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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7498
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Ive got a rheem silhouette ii furnace/ac system. The fan

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I've got a rheem silhouette ii furnace/ac system. The fan is not running/or running at low speeds. Actually I have two identical systems. I've interchanged the capacitors to verify that is not the problem. The squirrel cage spins freely. I was even able to spin it and then quickly turn on the power and the fan started up. But it still runs below the normal running speed and puts out very little air.

Backing up a bit, the system was working fine until this afternoon. When I first looked at the unit - in the attic...I found that the overflow drip pan was full of water. I then found that one of the labels from the condenser had fallen off and was blocking the drain tube. I cleared that thinking that may have tripped an overflow switch or something. At that point when i restored power, the unit just hummed. Then I went through the above. Perhaps it was just a coincidence.

At any rate, do you think the problem is the blower motor? Is there any way to test to be sure, before I replace that.


gurutech67 :

Hello Brian this is Scott, is the other furnace functioning normally?


Hey Scott - yes the other system is fully functional

gurutech67 :

is there any chance that the blower motor in the unit in question got wet?

gurutech67 :

Brian I seem to have issues with chat did you responde to the question did the motor get wet?


So far it sounds like you may have bumped one of the wires going to the motor, the one that comes from the run capacitor and goes to the that the motor will run when you push it, but not to full speed.

It is unlikely that the motor failed just because you opened up the service panel to clean the drain.

Spend some time carefully looking that over.... we can go from there. I will be in for another half hour this evening, then back in the morning to pick up your question of i miss you tonight.

We keep going until we get this resolved.


Customer: replied 3 years ago.

Hey Phil -


Thanks. Interesting you raise the point of the wire connections to the capacitor.


As I was switching out the capacitor yesterday it looked like one of the wires was a bit frayed between the wire and the spade connector.


I went back up to the attic this morning to look at it. It did seem like a weak connection. I didn't have another spade connector on hand, so I just cut off the connector stripped the wire and threaded through one of the eye holes on the capacitor. When I first powered up the fan came right on, but did not hit full speed. I powered down and tried to tighten the wire connection. Second time I powered up the fan did not start. Powered down, gave the fan a spin and powered up. The fan started but again did not hit speed. I'll run out this am and get a spade connector.


Naturally, we're having the hottest weather of the summer this year - Mid-Atlantic area between Balto and DC. So if I need a new motor, I'd want to order as quickly as possible. Based on what I've described, do you think it is unlikely the motor has failed? Given it spins freely and runs?

Hello again, the chances are about 50% that the fan motor might be good, and that the capacitor or the wire connection to the fan side of the capacitor is bad.

If the wire was good and not burnt, only frayed, it would not have been a problem... if it was frayed so badly that there was little or no electrical connection, then the wire could have been the problem.

As motor bearings wear, the rotor of the motor begins to touch the stator inside the motor and the motor will not run unless you push it... these motors last between 7 and 8 years before they wear out the bearings.

You need a good wire crimp tool to crimp the wire to the 1/4" female spade connector.

Let me know, we can go from there.

Customer: replied 3 years ago.

Ok - thanks. I'll be working the wire later this morning and let you know.


BTW - the motor/system is about 15 yrs old. If that is a factor in your assessment.

Hello again, at 15 years old the motor bearings are no doubt warn enough that the rotor is touching ever so slightly on the stator inside the motor...and that will cause this problem.

If you can feel any slight up and down play on the motor shaft, the bearings are worn and that is most likely the problem.

Customer: replied 3 years ago.

Sounds like I couldn't go wrong replacing the blower motor - even if it just ends up as a wire issue at this time? Any suggestions for determining the specific motor - without removing the motor?


I've got the manual - the unit is a Ruud UGDG or UGDJ. I replaced the motor in my other unit and have a note that it was a 3/4 horsepower motor - but I don't see any other notes on it.

Hello again,

Here is a *wholesale Ruud parts source... you might try applying for an account and see if they will sell to you... they will need the full model number of your furnace..UGDG and all the numbers following it. CLICK HERE

IF that fails contact these people with the full model number
shop for price at

and at

Call them on the phone, no need to try and navigate their web pages

I will put up the ratings box now so you can rate my work. If you rate *positively I hold the question open for unlimited help as move forward fixing the furnace.



Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7498
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
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