Easy fix of my screeching furnace motor - Bad connections!

[Not_a_Yurt_]

A summary for you who don't want to read the gory details -- Clean up your electrical connections. Low voltage due to bad connections can lead to problems that are easily avoided by maintaining good electrical connections.

For those of you who want the long story, here goes:

I bought a used 1999 Winnebago from a private seller at a great price. All was well. Until last week, far from home, the furnace's squirrel cage fan motor started making a horrible screeching sound. Maybe the bearings needed lubrication? Opening up the panel, I saw that the motor has sealed bearings. But, optimist that I am, I sprayed lithium-based motorcycle chain grease on whatever looked like it might penetrate to the bearings. No difference.

I called the friendly on-site RV repairman who showed up on time. and was knowledgeable to boot. He told me that this problem can occur when the motor's bearings are shot (not likely, in his opinion), have some grit in them (again, not likely) or when the motor receives a low voltage current for some reason.

I told him that we were hooked up to shore power when this started, so, the low voltage hypothesis was unlikely.

He just rubbed his chin and then set about checking the wiring connections--jiggling here, unplugging and re-plugging there.

Well, bad connections, developed over the years since 1999, in a coach that sat for far too long without use by the previous owner caused the problem. Who would have thought wires that worked for weeks would start having problems?

With the electrical connections cleaned up, the furnace works just like advertised, and all is well. DW is happy, and I cheerfully paid the service charge without having to spring for parts and labor. (And friendly RV repairman even gave me a break on the service charge.)

So, my free advice is that I recommend you check and clean up electrical connections before you call the friendly on-site RV repairman to come look at your rig. Especially those connections under or outside the living area of the coach. I now know that low voltage caused by bad connections on the 12 volt systems just may be a problem you can fix yourself. And friendly RV repairman can then stay home.

My 2 cents, based on experience.

[bob_b1]

My screeching sound was created by the plastic squirrel-cage fan rubbing up against the plastic cover. My fix was to create a really thick gasket (4-gaskets one on top of each other) so that the cover would stay away from the fan. It works great.

[Carm]

I had my furnace motor start squealing while on the road in 2010 and did a roadside repair: as others have noted, a bit of light oil in the motor bushings fixed it. I removed the furnace and dis-assembled the motor/fan assembly in a parking lot with no more than basic tools. The hardest part was pulling the squirrel-cage fans off the shafts on each end of the motor and then getting the fan housings apart to get at the motor bushings: everything was stuck because it had never been taken apart.

Now I oil the bushings every Spring as part of my pre-season maintenance. Everything comes apart easy becasue I do it every year, and I can have the furnace out, bushings oiled, and furnace re-installed in about an hour: it's quite basic.

[vector]

Had the same screeching situation. The noise would subside after a while but it kept getting longer before it would quiet down. Test the fan motor by pulling the red positive lead from the relay and the black ground wire as well. Connect these leads to a 12V source and see what gives. Try the oil fix if you can get to the shaft bearings. They are pretty well buried. I bought a fresh motor from an eBay vendor and replaced old (13 yrs) screechy. All is quiet now. FWIW, I really doubt the electrical connection explanation would cause the motor noise.

[wolfe10]

Sewing machine oil is inexpensive and works well. But any light-viscosity non-detergent oil will work.

[Not_a_Yurt_]

Thanks, Argosy24, and Wolfe10, too. Light oil is the next attempt to remedy the screeching. I'll post an update if there is more to this story. Happy New Year to all who haunt this forum!
Warm regards,
Chris (Notayurt)

[dougrainer]

I appreciate your posting the update. But, the fact remains that the so called RV Tech was ripping you off by stating that loose connections caused a motor type squeal. He should have replaced the motor---Period. Doug

[Argosy24]

Try some light oil as Wolfe10 said. Lithium would be pretty slow to penetrate and what did wouldn't last long. But as it helped the bushings are probably good, just dry, and light oil will solve the problem.

[Not_a_Yurt_]

It turns out that the RV Gods are indeed laughing and testing me. The screeching furnace motor is back, intermittently, with no discernible common cause. So, it seems that the bushings are the problem. Perhaps from disuse? I don't know. Thanks again for your replies and comments.

[Not_a_Yurt_]

I much appreciate your replies and comments. I don't know how or why the furnace fan motor decided to send out its call for attention, but it's working as I write this.

Maybe the grease I applied did indeed penetrate, or maybe the RV Gods just needed a laugh at my expense. Or, maybe owning an RV means that we're all just part of some karma-influenced economic stimulus program for each town where we set up camp?

Well, we'll leave a few bucks at each stop, be happy to do it, and appreciate our freedom and our ability to take the road where it takes us. So many folks don't have the means to join in. We're grateful for our ability to share in this experience with all of you!

I'm liking this RV feeling. DW and I decided to stay another three days at our current site. Hey, what's the hurry?

[jhilley]

dougrainer wrote:
Sorry, but LOOSE/corroded electrical connections will not cause a Motor to screech or make noise. The odds are the lithium you sprayed finally penetrated the shaft to the bushings and while the RV tech was there finally stopped the noise. Doug

I agree with this. I can see one situation though where maybe it is the electrical connection. That is if it can never get up to speed.

[Jagtech]

So, how many of us lube the bearings in our furnace motors BEFORE they fail? Maybe its time....

[John_Joey]

I seem to always find myself with older RV's. I think I just enjoy working on them. With that said, I'm guessing that about 80-90% of the problems that I fixed was caused by corrosion from sitting too long without use.

Amazing what a little sandpaper and the right type of lubricant can fix on an RV.

[rocmoc]

My screeching fan motor required replacement. We were staying in the MH while on a trip so the repair location allowed us to remain in the MH while the repairs were completed. When the motor was pulled you could easily see the worn out bushing had even started to wear into the frame. Always ask for your parts during any repair. It is your right to receive the replaced parts.

rocmoc n AZ/Mexico

[dougrainer]

Sorry, but LOOSE/corroded electrical connections will not cause a Motor to screech or make noise. The odds are the lithium you sprayed finally penetrated the shaft to the bushings and while the RV tech was there finally stopped the noise. Doug