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Not to be stupid or anything but we're supposed to know what an SF-25 is??

Steve and Joy

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Please be complete and specific . You are asking folks to solve a riddle with absolutely no clues .

An SF-25 , in this forum , is likely a Suburban Furnace model SF-25 .

Here's a manual to help you figure out what is making the noise .Probably the fan motor needs replacing .


Goes around , comes around .

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Welcome to the Escapee forums! Most of us are friendly and will happily help you in any way that we are able. 

13 hours ago, Pat & Pete said:

An SF-25 , in this forum , is likely a Suburban Furnace model SF-25 .

I suspect that Pete is correct about this being a furnace question and if so, the most common cause of a squealing furnace if it has not been used in some time is for mud dauber hornets to have built nests inside of the blower wheel.  When they do that it will through the wheel so far out of palance that it makes an awful sound, probably the worst noise that I have ever heard a furnace make. For some reason the odor from propane tends to attract bugs and they love to build nests in the combustion chamber. I have had that experience and it sure got my attention.

If that is the problem, you will probably need to pull the blower out to remove the nest. On the other hand, if this isn't a furnace problem, please let us know and with more information we will try again. 

Edited by Kirk W
repair a typo

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure



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  Lets say it is a suburban sf 25 furnace. So there are two basic noises that could be coming from the unit.

  First would be a bearing problem on the motor shaft. They tend to come on slowly. Very faint as in hardly detectable at first. To really screeching noise.

  The second noise could be that the combustion wheel has slid on the motor shaft. And then it is rubbing the blower case. Sorta a different kind of noise. I have seen that noise be more of a chirping type sound.


  Now thinking about it there could be another noise that say started all at once.   Probably a bees nest. But that would take a few days to build. Then it makes an out of balance noise.


  One time I was working on a generator for a customer and got it working properly. Next morning he called and said his furnace started to make a really bad noise in the middle of the night. He turned it off as it was not really freezing that night.  So I took the furnace cover off and was looking at what might be the problem. Dead mouse in the blower wheel. Apparently it was in the wheel when the furnace came on.


   Vern in a T-shirt 

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Aj, FWIW I agree with Vern's great advice above, if you're talking about your furnace, over 49 years of RV ownership UNFORTUNATELY Ive heard such a bone chilling high pitch squealing and it was caused by my furnace blower motor bushings, it got worse when it was cold and needed the most, and seldom cured itself. If that is the problem ???????? they are readily available at a reasonable price but swapping them out and the squirrel cage blower can be tricky. Orrrrrrrrrrrrr maybe you will luck out and its crud or mice or insects got in there ??? Look for simple fixes first...follow Verns advice !!!!!!!!!!

Merry CHRISTmas

 John T Live in the RV near sunny Sebring Florida 

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