Community Forums

Mike and Pat · 02-05-2007, 02:16 AM

I am having a problem with my Suburban Gas Furnace model SH-42. I have a 2004 Itasca Meridian 39K. It started 2 weeks ago. The furnace fan comes on but the furnace will not light. It doesn't happen all of the time and can be above or below freezing. If you shut it off and then back on a few times it will finally fire up and you will getwarm air. The biggest problem is that you can have warm air during the night and then it will not light and the system shuts down. Any suggestions?

Mike and Pat · 02-05-2007, 02:16 AM

I am having a problem with my Suburban Gas Furnace model SH-42. I have a 2004 Itasca Meridian 39K. It started 2 weeks ago. The furnace fan comes on but the furnace will not light. It doesn't happen all of the time and can be above or below freezing. If you shut it off and then back on a few times it will finally fire up and you will getwarm air. The biggest problem is that you can have warm air during the night and then it will not light and the system shuts down. Any suggestions?

paz · 02-05-2007, 04:57 AM

Mike - Welcome to irv2.

There are a number of things that could cause the problem you describe. The first thing is to make sure nothing is blocking the cold air intake inside or the exhaust vent outside. Does your Meridian furnace use the air filter under the bed? I don't know if it does of if that filter is just for the air conditioner. If the furnace draws air through the filter, make sure the filter is clean and that nothing has shifted to block it. Wasps and spiders sometimes clog the outside vent. I also assume you are plugged in and low voltage is not a problem.

If the intake and exhaust are clear, I think the next most likely cause would be the sail switch. This switch checks for adequate exhaust flow before allowing the gas to come on. If the switch is hanging up or faulty, there will be no heat.

"007" · 02-05-2007, 09:16 AM

Welcome Mike Montgomery to irv2.

Check as "paz" said also you could be having problem with gas regulator on tank freezing up, all valves open fully. Some others will chime in here so enjoy the forums and post often.

Retired and Happy · 02-05-2007, 05:15 PM

Is your fan motor running up to speed? If it's slow, either from corrosion, dry shaft, or low voltage, the sail switch will not sail and the heat cycle of the furnace won't start. (Spoken from current experience on a similar heater.) On mine, the same dual ended motor runs the two fans for inside heat distribution and exhaust. In my case a new sail switch did not improve things. When the weather gets warm enough that I won't need the furnace, I'll work on the motor.

RV Wizard · 02-05-2007, 11:54 PM

Mike & Pat, welcome to iRV2.com. We are glad to have you join us here and look forward to reading of your adventures and experiences. Sorry to heart of the trouble you are having with the furnace. THe #1 problem with these are pest building nest in the combustion chamber, burner, ignitor area. The #2 is the connection to the ignition board. I would suggest you clean the contacts at the board first since it is the easiest to get to. If that fixes it, good. If not then clean the burner area and make sure the spark gap is set to about 3/16" from Burner and the burner is clean. Goo luck and let us know how you do.

Mike and Pat · 02-06-2007, 07:31 AM

Thanks everyone for their suggestions. I have started to go through all of the common areas and everything looks good. I found the intake it is under my dresser. I took out the drawers and looked and did not see any blockage. It stoped again last night just as the temperature was dropping to 20 degrees. At 3am I found this out and stayed up for 45 minutes trying to make it recycle. it finally started producing heat and i went back to bed. It only got to 66 inside so not bad. This morning I removed the drawer again and stuck my hand down into the hole for the intake and found a small box (4" x10") i removed it and the heater started up. I will wait until it get cold again tonight and see if it stays working.

troth · 02-06-2007, 09:07 AM

OK, Mike and Pat, I'll bite!!! -What was in the box you found?

Dsouthw524 · 02-07-2007, 04:59 AM

If removing the mystery box doesn't cure your problem I suggest you have a bad circuit board. I base that on our experience as we had problems with our furnace last year. two dealers worked on it and it did not show problems when it was "on the bench" After re-instalation the furnace failed. New circuit board was installed at the second dealer and the problem has gone away. I suspect that the hheat in the enclosure for the furnacee was caausing the printed circuit to open.

Hope you havee heat.

Mike and Pat · 02-08-2007, 02:01 AM

Well, removing the box has seemed to have fixed the problem. It has run now for about 36 hours with no problems.

What was in the box? A HEPA filter for an air cleaner.

Retired and Happy · 02-08-2007, 02:16 AM

I hope your problem is solved and you have no further furnace problems. I guess we can conclude a filter in a system is not always good, even if it is a HEPA filter.