SOLVED: Suburban SF-42Q not coming on [replaced control board]

S

Swhoward1971

Member
A few days ago my wife said the only time the furnace would come on is if she cycled the thermostat. Now it is not coming on at all. When I cycle it i get a click then about 30 seconds later i get another click no fan or anything else. I have checked all I can and looked everywhere I can. I have checked the sail switch and disconnected the motor and wired it direct to battery fan works just fine even swapped propane tanks and stil nothing. There is no mobile repair in the area and we are skirted for the winter. Any help or direction would be greatly appreciated.
 
danemayer

danemayer

Well-known member
Re: Heater not coming on Suburban SF-42Q

When the thermostat calls for heat, it fires a relay located overhead. That's the click. That relay supplies 12V DC to the furnace control board to start the blower. Then after the blower gets up to speed, the sail switch closes and the board opens the gas valve and fires the igniter.

If the blower doesn't start, you might have a blown fuse in the fuse box, or a loose wire at the furnace, or a failed furnace board.
 
Roller4tan

Roller4tan

Well-known member
Re: Heater not coming on Suburban SF-42Q

similar issue here, found power to board on start up but no power to fan. Relay on board bad. Got new board online from dinosaur electronics. Fixed my furnace.
 
dave10a

dave10a

Well-known member
Re: Heater not coming on Suburban SF-42Q

I had a similar problem, After much troubleshooting I isolated the problem to be the control board which I replaced with a better quality board. Saying that it is my hope that some day RV manufacturers put a little more effort in design to allow for easier troubleshooting and repair.
 
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