Furnace

[03heritagerider]

Didn't know exactly where to post. This also appears in "Electrical" forum.

Last week I ran the furnaces on the way to Florida and had no issues. This week, we had a chilly night and in the morning I ran the rear furnace for a few minutes to take the chill off. When the furnace shut off, it made a squealing sound, as if the fan was slowing down and squealing until it stopped.

When I tried to turn it on again, there was nothing. The fan did not run and the furnace did not light.

(Normal operation when furnace comes on: fan starts first then you hear the flame come on. When it reaches temperature, furnace and fan shut down.)

I took both the interior and exterior covers off looking for something (don't know what), but saw nothing unusual. The thermostat works, since most of the days have been pretty warm and the AC is cycling properly.

Is there something I should be looking for? Breaker/fuse?

My thinking is a fan issue. I'm assuming if the fan does not run, the furnace will not light. Am I right?

Thanks.

[Chuck v]

Rider,

It could be the sail switch or the fan motor itself, or even the blade binding up. There has to be air flow detected by the sail switch for the lighting cycle to complete. You probably have a Suburban furnace like I do in my Tour Master -- most models are covered in the on-line manual you can find here: http://www.bdub.net/manuals/Suburban_Service_Manual.pdf

There is a pretty good troubleshooting section in this 40 page manual...let us know what you find and if you need additional things to look for.

Chuck

[GulfStream1]

I would guess that the fan motor bearings dried up and froze. Check the electric motor, I bet it is frozen.

[03heritagerider]

Sorry it took so long for the follow up.

Had an RV tech that works here in the park take a look. He also thought it was the motor bearings, so he ordered me a new motor. When it arrived he pulled the motor and noticed the squirrel cage (fan blades) had actually melted to the side of the housing. He suspected it was caused by friction of the blades but could not determine the cause.

Anyway, since the motor seemed to be O.K., he replaced the squirrel cage and all was good. ($80.00 total bill) Since it was replaced, the weather warmed up and the furnace was only used once.

[RayChez1]

Did you replace the motor? I suspect that the bearings on the motor were worn and was allowing the fan to make contact. Sloppy play on the motor bearings cause the fan to make contact with the cage and that was the squealing you heard.

I think I would have changed the motor since you had purchased it already because if there is any play on the shaft, you are going to have the same problem all over again. There had to be a reason why that fan melted.

[03heritagerider]

No, we didn't replace the motor. The tech pulled it and checked it out. He said it was in balance and spun freely once the fan was separated from it. The only guess he had was a fan blade may have failed causing the imbalance. The imbalance then caused the friction.