Suburban heater/furnace

[Dave Sweet]

My sf-35q heater won’t put out heat after replacing the limit switch and the sail switch. Any ideas?

 

[Capacitor]

What caused you to replace limit and sail switch? First thing that happens is the blower runs, does it?

 

[Dave Sweet]

The fan comes on with out any heat. It tries to ignite, but goes out immediately.

 

[Capacitor]

https://thecampingadvisor.com/suburban-sf-35-furnace-troubleshooting/

 

[Dave Sweet]

Thanks. I'll check it out.

 

[5picker]

What caused you to replace limit and sail switch? First thing that happens is the blower runs, does it?

I'll ask this too.

Those parts aren't maintenance items so there was a reason you replaced them.

Give us the whole story and we can give better answers.

 

[Capacitor]

Well, the sail switch works as you got this far in the sequence. Next is the gas valve opens and igniter sparks, gas lights and igniter sends a flame proving signal back to circuit board telling it to stop the clicking and hold gas valve open. This is where the failure is. Possible corroded ends on igniter not allowing signal back ( milliivolts) or weak connection with spade clip on igniter. Clean igniter with emery cloth or coarse sandpaper. Check gap 1//8 to 3/16. 1/4” nut driver and carefull with the gasket.