| Suburban Furnace [message #227263] |
Sun, 27 October 2013 18:58  |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
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I finally had a chance to work on the Suburban furnace on my 78 Royale. I have researched and read various posts here so I think I am on the right track but would appreciate any insights.
I believe the sequence for the furnace firing goes something like this:
1. Thermostat calls for heat and activates the blower fan motor.
2. Fan blowing starts time delay before electronic ignition is energized to create spark
3. Fan blowing also moves "sail switch" to complete a circuit and allow the gas valve to open.
In testing mine, the thermostat works, blower motor works, and I am able to confirm the spark from the electronic ignition as I can see it through the sight glass. It is not lighting so I have suspected the electric gas control valve?
I took the gas line off and confirmed that I am getting propane to it, but I do not smell any unburned propane coming out the vent, again leading me to believe that the gas control valve is not opening?
Here is my specific question. Does a fault with the sail switch prevent the gas valve from opening, or does the sail switch prevent electronic ignition? Since I have ignition, does that mean the sail switch is ok?
I have done a good cleaning of the blower assembly and vents. The blower was clogged with lint and junk. The vents were clogged with the typical bee nets. My initial check inside the burner looked ok. It did not seem to be clogged and not much rust. I will open it up more next chance I get. Although it is a no no to "hot wire" the sail switch I will probably do that briefly for testing purposes only.
Does anyone have knowledge or experience with the gas control valves?
I also realize that the valve could be good and the circuit board is bad.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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