Furnace SQUEEKING!

[thepager5]

Hey guys - finally had to fire-up the furnace. Heat works, Blower blows and all working after replacing the wall thermostat. (its a hydro flame located under the sink, at floor level - see photo)

But, there is this terrible squeeking coming from the fan compartment/blower. Is there a way to quieten this? It does seem to get a little quieter as it warms-up.

By just looking in, I can see where the blower is located but it looks difficult to reach. Any help will be appreciated!!! (i have no operator manual)

As usual - THANKS GUYS!!!

kp

86 Dolphin 21ft model 900

[Pat]

My worst guess is that you need a new blower motor. Beyond that, your guess is as good as mine. Maybe better because your there to see and hear it.

[thepager5]

Will the furnace need to be pulled out, or can the fan motor be reached while installed?

kp

[motoyhomme]

Hi KP,

Just been there with my furnace. Mine first started as a squeek, which would stop after awhile. Then it developed onto an annoying squeal which would stop after it heated up. Finally, it wouldn't stop squealing and then the motor froze up.

The furnace has to be removed from the motorhome. Mine was straight forward. Remove the exhaust on the outside, disconnect the propane line, wiring, flex hose outlets, and whatever screws that hold the unit in place. Mine is located under the sofa with a front piece under the sofa that is held in place with velcro that made it simple to remove at that point.

Upon tear down of the unit I found a 12 volt motor with a squirrel cage fan on one end and a regular 4 blade fan on the other end.

The price of the motor was around $100+. I decided at that price why would I want to put a shiny new motor into a dirty furnace, so I just bought a complete new furnace on-line. I even managed to kick it up a few thousand btu with the physical dimensions of the box remaining the same. I think I paid around $475 for a new unit. My furnace is a Suburban model.

These guys cover everything you need for repair or replacement. I even received my unit next day with no extra charges.

http://www.pplmotorhomes.com

It costs a bunch and it will cost a double bunch if you can't do any of the work yourself.

The kicker: After replacing my furnace, I decided to try free up my old motor. I put penetrating oil on both ends of the motor where the bushing are for several days. After about a week the shaft would spin with the flick of the fingers. I could have saved a bunch of money, but would the fan freeze up while I was in the Artic or somewhere?

Good luck,

Allen

PS...after going back and reading your post, yours may be easier to replace. The Atwood Hydro-Flame looks like it only has the one duct directly on the furnace front. Remove the outside duct first, then look for a way to get to your wiring and propane line to disconnect them. The unit may be mounted by screws to the front, not sure though. You probably have the 12 or 16K btu unit. Do a search for your type of furnace manual on line and you may get lucky.

[Geysergazers]

Either one of the two squirrel cages is contacting the housing or your Blower Motor is shot. Access is gained by removing the furnace from the cabinet. Manual here. Yours is an FA79 furnace.

It takes about 15Min to pull your Atwood Furnace. The gas line fitting is accessible after removing the front grill (pull outward from the bottom). There are a couple screws (maybe 4?) driven through the furnace cabinet sideways (at the front edge) into the wood cabinet framing. You will find enough slack in the wires to pull the furnace out far enough to access the wires to dissconnect them. After removal of the furnace the Blower motor can be removed by disassembling the combustion air blower compartment (right side of the furnace).

If it is the motor, replace it. While lubricating a noisy motor bushing may quiet it, the benefit is temporary, and if the bushings are worn out the brushes are as well.

As always, YMMV

Lew

[thepager5]

Hey guys, thanks for the advice. I called the previous owner and he informed me he had the camper two years and never turned on the furnace. SO, I unhooked the gas line and took the two screws out on the exhaust (outside). I then slid the furnace out until wires were able to be taken out of the wire nuts. I then dusted off the outside and began to take the screws out of both sides of the fan and motor housing. I used wd40 on both sides and then turned furncce on its side and put oil on the shaft and let it seep in. I then stood the furnace on its nose and inspected the exhaust end. I then returned to the camper to reassemble.

Upon inserting the furnace into the cabinet, I inadvertantly put it in upside down. when I realized this, I immediately took it out and reinserted it correctly. NOTE: a small pile of black exhaust/carbon dust fell out and was on the carpet. I was not sure what this ment until . . .

I started it up after full reassemble. It ran fine the first 2 times. The third time it would not fire. The fan runs fine AND QUITELY. After leaving it off for a while, I turned it back on. It fired fine and heat came out.

PROBLEM: after it had run for about 20 minutes and warmed the camper, it seemed to refire and each time it "BACKFIRED" and sparks came out the exhaust rather loudly. This happened three more times over about a 30 minute period. I then stoped the furnace and restarted. As it fired, when the flame cought there was one loud backfire and then it ran fine until I turned it off.

Am I OK turning it on? Have I caused a problem by turning it upside down? It heats fine, is it ok to use it? Have I got dust in the gas ports? GOT A REMEDY????

Also, do these furnaces neet a window open or ventilation? I do not have a CO2 detector.

Thanks for any help with this one,

kp

[motoyhomme]

KP,

I think you answered your own question about the backfiring. On an earlier camper that I had years ago, it would backfire whenever I started it. It was the piezo start type. You had to turn the pilot on and push the button and it would sound like it was exploding (scared the crap outta me each time). It turned out to be a bee that had flown into the exhaust and was lodged in the gas tube. So you probably did get some dirt,rust,soot in your gas port or it may be the flame burning off some of the loose junk in the heating chamber. It may go away by itself, or you may have to take it apart again and blow and or vacuum everything.

