Suburban Furnace

[68LANDYACHT]

Hi folks, I sure hope someone with some "expert" knowledge can help me out. I removed my Suburban furnace from my 68 Ambassador, disassembled and cleaned, repaired the fan and ran a bench test. The little fella fired up and ran great. Reinstalled it and now nothing but click, click, click when the thermostat is activated. Bipassed the thermo.......same thing. The pilot light remains lit throughout. Any ideas what the problem is? I would appreaciate any advice given.

[bobechs]

and this may be something you have eliminated as a cause, but are you SURE you are getting propane to the furnace? Hissing alone is not proof if what is being delivered is air in the supply pipes, which does not burn well.

Whenever I have opened the supply piping, it has been a process to get burnable gas to all the appliances. Lighting the stovetop helps to move the propane through, but it is usually still something of a struggle to purge all the air.

[thenewkid64]

Does the blower motor spin up? I would check the wiring to it first. The click you are hearing is likely the motor start relay. If the blower is not blowing the main burner will never ignite

[68LANDYACHT]

When I ran the bench test all seemed well. I didn't even need to adjust the flame on the burner. When I reinstalled it is when all I got was the clicking response. It is not getting gas to the burner at this present nor will the fan activate.

[thenewkid64]

I would be willing to bet a wire has been knocked loose to the fan motor, or the reinstall has jammed the blower somehow.

The typical start up sequence is as follows.

Call for heat

Start fan. I think this is the click you are hearing, but no spin on fan motor.

See sail switch close from force of air blowing in heat exchanger

Open gas valve to light main burner. The gas valve will not open if pilot is not lit due to thermocouple safety system. On an electronic ignition model this would be the igniter's job. There is a temp probe that must be satisfied to maintain operation even then.

Blow heat.

Shutdown:

Temp. reached

Shutdown burner by closing main gas valve

Run fan until exchanger has cooled to preset temp or for a preset amount of time.


So until the fan spins the main burner will not light.

[68LANDYACHT]

I'll try the replacing relay first. Maybe I'll get lucky. Thanks.

[74Argosy24MH]

Jumper around the relay and see if the fan works.

John

[garry]

Sail switch can be checked with an ohm meter. Just because it moves does not mean it is good. However; since all worked on the bench then I agree with the others no gas. It takes me a good 5 min or more to purge the air after reconnecting the gas line and that is after turning on the range burners.

Garry

[68LANDYACHT]

Would that apply, Garry, considering the pilot was/is burning fine?

[thenewkid64]

If the pilot was burning fine, then the gas IS to the main gas valve on the furnace.

If the blower motor does not spin, you are in a lock out situation the rest of the unit will not function for safety reasons.