Furnace squeal

[Skater]

I have a '91 B190 I bought last summer. I'm having a problem with the furnace: when it starts up, there's a nasty squealing noise for a few minutes, then it'll go away. The furnace works fine otherwise (sometimes the squeal will return for a moment while it's running).

Here's the issue: I'm living out of the B190 full-time at the moment, and will be doing so for another week, and temperatures are getting into the 30s F at night. I went without heat last night, but I'd rather not do it again.

I did a search and found a couple threads but the only one that specifically mentioned this noise involved a motor replacement that may or may not have fixed the problem.

Since the furnace is right under the couch in the 190, I'm hoping I can simply unbolt the couch and remove it to work on the furnace without having to remove it entirely.

I'm guessing the problem is either the bearings on the motor or the fan hitting its shroud. Does anyone have any thoughts or tips? I hate to call this an emergency, but it's a pretty serious problem that I need to at least temporarily fix. (I'm only staying in the motorhome for another 7 days, after which I'll be in my new house and can work on this at my leisure.)

Thanks.
--RJ

P.S. Note - I do have a heat strip, but it doesn't work that well. Also, I can borrow a friend's electric space heater, but my experience with them in the camper is that they don't work very well, either (the confined but relatively drafty spaces seem to mess with the thermostats). I really want the furnace working correctly... Thanks!

[InsideOut]

I would start with taking it apart and cleaning everything. A build-up of "gunk" could be causing the motor to labor on intial start-up. You may then also be able to see if a new motor is a viable fix.

If the cleaning works, your home free. If not and you do need a new motor, I would invest in one of two things either an inexpensive ceramic heater (assuming you have electric hook-ups) or a good set of earplugs to get you through the next couple of nights.

Shari

[norbert]

hi rj,
id check to see if the squirrel cage is loose on the shaft...if so reseting and adjusting should do it. i believe that most likely is your problem
norby

[Happycampers]

RJ. Same thing happened to us about a month ago on our 5th wheel, if I went outside and hit the side of the trailer near the exaust it would quit squeeking, after a few times of that I took it out and the fan motor bearings were going bad and replaced the motor. $106.00 later it works great. It would only make this noise at start up. Hope this helps.

[Skater]

Hitting it doesn't help the squeaking. When I hit it, it stops squeaking for a only for very brief moment - which gives evidence to the squirrel cage misalignment theory, I hope.

[Skater]

Hey, everyone - the squeal woke me up several times one night, so I went the following night without heat at all (yeah, it got kind of cold). I called a service guy who came out to the camper, pulled the unit, and replaced the motor (and cleaned the furnace). Works GREAT now - I can barely even hear it running. Thanks for the advice and suggestions - your comments helped me understand what to expect when the bill arrived.

Funny story: When we put it back in and tested it, it initially wouldn't stay lit - it would spark then shut right down. After a few minutes of both of us scratching our heads, I went out to make sure I had actually turned on the gas, and I noticed that the tape he'd put over the exhaust while the furnace was out was still in place. I pulled off the tape and it fired right up. We had to laugh.

[InsideOut]

Glad to hear you are warm & toasty in your toaster once again!

Shari

[lewster]

Originally Posted by Skater

Hey, everyone - the squeal woke me up several times one night, so I went the following night without heat at all (yeah, it got kind of cold). I called a service guy who came out to the camper, pulled the unit, and replaced the motor (and cleaned the furnace). Works GREAT now - I can barely even hear it running. Thanks for the advice and suggestions - your comments helped me understand what to expect when the bill arrived.

Funny story: When we put it back in and tested it, it initially wouldn't stay lit - it would spark then shut right down. After a few minutes of both of us scratching our heads, I went out to make sure I had actually turned on the gas, and I noticed that the tape he'd put over the exhaust while the furnace was out was still in place. I pulled off the tape and it fired right up. We had to laugh.

That IS a good one. They don't work too well when the exhaust path is blocked. At least now you know that the ECO (high temp limit switch)on the furnace is working .

