No gas to the suburban furnace

[Clarkboulder]

According to the Youtubes, If the Sail or Limit switches are bad the system will only run for a hand full of seconds (-/+ 30s) and then shut off. Mine seems to run indefinitely despite no gas ignition. Is this indicative of anything else?

[Clarkboulder]

True. I can partially see inside the fan housing with fan blades running but not the rest or the ducts. But the fan works fine Clean Air is coming out after clearing initial dust build up from dirt road drives.

[arctictraveller]

Its easy to confirm that gas is flowing at least as far as the heater by disconnecting the hose where it attaches to the heater after turning off the valve at the tank. Then crack the tank valve and give it a quick blast, if a fair amount of gas escapes, the problem is down stream of the hose at the heater. Obviously do this in a well ventilated area, but a quick one second blast won't accumulate much gas, and it will bleed out the air in the line too.

[Clarkboulder]

So as I suspected, if the electrode is sparking, than the the system is working all the way to that point. That means the Sail and Limit are all working or otherwise it would not spark. What I wasn't sure about is what this pointed to. According to this video,

https://www.youtube.com/watch?v=zCp_HXPaC8U

it suggests the solenoids or gas valve. But need to check the Solenoids first.

[N147JK]

Originally Posted by Clarkboulder

So as I suspected, if the electrode is sparking, than the the system is working all the way to that point. That means the Sail and Limit are all working or otherwise it would not spark.

If the switches aren't working the valve will not be allowed open. The lighter doubles as a thermocouple. If the thermocouple stays cold for too long the system will purge the combustion chamber to ensure no gas is left over and then shut down. The cycle has to be restarted.

Best thing to do at this point, as I suggested before, is to put a meter on the valve solenoids.

[Clarkboulder]

UPDATE:
I checked via multi meter the Sail Switch and the high Limit switch and both seem to work. This might suggest the solenoids have failed since I don't hear what I would expect to hear of the clicking of the solenoids. But I don't really know how to check these. I think I need a power source so I bought a small 12v 7Amp battery.
What do I do next?
Is there a way to remove and test them individually?
Do I need some jump wires?
Can I replace just the solenoids if one or more are bad? I only see the whole gas valve with solenoid for sale at PDXRV or on the web.

[arctictraveller]

https://manuals.heartlandowners.org/...11-05-2015.pdf

From the service manual page 32: "Electrode sparking, but gas not coming through burner:
a.Check to see if voltage is coming out of module board
to gas valve after the 12 - 18 second delay. Check the
wires in the molex connector to be sure they are intact
and making contact with the module board. Check wire
from the module board to valve for continuity. Wire and
connections check OK - replace module board.
b.Voltage is coming out of module board to gas valve, but
gas valve does not open - replace gas valve.

[N147JK]

Sounds like you are on the right track.

I think there is a way to check the solenoid by measuring their resistance. But really to be completely certain they are working or not, what I did was (with the unit out of the van) blow air through the supply line while energizing the solenoid. Doing this, you will immediately find out whether the solenoids are actually operating the value properly or not.

Any 12V power source will do to operate the solenoids. If you need to use jump wires to reach a battery, that is OK.

One thing I learned.. it's considered a no-no to open the solenoid or the valve. This I suppose is because they are safety-critical items that are not supposed to be worked on at home. I ended up replacing the valve (it comes with the 2 solenoids) with all-new instead of trying to monkey with it myself. Now I know my system is renewed and safe. Also completely cleaned out the insides. Works good as new!

Yes your are correct - you should hear a good strong "click" if they are operating correctly.

[simplesez]

Originally Posted by Clarkboulder

UPDATE:
I checked via multi meter the Sail Switch and the high Limit switch and both seem to work. This might suggest the solenoids have failed since I don't hear what I would expect to hear of the clicking of the solenoids. But I don't really know how to check these. I think I need a power source so I bought a small 12v 7Amp battery.
What do I do next?
Is there a way to remove and test them individually?
Do I need some jump wires?
Can I replace just the solenoids if one or more are bad? I only see the whole gas valve with solenoid for sale at PDXRV or on the web.

I'm confused. The video you linked specifically shows how to test the solenoids with a power tool battery and a can of air. Did you not watch it?

Take the unit out and bench test it. The gas valve and solenoids are easy to access with the unit out.

You should definitely hear the clicking of the solenoids when turning on the furnace. Without gas the furnace computer will shut down the system after 3 tries. It takes a while but it is a safety feature.

[Clarkboulder]

Update: So I energized the solenoids and they work.
Because I could not figure out how to disconnect the valve from the rest of the gas line to the chamber w/o damaging the valve or the line (see photos). I had to settle for sending forced air through to the chamber and the orifice. So I looked for air coming out of the orifice inside the chamber. It blew out a small flame each time the solenoids were energized. So I assume this means the solenoids work.
Next I tested the gas line in the van to the tank. Slightly opened the tank and gas came out of the supply line that would serve the furnace. So that rules out the regulator. (or does it not?) Could the regulator be not providing adequate pressure? (My two burner stove works fine but one of the burners does have a taller yellow flame instead of short blue one.) I see the service manual states the Water Column pressures needed at orifice and valve. What type of mechanic would/could or is qualified to check that?

I'm told by @simplesez that he replaced the module board a few years ago. I suppose this could this be the problem again? Any way to test that? I see the service manual states some bulb flashing diagnostics of the lights that come on during operation but I think I observed all that? I am not able to follow everything it states as its not in my knowledge base.