No Heat in NoDak

Diver960

Member
I own a 2011 Big Country 3450TS (purchased 5 Oct 12), that is currently parked in a full time lot in Dickinson, ND. I have it very well insulated and all lines wrapped, and have had no problems even in negative temps. Then I went south for Christmas, and left the BC in place while I was gone. To prepare for my trip, I turned the main water supply line off, but kept water in the lines; flushed the septic out and put 5 gallons of fresh water in the tank with a smell good additive; turned the heater thermostat down to 50, and felt i had done all I needed to do. Everything was working perfectly until I returned yesterday. I drove straight through (17 hours) and walked in at 0130 hours to a camper that was colder inside than out. Thankfully, everything else is working, so I turned the fireplace on, put a space heater in the bedroom and Miles (my mini-schnauzer) and I slept pretty good. Guess the years in the infantry helped me there, while his fur and sweater helped him. Anyway, I feel I have checked everything out and need some help. I got the water lines thawed to find a major leak behind the toilet, so with the water turned back off, and as we're under the covers sipping bottled water, I am considering the furnace and what may have happened. I've recycled the thermostat as told to do by the manuals...nothing. The propane is flowing perfectly, as the stove works, the hot water heater works and I am hooked up to a new 250 gallon tank. There is clicking when I turn the thermostat on and off and when I try to get the blower to work, I hear a hum...so...everything seems to want to work, but I can't get the blower to work. ? Have hung a 75 watt bulb over the unit downstairs, and could really use some advice here. Anyone have a similar problem or ideas that may help me? My fiancé called from her nice, warm southern home and said she had heard something about a sail switch? Huh? What and where is that? Thanks so much...appreciate any ideas and feedback.
 

danemayer

Well-known member
Hi Diver960,

When the thermostat calls for heat, current flows to the motor to operate the blower.
As the blower turns, it blows air against the sail switch (inside the furnace) and
closes the contacts (at approximately 75% of the rated air flow), completing the circuit.
The sail switch is a safety device (air prover) that insures adequate air flow before ignition.

If you don't hear the blower running and no air is coming out of the ducts, something's failing prior to the sail switch.

If the blower was running when you got back to the trailer, but pushing cold air, that's an indication that the furnace failed to ignite.

The thermostat operates a relay that supplies power to the furnace. If the hum or clicking you hear is inside the coach, maybe overhead, it could be that relay. It's probably located in a metal box above the A/C return air in the kitchen ceiling.

If the blower fails to run, possible causes are:


  • No electric to the furnace - blown fuse
  • Loose wires at the thermostat or at the ceiling relay
  • Loose wires at the furnace
  • Defective thermostat
  • Bad blower motor

    If other 12V systems are all working properly (lights, frig), it's probably not a problem with the power converter and battery. But if you're having problems with other 12V systems, check voltage at the battery when plugged into shore power. Should be >13V.


 
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