AC/Furnace Control Box

We've had the mobile tech out three different times to repair our ac/heat system in our first month in our 2014 Bighorn Silverado 35 RES. It will run a day or two and then the thermostat goes blank. We've replaced the control box twice, but the problem persists. We are now into 90 degree temps and don't see any progress.

Our tech says this is a new design and suspects feedback through the furnace wiring. Any assistance would be greatly appreciated.

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danemayer

Well-known member
When you say you replaced the control box twice, are you talking about the thermostat, or the control box in the ceiling with the air conditioner? The thermostat signals a control box in the ceiling to turn on the furnace or the air conditioner. You could have a problem at either end.
 
I am referring to the box in the ceiling. We've also tried replacing the thermostat, but there is no juice to the stat. There is a 6 volt reading coming from the furnace when it is turned off as well. Thanks for taking an interest!

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danemayer

Well-known member
Where are you measuring the 6 volts from the furnace? And are the rest of your 12V systems working? Interior lights, refrigerator?
 
Everything else seems to be working okay, although I did notice the hd side of our Directv seems to be on the fritz, now that you ask. The six volts dropped from 12 when we pulled the furnace fuse.

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danemayer

Well-known member
I think that's supposed to be 12V. Have you got 12V at other places in the coach? If yes, I think you need to run down why it's 6V at that location.
 

danemayer

Well-known member
Here's the furnace wiring diagram. 12V.
 

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  • Suburban SF-20-25-30-35-42_Furnace_Wiring.pdf
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That's what the tech thinks as well. He's asking permission to rewire the furnace on Monday. I will pass this along to him.

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danemayer

Well-known member
Have to wonder where the 6V is coming from and why the furnace fuse was pulled. And was the thermostat working with the furnace fuse plugged in?
 
Didn't make any difference to the thermostat. When it goes blank, it never comes back. No juice from the ceiling control box out to stat.

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Update on this problem. Tech was back and replaced the ceiling control box again. This time he didn't connect the furnace to the control box. AC appears to be working well, but still have the furnace issue to contend with. Tech is trying to get Heartland to authorize more time to trouble shoot the furnace issue. Can't complain about Heartland service, as they have been very patient.

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