SAIL SWITCH VOLTAGE CHECK
Hoping for help on troubleshooting a Furnace Sail Switch. Furnace was intermittently failing and now progressively worse. Blower would come on and after about 30 seconds would shut off - no audible at...
Forum Discussion
enblethen wrote:
Not a very good drawing but may help.Wiring diagram
Interesting the sail switch is tied to thermostat.
You could have thermostat issue.
Fan would not turn on if it was a "T stat" issue.
T stat delivers 12V to sail switch and terminal on control board marked "air".
Sail switch contact must close to complete circuit to control board (apply 12V to the control board input terminal) to initiate ignition.
I doubt the issue is the sail switch and is most likely a fault in the control board. Sail switch is not carrying any more current than the T stat so contacts should not be burnt and as long as the sail switch contacts are enclosed, dirt should not an issue.
You could test that theory by jumping in a manual switch to bypass the sail switch which you can flip on after the fan motor has started.
If no joy, then the issue is not the sail switch but rather the control board.
Not unheard of to have a control board go south.
