Furnace Squirrel Cage Shredded to Pieces

[Maddog55]

2019 Reflection 297RSTS.

We turned on the heater and it ran fine for about 10 minutes before it started squealing and making a screeching noise. After squealing for another 10 minutes, the squirrel cage blew apart making a huge racket of plastic blades getting chopped to pieces. We've had the travel trailer for about 2 years and travel full time. But we don't use the furnace all that much. About the only time we use it is when the overnight lows are expected to be below 32 degrees and then we'll keep it at about 45-50 degrees. For the most part we follow the warm weather south so we don't use the furnace all that much.

Grand Design would not help with repairs or warranty because it was out of warranty one month before the incident.

Ordered a replacement metal alloy squirrel cage part# 350129-001 and replaced it in lieu of the broken plastic squirrel cage.
There is an outside access panel to gain access to the squirrel cage in the furnace.
There is a circuit board on top of the squirrel cage that needs to be removed to install the new squirrel cage.

$170.00 for service tech to come out to troubleshoot and clean out the plastic pieces from inside the furnace.
$30.00 for metal alloy replacement squirrel cage.

Once I watched the technician gain access to the furnace, I realized that I could order the replacement part and install it myself. So that's what I did.

Feel more confident with the metal alloy squirrel cage. Understand plastic is much lighter than metal alloy. It seems the heat softened up the plastic and caused it to expand and rub against the squirrel cage enclosure (I think / not sure what caused it to get shredded). But I'm afraid the fan motor may carry additional load/amperage and result in future motor failure. Will report back if there are any follow on issues with the fan motor.

For now it's working fine and I'm cautiously optimistic that it will run without any future issues.

[D2Reid]

Good write up, thanks for sharing. I have been down that road a couple of times.

[ckreef]

Good post.

[Redapple63]

Very nice writeup, I will also bet the weight difference is negligible, and with the considerable size difference it is capable of moving much more air.

[geotex1]

Very nice writeup, I will also bet the weight difference is negligible, and with the considerable size difference it is capable of moving much more air.

No difference in size. The plastic one in the picture comparing the two it is half-lost!

I didn't even realize Suburban had tried to go to plastic again... They had a miserable time with plastic 6-7 years or so ago.

Thanks for bringing this up as something to check!

[Maddog55]

No difference in size. The plastic one in the picture comparing the two it is half-lost!

Correct. The original plastic squirrel cage was the same size as the metal replacement.

On a separate note, the set screw on the original plastic squirrel cage may have been loose causing the squirrel cage to lift up and rub against the top of the housing cover. Just a guess as I'm not sure exactly what happened that destroyed the upper portion of the squirrel cage.

As noted on the original post, it took about 10 minutes of running the furnace without any squealing and then 10 minutes of squealing before it blew up. In hindsight if anyone experiences the squealing sound, it might be worthwhile to remove the squirrel cage housing cover from the outside access panel to check the upper and lower clearance limits of the squirrel cage. The set screw allows for a squirrel cage float so that it can be adjusted up or down on the electric motor spindle.

I didn't see any other forum members addressing this issue, so it may be an isolated incident.

[Redapple63]

No difference in size. The plastic one in the picture comparing the two it is half-lost!

I didn't even realize Suburban had tried to go to plastic again... They had a miserable time with plastic 6-7 years or so ago.

Thanks for bringing this up as something to check!

Thanks, I went back and looked at the pictures more closely and I now see where it shattered.

[ckreef]

My guess would be either the set screw came loose causing the squirrel cage to sit at a slight angle on the spindle or the motor mounting bolts loosened up a bit. Did you check to make sure the motor was firmly mounted when you put it back together?

I know hindsight is 20/20 but anyone reading this if the squealing starts turn off the unit and inspect immediately. You might be able to catch the problem before things get ripped apart.

[Maddog55]

My guess would be either the set screw came loose causing the squirrel cage to sit at a slight angle on the spindle or the motor mounting bolts loosened up a bit. Did you check to make sure the motor was firmly mounted when you put it back together?

Yes, it appears the motor is firmly mounted. I ran the furnace for a while after installing the new squirrel cage. At least for now, it seems to be running fine. My guess is that the spindle set screw was slowly working its way loose causing the squirrel cage to slowly slip up.

Or maybe the plastic squirrel cage was a bad batch with a combination of dry rot or stress fracture accelerating plastic degradation from the heat.

The bottom portion of the squirrel cage appears to be intact. It’s just the upper section that got demolished.

[rwilliamson1760]

I wanted to add that my Dometic Furnace fan just exploded as well...after the 3rd time using it. Dometic DFMD 30111 in a 2022 Imagine 2970RL.
I disassembled the Blower Motor Assembly. Found nothing out of the ordinary. Reassembled and ran in my garage for a bit...before re installing it back in my TT. Working fine...so far.