Need help with a SF 30 Suburban Furnace
My original problem was the usual story. The fan would come on and the furnace would fail to light and the fan would then shut down. I, standing outside could hear the switch and smell gas but the spa...
Forum Discussion
enblethen wrote:
It is the two blue wires that come from the thermostat.
Red and yellow is the 12 volt DC supply.
Red is 12VDC + (positive)
Yellow is 12VDC - (negative)
Red supplies 12VDC+ to the thermostat via the On/Off CB Switch (local/on furnace frame) (Blue) and DC Power to 'power' circuit on board
Thermostat closes and sends DC+ back to circuit board (Blue) and sail switch/limit switch circuit
Connecting the 2 Blues wires at thermostat makes up 'run' circuit...bypassing thermostat
If Furnace runs (Fan/Flame/Heat) then thermostat is problem
If furnace does NOT...check if the on/off CB switch is tripped///push button reset
