Suburban furnace starts then shuts off

[scooter21]

2006 Itasca Suncruiser with Suburban furnace. Heat pump works fine, but the when I switch the thermostat over to gas heat the fan runs for 20-30 seconds and then the furnace turns off. There is no audible click from the thermostat when it shuts off, clearly it's shutting off at the furnace. During the short time it's running there is air but no heat coming from the floor vents, as well as from the furnace exhaust port at the rear of the coach. It seems the furnace is not lighting. I have a full LP tank and good LP flow to both stovetop and fridge. Thermostat temp is set well above inside temp (68 vs 59). Any suggestions?

Thanks!
Scott

[jlfbatonrg]

First, on all RV furnaces, the blower comes on first and runs for several seconds before the furnace ignites. This is to purge the system of any excess propane. The first thing to check is the off/on valve on the propane regulator. You should be able to access this throught the outside cover. Make sure it's on. Next thing to check is your voltgae going to the furnace. It if it too low the furnace will not light. If the DC voltage is good, there are several safety features built in starting with a sailswitch that will not permit ignition if the air flow in the furnace is too low. Assuming you have enough air flow the next thing you should hear is the ignitor trying to light the propane flame. The furnace will try to light 3 times, then shut down if the propane doesn't light. Set the thermostat to gas heat, then get up against the air intake and listen for the ignitor to try to light the propane. If it dosn't try, there are many potential problems, including the control board, alignment of the ignitor, or the ignitor itself. If it trys to light but doesn't, you may have to try it several times to get the air out of the propane line going to the furnace. Is it still doesn't light I would suspect looking in the propane control valve area. I would first remove the positve feed to the solenoid on the propane valve, and connect a voltmeter to it and to ground. Cycle the furnace and see if you have the proper voltage is feeding the solenoid. If you have voltage, reconnect the wire and cycle the furnace again. See if you can hear the solenoid activate the valve. if no, the solenoid could be bad. If you haven't resolved the problem, I think the next step is to remove the furnace where you can put it on a bench, and continue the diagnosis. Good luck.

Jim

[RVThere]

I had the same problem on my furance in November.

A quick test/fix is to tap on the propane solenoid with a screwdriver handle while your partner turns the furnace on. Sometimes that solenoid sticks. You need to take the outside cover off and look for a gold cylinder with a plunger type rod in the middle. Keep tapping while the fan is blowing and you should hear it light and the fan will keep running.

["007"]

If the gas does ignite but flame goes out the sensor within the ignition flame may need to be cleaned because its not sensing the ignition flame.
At the top of this forum there are stickies with your furnace information.

[DTBarton]

Scott,
I'm a full time rv'er living in Michigan year round. I been fighting this problem for 2 winters going on my third. The problem is the furnace is starving for gas. After several calls to suburban and talking to there tech's with no results trying there suggestions and my local rv repairman again no results. I went to a little ma & pa's rv dealer for a limited switch to try agian. Talked to there service manager. He told me to put a test tank straight to the furnace to see if it would work, instead I put a tee on my regulator and ran a half inch stainless steel flex line straight to my furnace. I'm on my third day with the furnace working just fine.

GOOD LUCK!!
Dennis