Suburban Furnace - Fan Motor - Intake Squirrel Cage Lose

So....Last night, it was 03:00 (3AM) and we were in a deep slumber. I think I was dreaming about the perfect 5th wheel (that's never going to happen) when we were suddenly awaken by a loud shrill.

Over the night, we were expecting cooler temperatures so before we went to bed, I turned the furnace down to about 68. The RV is 4 (almost 5) years old. This is the first trouble that we have had with the furnace. So, I shut that off for the night and converted to the heat pump and fireplace. It was not all that cold and we made the rest of the 2 hours without a problem. (we're still working...I don't like that word)...

Today, I pulled the front cover and did some troubleshooting. I turned the furnace back on and went outside to see what was making the noise. It was coming from the lower parts where the Intake squirrel cage is located. It was kind of a no-brainer. It was easy to know that the set screw had probably worked lose and the squirrel cage was likely rubbing on the housing. After a delicate 15 minutes tearing into it, sure enough. That is exactly what it was. I then spent another 20 minutes moving the squirrel cage back to its proper location and reset the set-screw. It took a couple of tries. Once the first "scoring" of the motor shaft has had that screw set, it tends to track back unless you hold on tight. There is a limited amount of clearance between the housing and squirrel cage (top and bottom).

For those that have not tried this before, this is not an easy job when you don't pull the whole furnace out. I tried to do this by just removing the bottom cover. The wires to the motor are really short and this does not allow a lot of play. If you finally get the cover lose, then be careful not to let the motor shift around. If you are careful, you can reset the screw and put it all back together in relatively short order. If you are NOT careful, you will break the upper blower squirrel cage and you'll then have to remove everything to fix it right. I would recommend having a helper handy to hold that lower cover up while you set the screw.

I've attached a .pdf showing step by step what to do. After having done this, I might opt to pull the entire unit next time. In fact, I may do it later this summer and replace the cheap plastic blower with a metal blower. The lower intake blower is metal. The upper one is not. Both are driven from the same motor.

I hope this one makes sense...

I've thrown in a few parts prices for the curious.

Thanks for the thorough write up Greg.

Yes, those furnaces are "fun" to work on.

Our Neighbour's Redwood lost the main board on the furnace and I helped him. I've lost a main board on ours and the tech was able to replace it without pulling out the furnace but he had to extend one of the wires to do so. My neighbour had to pull out the furnace and it wasn't easy, the most difficult part was to disconnect the heating ducts (on a manifold) from the rear of the furnace, he had to open the basement and go in and do some "gymnastics" to get to the screws that hold the manifold on! All the water lines in the way made it more complicated.

As an edit, one thing that we found is that the furnace main board must remain connected to allow the heat pump to operate, the thermostat is somehow routed electrically through the main board, even though the furnace wasn't working removing the main board deactivated the thermostat.

Well...Winter is coming...We've been inundated with rain and colder temps over the last couple of weeks. The forecast for the Texas area this winter is for milder than normal winter but wetter than normal winter. That probably includes a couple of ice storms and maybe some snow. We don't get much in the way of snow, but when we get an ice storm, it's paralyzing...

Anyway, I finally thought it was a good time to get the furnace working again. I knew the parts I needed. They were bought and delivered by Amazon.

So, if any of you need to replace the Room Blower Motor or to reset the loose Intake Fresh Air Blower set screw after it falls and awakens you in the middle of the night (you'll know what it means when it happens), hopefully this .pdf will help you resolve the problem.

It's not an easy task. It took about 6 hours total for me. I was in no hurry though...I don't get paid to work on my own stuff and I like to do it right.

Hopefully, it will help someone save a few bucks. To replace a furnace, it's about $800. If you have this repair completed, you can do the math for 8 hours of labor (including drive time) and parts markup. My required part was $37. I bought the Ignitor (just in case)...

See attached. The file is 1.5 MB. Be patient if trying to open.