Community Forums

chindog · 09-26-2022, 08:06 PM

Our Coleman Mach 3 heat pump A/C has started making a high pitched whining noise (or maybe it could be called a one note whistle). The A/C and heat pump features are working fine, but it does make an annoying sound, and the neighbors are complaining. I'm thinking it's probably the bearings on the fan motor going bad. Does this sound like a motor replacement would fix the problem?

MrMark52 · 09-27-2022, 05:59 AM

Yes, if it is the fan motor bearings. But it could also be something vibrating against something else inside the unit or dry rubber compressor isolators.

FWIW - you can re-lubricate the fan motor bearings and save yourself some $’s and maybe some time if your mechanically capable (or at least as mechanically capable as it takes to remove/replace the fan motor).

Remove the fan motor
Clean shaft using a little WD40 on a rage as a cleaner
Remove the 4 thru bolts of the motor.
Carefully lift the motor so as to point one of the shaft ends downward and thump that end on your workbench
Slide one of the end bells away from the motor stator so you can see the inside of the bearing cup inside of the motor end bell
Take some light weight machine oil (3-in-1) and saturate the bearing cup where the shaft goes thru the end bell
Allow a few minutes for the oil to pool in the bearing cup
Sop up any excess oil with a paper towel.
Flip the motor end for end, follow the same procedure as above for saturating the bearing reservoir
Slide the end caps back to the motor, noting where the thru holes are in the stator for where the long bolts go from motor end caps and the stator.
Reinstall the nuts and tighten lightly
Try to turn the motor shaft - if it seems tight, give a few light raps to both ends caps with the end of your nut driver
Tighten the thru-bolt nuts once fully
Check for smooth rotation of the shaft once again - if it seems tight, try a few raps on the end caps again or loosen the nuts and follow the process once again.
Reinstall the motor back into the unit.

153stars · 09-27-2022, 06:08 AM

Some owners report fan rubber isolator mounts collapsing and fan rubbing. Mine the sheet metal buckled downward under motor just a bit and I shimmed up to clearance the fan blade.

chindog · 09-27-2022, 08:07 PM

Thanks guys. I'll take a look at this before I order a new motor.

DancinCampers · 09-28-2022, 07:41 AM

I have a Coleman 4900 series heatpump and changing out the motor got rid of the high pitched bearing noise. The motor has sealed bearings. I have replacement bearings but have not found a shop yet to press them on. I tried to remove the metal seal on the bearings but could not without damaging them. I hope to have the bearings pressed on so I can replace in the front unit.
My motor is mounted vertically, and there is a foam seal required where the shaft goes into the mounting plate. These are cheap from AirXcel but shipping is not, so I included a condensate pump in the order.
I got my replacement motor on Amazon, which did not come with the seal.

nvs4602 · 09-28-2022, 07:56 AM

My brother has a 2015 Winnebago Tour with 3 of the same air conditioner units. The fan blades on 2 of them flew apart, and had cracked mounts. He had new blades and mounts put on all 3 units. Cost him a little over $1300.00 to have done.

MrMark52 · 09-28-2022, 09:57 AM

Quote:

Originally Posted by DancinCampers

I have a Coleman 4900 series heatpump and changing out the motor got rid of the high pitched bearing noise. The motor has sealed bearings. I have replacement bearings but have not found a shop yet to press them on. I tried to remove the metal seal on the bearings but could not without damaging them. I hope to have the bearings pressed on so I can replace in the front unit.
My motor is mounted vertically, and there is a foam seal required where the shaft goes into the mounting plate. These are cheap from AirXcel but shipping is not, so I included a condensate pump in the order.
I got my replacement motor on Amazon, which did not come with the seal.

To be sure I took a look at the motor used in the 49000 Series of HP units by Carrier/AirXcel - it’s rare to see a FHP motor of this type to be built with ball bearings. May be because it’s mounted vertically, but that’s hard on ball bearings (weight of the rotor plus the evaporator blower wheel and both the weight and thrust load of the condenser fan).
Quite often it’s advertised on motors such as these “sealed for life” bearings, and the bearings are sleeve bearings. They’re lubed for life because oil ports were not included in the end bells. They can be lubricated following the instructions given above.
Or, by placing the motor on end, cleaning the shaft as it enters the end bell, and saturating the gap between the shaft and end bell with machine oil. Once it will take no more oil, flip the motor over end for end, and do the same to the other shaft.
If of course this motor truly has ball bearings and they are already squealing, then lubrication being added in the above ways is a short term solution.
If you have ball bearings and get the motor apart, you can use a Dremel tool to cut the old bearings off. Clean the bearing race surfaces up of any dirt or Dremel shavings and put the rotor in either freezer or refrigerator, put the new bearing in a warmed place of not more than 150-160 degrees or so for about 10 minutes (you don’t want to cook the grease out of the bearing).
When ready, remove the rotor from the cooler and the bearing from the warm place - it should easily slide onto the rotor. It may require a few easy taps with a hammer using a piece of pipe to slide over the shaft to apply for pace against the inner shaft of the bearing.

computerguy · 09-04-2023, 08:32 AM

I have the same AC units in my '16 Bounder. Actually my documentation says one is a 3 and the other a 15. These are the unit numbers I have written down from when I bought it 48058-969 and 48064-969.
I have lived in my unit full time since '17 so the units get a lot of use. Mine are also heat pumps. One is 15k BTUs and the other 13.5.
The 13.5 was acting up few years ago but I actually vacuumed out the fins from the inside as I saw some dirt/dust accumulating. I thought nothing more as it seemed to fix it. I think I also cleaned the internal fan a bit too.
Now the 15k unit is doing the same thing. I tried the cleaning piece but no luck. I noticed the inside fan had a bit of a wobble to it also and thought that might be it. Not sure of the 13.5 had the same issue. I replaced the internal squirrel cage now on the 15k unit but that did not seem to fix it.
It is not all the time it does it so kinda hard to diagnose. If I had to guess it seems it is doing it more often during high humidity days.
A little research says it might be a motor bearing. Not sure this is it because the noise sure seems like it is coming from the squirrel cage itself.
Others say it might be one of the capacitors.
More talk about it actually rubbing on something. I am pretty sure this is not is.
Any thoughts from first hand experience with this, what seems common, issue?