Suburban SF30-F Furnace

[myowneq]

Hi, My furnace quit working. The blower would blow, but no heat. Batteries have plenty of power and Im plugged in. I checked the intake and exhaust and all clear. Propane tank is full and the stove is burning all 3 burners nicely.

So I removed the furnace to start testing components. The igniter sparks, the sail switch operates well, the hi temp limit switch has continuity.

The only problem Ive found is the gas solenoid doesnt open consistently. I applird 12v to each terminal and it clicked every time. Held it open for 2 mins.

So Im thinking its the control board. Does anyone have any input to support or dismiss my diagnosis before I spend $80 on a new board?

Thanks. 🙂

[dougrainer]

All you do is see if you have 12 volts to the gas valve when the ignition cycle starts. Either you DO or you DON'T. If NOT, and the Spark electrode clicks the Circuit Board is bad. Doug

[Chris_Bryant]

Make sure the board connector is good, I have had one of the contacts crack, so it looked good, but didn't actually make contact.

[myowneq]

When operating the solenoid manually (direct connection to a battery), it works every time. However, when attached to the system, it doesn't.

I'm the 2nd owner. The furnace is likely original to the trailer. I see no evidence to the contrary. That makes it 10 years old. The overall condition of the furnace is in good shape. No rust spots, corrosion, pitting, etc. I found a couple wires where the mice nibbled at them, and fixed that.

So, it comes down to the solenoid, which works when operated manually, doesn't work when connected to the circuit board.

[dougrainer]

You don't state how old the furnace is. But, If I suspect a Gas Solenoid Valve, I whack it with a hammer when trying an ignition cycle. If it opens the solenoid is bad and I replace it. Doug

[Chris_Bryant]

I'm missing if the solenoid did or did not open each time.
Did you check the orifice for debris? That is by far the most common problem I see with this model with your symptoms.

[rhagfo]

myowneq wrote:
Of the 9 times I tried it, the solenoid opened once as it should have.

More like consistent failure!

[myowneq]

Thanks for that service manuel. 🙂

[myowneq]

Of the 9 times I tried it, the solenoid opened once as it should have.

[lawrosa]

Here is the service manual....

http://www.trekin.digital-digs.net/Share%20PDF/Furnace_Service_Manual.pdf

[Joe417]

Sound like you've checked everything. Why did you use the term "consistently". Does it work some of the time?