The warm air that exhausts into your camper is free of CO2. The flame is contained inside of a box which exhausts to the outside. The box gets hot and your fan blows clean pure air over the box and into your camper.

Lew seems to be very knowlegable with your type of furnace, he may have an answer for you as well.

That's why we come to this forum, to learn from folks who have been there already.

Allen

[thepager5]

Hey there Allen and Lew,

Thanks for the advice. I ran the furnace off and on for 2 days. We are on the edge of the ice storms just inside the Arkansas Line in Fort Smith. Temp is 39 and I set the thermostat on 50 and just walked away from it.

I just checked and it is cycling just fine. No more "Scare the crap out of me" moments.

I guess I just got some soot over the gas ports or something like that.

Thanks again,

KP

86 Toyota Dolphin

[Geysergazers]

Sorry....I lost track of this thread. Yes, that's probably what happened (soot/rust which you dislodged by turning it upside down got on or in the burner). Since operation is now normal it should be fine. If it worries you though, you could pull the Furnace and remove the burner (it actually can be removed without pulling the furnace), turn the furnace on end and blow it out (through the burner hole and out the exhaust) thoroughly with high pressure compressed air. Alternatively you can remove the burner without pulling the furnace and clean it, then vacuum the combustion chamber through the burner hole. If removing the burner I would be sure to have a new OEM gasket on hand (at 21Yrs age the old one will probably disintegrate).

Ms Dolphin got a shiny new Atwood 7916II Furnace for Christmas. Boy is she happy. Her old Furnace had a slight propane leak from the electric gas valve and the blower motor was pretty loose so rather than spend $200 on those parts I bought a new Furnace on EBay for $320 w/shipping.

Lew

[Gulfstream Greg]

This may help anyone in the future. I think the bearings are whats called brass oilite bearings. They are a porous granular mixture compressed into a bearing form. The oil is impregnated into the granules during manufacture. As the motor shaft spins it creates friction and the oil will flow towards the heat source. Over the years these granules loose their oil. The first signs are a squeal at first then running quiet. As far as I know the bearings can never be restored to new as far as the oil is concerned. Even soaking them in a pool of oil for weeks will not impregnate the oil into the granules. It will help for awhile but soon the squeak will be back. Some electric motor shops have replacement bearings. Bad thing about just replacing the bearings is that the motor shaft usually has wear so its best to replace the motor with a new one. Ours (vintage 1986) squeals when it first starts then is quiet for the rest of the night. You know how the story will end.

[aws910]

Success on mine! It used to squeak all night, so bad that we would rather be cold.

Removed the grate, unscrewed the unit from the wall, disconnected the gas line (after turning the propane off lol), then had to disconnect 3 sets of wires - lucky for me, the wires had already been cut, so it was just a matter of unscrewing the twist-on connectors.

At this point, I had to reach back and grab the unit from the bottom and do a few heave-ho's to get it out. Took it into the garage, and just started removing screws and hose clamps. Dead bees and wasp nests came out en masse! Located the fan, and sprayed wd40 into the shafts, then put it all together. Reversed all steps, installed it back into the rig, and no more squeaking!

Thanks to everyone who contributed on this thread, you saved me!

[Derek up North]

Glad to hear of your success. I hope it's relatively long lasting. I don't consider WD-40 to be the greatest lubricant.

[Gary_M]

I don't consider WD-40 to be the greatest lubricant.

As well as a fire hazard. I only use 3&1

[WME]

Hope you have the steps memorized, cause you will be doing it again WD-40 is a very poor OIL, does other things well though
I ve just soaked the bearings in Mobil 1 overnight. The bearings are called oilite bearings they are designed to soak oil into them.

If all else fails http://www.ebay.com/itm/Telco-232651-Blower-Motor-12DC-Heat-Pump-Furnace-Suburban-RV-Camper-Fan-Heater-/300951260591?pt=Motors_RV_Trailer_Camper_Parts_Accessories&hash=item461217cdaf&vxp=mtr

[Vanman]

When we got ours the motor squealed like a stuck pig. The more it got used the quieter it became and now it never makes that noise anymore. WD-40 is mainly a solvent and water displacer and the solvent part will burn but it evaporates quickly. I use a lot of it to clean things but for penatrating lubrication I use

corrosionX marine, and for dry film lube(specially locks) I like poxylube cp-200 dry film lubricant, both as hard to find as they are excellent and expensive.

john

PS wow almost forgot my other favorite ,(sold in hardware stores everywhere) made by Norvey called Zoom Spout finest all purpose turbine oil, comes in a handy plastic bottle with the extendable spout on the top.

[waiter]

WOW - If that fan motor works, thats great. The exact replacement motor runs about $120, ALSO - I suspect the original motor used a lower quality sintered bearing. As has been discussed on other threads, motors like this in your automobile last decades, yet the RV furnace one doesn't seem to approach any where near that reliability.

Someone grab one of these and see if it works in the furnace.

John Mc

88 Dolphin 4 Auto (SOLD)

[Vanman]

At that price I'd be wary, but you could buy 2 and carry as spare and still be $ ahead. When I was pricing the tail/brake LED lite package I had already got at the local auto parts store for $ 20 I found it for sale at RV stores on the internet for from $ 10 and change all the way up to $ 39!! so that range might fit the variance in that motor pricing.

john