't they do that at first? I'd have to go back and look but does you furnace harness plug have four wires? 12 volts pos and neg plus two blue thermostat wires?
 
QZ said:
I may not be following along correctly but didn't they do that at first? I'd have to go back and look but does you furnace harness plug have four wires? 12 volts pos and neg plus two blue thermostat wires?

Yep,,, sounds like the plug.
 
After reading the thermostat link again I go back to the control box led that should be on. It says that if it's not lit there is a 12 volt problem. As owners of the RV we have to learn the systems but the tech could be going around in circles and burning money on parts if he doesn't understand it.  You need a tech who knows the therm and be able to walk you through it. Maybe the service center has someone who can go over the thermostat with you.

 

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