[Skater]

Hi. Time to dredge up an old thread. Unfortunately the problem is back, which is rather frustrating. I'm thinking it's time to replace the motor (again) and both fan blades - I'm just tired of dealing with it. Anyone have any more thoughts on this?

I've played with it on several occasions. There's a metal clip on the one set of blades, which I believe is intended to be a counterweight. I'm not sure if the problem is that the clip is loose or what. My theory is that one or both of the blades is off balance, which kills the bearings on the motor...

[Skater]

Another update on this: I bought a new motor and a new combustion blade; the squirrel cage blade was no longer available for sale.

The motor I pulled out may have been the original motor - I'm not sure if the guy replaced it or not. He told me he did, but there was some rust on the shaft that didn't look to me like it'd be just a few years old. Also, I had to bend the metal combustion blades to get the set screw loose...which makes me wonder how he would've been able to do it. I managed to break an allen wrench off in the set screw while trying to loosen it!

The new combustion blades are actually plastic. I put them in with the new motor and it's running quiet again! Hopefully it stays that way this time. Part of me hopes that the guy didn't actually replace the motor the first time, because then that means this should fix it ... but it would also mean that he lied to me, which doesn't make me very happy. I suspect he took it apart in his warm shop, cleaned it, put it back together and found the squealing gone (which makes sense because it didn't squeal when it was warm), and called it good.

Thanks again for the help. I hope this is the last time I ever have to update this thread.

[joecolao]

I have a 1992 34' Excella and my furnace is starting to squeal from time to time, usually on start up and rarely while running. My buddy has the same rig as we do except his is a 1993. He has the squealing issue for about a year. The difference between the two of us is that we are Full Timers.

Anyway, I appreciate the thread and all the contributors and at least feel up to the challenge that seems to be ahead of me. The only question I have is the Skater, it seems that you replaced the motor - what went wrong after less than 3 years? Was it the squirrel cages that perhaps should have been replaced when you did the motor? Are the plastic squirrel cages better than the metal?

[AirHeadsRus]

Hi Joe,
I just replaced my fan motor in my NT 30 furnace last week. Wasn't to bad of a job once I figured out how to get everything out. If you need help, send me a PM or I'll be watching this thread. I think the place I got my motor from had the metal squirrel cages as well.
regards,
Joe

[Inland RV Center, In]

The squeal noise from the furnaces, is some what common.

It's caused by the bearings in the motor becoming "'dry".

If your handy, you can disassemble the motor and lube the bearings, several times, so that the oil can soak in.

Andy

[JimW]

I, too, had a squealing Atwood furnace motor last October, while in Moab. The squeal was so loud I thought we'd wake the neighbors! The temps were in the low 30's so the furnace was cycling pretty often. Kept me awake. The nearest motor was in Durango, CO.

http://www.airforums.com/forums/f313...per-70157.html

This link helped me replace the motor. This motor comes as a kit with new mounting brackets and a metal piece that keeps the motor from coming out of the bracket. New blower wheels probably are unnecessary. I did put a mat on the ground under the heater to catch dropped screws and was glad I did. The project took about two beers to complete.

The new motor seemed noticeably quieter than the squealer before it started squealing.

[Jammer]

DC blower motors usually do fail due to bearing failure caused by seal failure and loss of lubrication.

When a replacement motor is unavailable or excessively costly it is possible to disassemble the motor and lubricate the bearings. I have done this several times on cars, trucks, and ag equipment, though never on a furnace. My experience has been that it doesn't always help (sometimes the bearings are too far gone for lubrication to help), and at best it's a fix that will last a few years. After all, it's the seal failure that led to the problem in the first place, and squirting some oil in there doesn't do anything to fix that.

I had a planter (for corn) that had individual electric blowers for each row to provide air for the metering system. I ended up drilling holes on the outside of the motors so I could drizzle in some oil every year. It worked out OK but then the motors were easily accessible.

I'm guessing Skater's rv tech may have re-oiled the bearings for similar reasons. It can be nearly impossible to remove a badly rusted blower wheel without damaging it and without a replacement wheel in hand it would be tempting to take shortcuts.