Replacing the blower fan in home AC Unit

[HuntForHorns]

Last week the blower on my AC/heat pump unit up in my attic started making a rattling noise. Yesterday it wouldn't come on, just humm. I was out of town but came home today. I was able to tab on the motor a little and it came on. I thought I had at least extended its life a little. ;-) 10 minutes later it had quit.

The outside unit is working fine, just cant get the cold air circulated thru the house. How big of a job is it to change out that motor?

The unit is about 15 years old(Trane) and still uses R22. I know I will have to replace the unit soon but have been trying to limp it along.

HVAC guys let me know you thoughts.

One more question... low refrigerant wouldn't have any effect on the inside blower working properly would it?


Thanks

[DRT]

Capicitor out, bearings starting to go? Did it run smooth after you got it started?

Gary

[Death from Above]

Its not difficult. Swap it out and wait until winter to replace is what i did.

[-HIC-]

Yup not hard to test or replace. Check cap first, then move on to the motor speed wires. Look for over limit or 0 resistance, either of those will reveal a motor problem.

Refrigerant level has nothing to do with the motor operation. I guess you could argue that it would run longer with a low charge but that would just be to argue!

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[HuntForHorns]

Capicitor out, bearings starting to go? Did it run smooth after you got it started?

Gary

Thanks Gary, would it be the capacitor if I as able to tap on it and get it going?

No, it doesn't run smooth, but it runs. Why would it quit after 10 minutes?

Thanks

[deerplanter]

Not that difficult if you have good access to it. If it has a separate start/ run capacitor I would replace it also.

[DRT]

Drawing to much and over heating. Changing it isn't an overly difficult job. I've done a couple over the years.

Gary

[day0082]

Make sure you don't over size the blower when replacing the blower.

[bowhntrmatt]

I bet it’s just a bad capacitor. If it spins freely this is most likely it.

Why limp it along if you know you are in need of replacement? You won’t make back the money spent limping it along and are missing out on utility savings vs. replacing it now.

[double bogey]

Turn the power off. I cannot emphasize this enough. The worst shock I ever got was performing this test.

With the power off, reach around to the side opposite the motor, and find the motor shaft, as it penetrates the blower wheel. Grab it and attempt to move it side to side, or perpendicular to the shaft. If it moves at all, this indicates a bad bearing and the motor must be replaced. If it doesn't move, it will be worth trying a capacitor, if you don't have any way to test it. If it still wont run, replace the motor.

To replace the motor you will need to remove the blower assy. Hopefully you have plugs for the wires and if you get the exact motor you just plug it back in, if not, cut the wire where you can still see the colors.This is good, because then you can take it out of that hot **sed attic and work on it in the shade. If it's pretty dirty. wash it clean with a spray nozzle, as you cannot hurt it at this point, so you might as well have it clean. At this point, note the position of the blower wheel, the direction of travel will be the direction the blades point. Look at the shaft and sand any rust off of it or you will never get it out. Then loosen the motor setscrew on the shaft, and while holding the shaft with a crescent wrench, attempt to get the wheel to move on it. If it moves, you are good. Then locate the bolts holding the motor bracket to the housing and remove them. If you are very lucky, you will lift up the motor and the shaft will come out of the wheel, and you are ready to locate a replacement motor. Purchase a replacement motor and capacitor, and re-assemble in the reverse order. You will need to be able to read the motor wiring diagram, or if it is an exact replacement it will be easy to rewire.


Or, you can just call a service outfit to replace it. But I would still try the bearing troubleshooting and capacitor first.

And no BS on the power off thing, if there is any power, and the winding is shorted, and the bearing is out, when you rock the shaft you can receive an electric shock. And since you have a grip on the shaft, it will only get tighter, preventing you from getting loose. I discovered this phenomena back in the early 1980's, and as you can tell, the experience has stuck with me. I would not attempt this at all without a working voltmeter and the knowledge to use it. I wont touch anything without using a voltmeter first, and often testing the voltmeter to make sure it works. Good luck with your fan issue.

[be12hunt]

Turn the power off. I cannot emphasize this enough. The worst shock I ever got was performing this test.

With the power off, reach around to the side opposite the motor, and find the motor shaft, as it penetrates the blower wheel. Grab it and attempt to move it side to side, or perpendicular to the shaft. If it moves at all, this indicates a bad bearing and the motor must be replaced. If it doesn't move, it will be worth trying a capacitor, if you don't have any way to test it. If it still wont run, replace the motor.

To replace the motor you will need to remove the blower assy. Hopefully you have plugs for the wires and if you get the exact motor you just plug it back in, if not, cut the wire where you can still see the colors.This is good, because then you can take it out of that hot **sed attic and work on it in the shade. If it's pretty dirty. wash it clean with a spray nozzle, as you cannot hurt it at this point, so you might as well have it clean. At this point, note the position of the blower wheel, the direction of travel will be the direction the blades point. Look at the shaft and sand any rust off of it or you will never get it out. Then loosen the motor setscrew on the shaft, and while holding the shaft with a crescent wrench, attempt to get the wheel to move on it. If it moves, you are good. Then locate the bolts holding the motor bracket to the housing and remove them. If you are very lucky, you will lift up the motor and the shaft will come out of the wheel, and you are ready to locate a replacement motor. Purchase a replacement motor and capacitor, and re-assemble in the reverse order. You will need to be able to read the motor wiring diagram, or if it is an exact replacement it will be easy to rewire.


Or, you can just call a service outfit to replace it. But I would still try the bearing troubleshooting and capacitor first.

