Furnace not blowing

[stew47]

Hello all. I have a 1998 Winnebago adventurer 35wp. While camping I tried to run furnace and it wouldn't blow air out the vents. Fan is running though. I'm not super familiar with furnace as I am always plugged and in use an electric heater. I'd like to see if ductwork came apart but.... I don't know how to get to furnace haha. I'm assuming it's under closet. What's easy way to get to the furnace?

[stew47]

Ok time to resurrect old thread! I finally had a little time and good weather to tear into things. Was quite a chore getting to furnace from outside. Everything is kind of dirty and while taking a test light to the sail switch and it lit and took off. So I figure I will blow everything out with air compressor and clean and tighten maybe wd40 the sail switch. Should I do anything else?

[Ron_Nielson]

The service manual has a good troubleshooting section

Suburban Troubleshooting

[stew47]

I've never cleaned it but I've only had it 9 months. I'll see if I can score an air compressor here at campground.

[enblethen]

When was the last time the furnace was cleaned out? It could be just dirty causing the sail switch not to operate. Can blow it out with air compressor or can of computer air. Could try strong vacuum, but I have better luck with compressed air.

[stew47]

Well I was wrong. Air blows out the vents. I was just checking furthest vent and not much air comes out. First vent has plenty of air. I never hear the igniter. The fan will run until I shut it off. I read that blower will shut off after furnace fails to light. Well I'll try to figure out tomorrow.

[stew47]

Oops that model is wrong. Suburban sf 42. I found the book.

[nineoaks2004]

If none of the other solutions work you might check and see if the duct work might have a hole in it or has came loose somewhere.

[stew47]

Well it looks like the model number is mh 12340 not sure of brand. I can see part of the top of furnace by removing closet floor which was just set in. To access the furnace fully it looks like the exterior panel has a hinge and a few screws holding it. I pulled those screws out and then pulled screws out of exhaust grill but I couldn't pull the grill out so I couldn't open the door.

[jrnymn7]

"While camping I tried to run furnace and it wouldn't blow air out the vents. Fan is running though"

Are you sure the swirl cage is turning, or is it just the motor you hear running?

Is the return air duct blocked off?

[Artum_Snowbird]

It could also be that you have plugged off the opening. There should be a grilled vent somewhere that lets air in.

Certainly, if there is no airflow, there should be no furnace with hot air flowing.

Put your furnace model into a google search for the service model and read about it before you tackle it.

[enblethen]

Locate make and model of furnace and post information.
It is possible that the fan squirrel cage fan has come loose on the motor shaft. It is the larger of the fan blades. Might be able to check by using small stick through opening to see if it moves with out the motor. Turn off furnace power.
You may even be able to see it with the fan motor running.