7655-856 Motor Problem

[Joe]

Hi folks. First I'd like to say thank you for providing such a valuable resource. This is a fantastic website.

I have done some searching in previous posts, but have not yet found the exact answer to my question, so I'm hoping you can help me out.

I have a Coleman model 7655-856 furnace. This morning when I got up and turned up the heat the furnace started up as normal. After an hour or so I turned the t-stat down because it was plenty warm. A while later my wife got up and thought it was chilly so I turned the heat back up. The burner fired up normally but after the 1 or 2 minutes of pre-heating, the blower motor did not cycle on as it should. It sounded like a humming noise coming from the motor. I turned the t-stat back down and still heard the humming noise for a while, then it stopped.

After waiting a while I tried again. Still no go. The blower motor is not turning. So, I did a little trouble shooting. When I manually turn the fan with my hand it does not continue to rotate freely. It seems to have some friction and it feels like there is one particular point in the rotation that is "stickier" than the rest. After trying to get it to start there is some heat built up on the motor, but I'm not sure if that is from the motor itself or from the rising heat from the burner.

During another test I saw that the blower was trying to turn, but it was turning very, very slowly. I tried giving it a little help by turning the blower with my finger, and it went a little faster but not as fast as normal. Now it won't even do that. It turns really, slow and when I try to help it with my finger, it won't pick up any speed.

I'm thinking that the motor is bad. What do you guys think? If the motor is bad, how difficult will it be to replace it. I'm somewhat mechanically inclined but I'm certainly not an electrician. I am willing to replace it myself if you think this is something I can do by myself.

Thanks in advance for any advice you can offer.

Joe

[Robert]

Hi Joe,


Is it heat & a/c or just heat only blower ?


Fairly easy to replace, this article will help with that:

http://www.mobilehomerepair.com/article ... lower.html



Trace the motor speed wires back (should be Lo or Med. Lo).

Make sure it is getting full 120VAC to it. Also, is a manually lubricated motor ?

If so, has it been oiled ?



Thanks,
Robert

[Joe]

Good morning Robert. Thanks for replying!

It's a heat only unit. I'm pretty sure there are no motor speed wires. It is either on or off . . . no option for speed control.

When we first bought this place 5 years ago (it's used - about 30 years old) I looked at the motor and did not see any place to oil it. I looked carefully again yesterday and still do not see any place to oil it. I'm pretty sure it has sealed bearings.

It also appears to have what I believe is a capacitor mounted on the side of the blower housing.

Like I said, the home is about 30 years old and I suspect that the blower motor is the original.

Thanks

Joe

[Joe]

Robert - One more thing I just thought of.

Don't know if it is related or not, but the night before the heater went down, I heard some periodic clicking sounds coming from the area of the furnace. At first I thought it was the normal sound of the furnace getting ready to shut down once the thermostat temperature was reached. But as I recall, I heard the clicking sounds even when the furnace continued to run.

Any ideas what that may have been and if it is related?

[Robert]

Fan Switch # 7975-3281 on left side of page:


http://www.mobilehomerepair.com/ColemanGas.html


Maybe the fan switch is opening/closing.


Even if there is only one speed, that is the speed wires.


Make sure that on a call for heat, the blower motor is getting full 120VAC to motor.


IF you have full 120VAC at connection to motor wires, then ohm the two wires for continuity.

If it also has continuity, replace the run capacitor.



With full 120VAC, continuity through the two wires and a new run cap, if motor does not run, replace it.


If it is a bad run cap, you're covered and if not and it's the motor, you must replace with new run cap with a motor replacement.



Thanks,
Robert