And no BS on the power off thing, if there is any power, and the winding is shorted, and the bearing is out, when you rock the shaft you can receive an electric shock. And since you have a grip on the shaft, it will only get tighter, preventing you from getting loose. I discovered this phenomena back in the early 1980's, and as you can tell, the experience has stuck with me. I would not attempt this at all without a working voltmeter and the knowledge to use it. I wont touch anything without using a voltmeter first, and often testing the voltmeter to make sure it works. Good luck with your fan issue.

This is good info.

Low refrigerant could possibly be an issue for the blower motor. If the evaporator coil freezes over it can cause the blower motor to overheat. This could have possibly been your issue if the condenser was running for long without the blower. It is not likely this, but it is possible.

[HuntForHorns]

Turn the power off. I cannot emphasize this enough. The worst shock I ever got was performing this test.

With the power off, reach around to the side opposite the motor, and find the motor shaft, as it penetrates the blower wheel. Grab it and attempt to move it side to side, or perpendicular to the shaft. If it moves at all, this indicates a bad bearing and the motor must be replaced. If it doesn't move, it will be worth trying a capacitor, if you don't have any way to test it. If it still wont run, replace the motor.

To replace the motor you will need to remove the blower assy. Hopefully you have plugs for the wires and if you get the exact motor you just plug it back in, if not, cut the wire where you can still see the colors.This is good, because then you can take it out of that hot **sed attic and work on it in the shade. If it's pretty dirty. wash it clean with a spray nozzle, as you cannot hurt it at this point, so you might as well have it clean. At this point, note the position of the blower wheel, the direction of travel will be the direction the blades point. Look at the shaft and sand any rust off of it or you will never get it out. Then loosen the motor setscrew on the shaft, and while holding the shaft with a crescent wrench, attempt to get the wheel to move on it. If it moves, you are good. Then locate the bolts holding the motor bracket to the housing and remove them. If you are very lucky, you will lift up the motor and the shaft will come out of the wheel, and you are ready to locate a replacement motor. Purchase a replacement motor and capacitor, and re-assemble in the reverse order. You will need to be able to read the motor wiring diagram, or if it is an exact replacement it will be easy to rewire.


Or, you can just call a service outfit to replace it. But I would still try the bearing troubleshooting and capacitor first.

And no BS on the power off thing, if there is any power, and the winding is shorted, and the bearing is out, when you rock the shaft you can receive an electric shock. And since you have a grip on the shaft, it will only get tighter, preventing you from getting loose. I discovered this phenomena back in the early 1980's, and as you can tell, the experience has stuck with me. I would not attempt this at all without a working voltmeter and the knowledge to use it. I wont touch anything without using a voltmeter first, and often testing the voltmeter to make sure it works. Good luck with your fan issue.

Thanks for the great info!

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[-HIC-]

Turn the power off. I cannot emphasize this enough. The worst shock I ever got was performing this test.

With the power off, reach around to the side opposite the motor, and find the motor shaft, as it penetrates the blower wheel. Grab it and attempt to move it side to side, or perpendicular to the shaft. If it moves at all, this indicates a bad bearing and the motor must be replaced. If it doesn't move, it will be worth trying a capacitor, if you don't have any way to test it. If it still wont run, replace the motor.

To replace the motor you will need to remove the blower assy. Hopefully you have plugs for the wires and if you get the exact motor you just plug it back in, if not, cut the wire where you can still see the colors.This is good, because then you can take it out of that hot **sed attic and work on it in the shade. If it's pretty dirty. wash it clean with a spray nozzle, as you cannot hurt it at this point, so you might as well have it clean. At this point, note the position of the blower wheel, the direction of travel will be the direction the blades point. Look at the shaft and sand any rust off of it or you will never get it out. Then loosen the motor setscrew on the shaft, and while holding the shaft with a crescent wrench, attempt to get the wheel to move on it. If it moves, you are good. Then locate the bolts holding the motor bracket to the housing and remove them. If you are very lucky, you will lift up the motor and the shaft will come out of the wheel, and you are ready to locate a replacement motor. Purchase a replacement motor and capacitor, and re-assemble in the reverse order. You will need to be able to read the motor wiring diagram, or if it is an exact replacement it will be easy to rewire.


Or, you can just call a service outfit to replace it. But I would still try the bearing troubleshooting and capacitor first.

And no BS on the power off thing, if there is any power, and the winding is shorted, and the bearing is out, when you rock the shaft you can receive an electric shock. And since you have a grip on the shaft, it will only get tighter, preventing you from getting loose. I discovered this phenomena back in the early 1980's, and as you can tell, the experience has stuck with me. I would not attempt this at all without a working voltmeter and the knowledge to use it. I wont touch anything without using a voltmeter first, and often testing the voltmeter to make sure it works. Good luck with your fan issue.

This is good info all the way around. I know many people that work on things 'hot' to save time. No matter how careful you are, you could be one drop of sweat away from loosing your life. This is a huge issue when working in an attic or outside in the Texas heat.

[double bogey]

The hum, is the motor not starting. It can be either from a bad capacitor, bad bearing, or shorted winding. If you bumped it and it started and stopped after a few mins, I would vote a bearing.


The information in this post and the previous post assumes that you have a capacitor motor. I think after 2017 that manufacturers do not ship capacitor motors in heaters anymore. Its an efficiency thing, as variable ECM and Constant torque motors are 25% more efficient than capacitor motors. I believe these motors have ball bearings instead of the sleeve bearings that most capacitor motors have. If your motor is an ECM and if it is out of warranty, be prepared to spend as much as 4 times what a capacitor motor costs.