I recently replaced my entire air conditioning system. The furnace was fine so I kept it from the trash heap. I removed the fan assembly from the housing. My extension is to build a "blower box" to blow ambient air. Not sure what we're going to do with it, but it was fun for the kids to learn about motors an fans. But when I was finished and plugged the fan in, the motor started to overheat, you could smell it. I reduced the speed of the fan by changing the wiring to the motor but the overheating persisted. Any thoughts as what is causing this? I have no way to measure AMP consumption.

Thanks,

Mark

Caged fan style blowers need a bit of back pressure to prevent them from over running there actual design speed. It could also just be a case of it was time for the motor die. Since you do not need it for anything important other than a experiment it will not have to be replaced so you will not have any additional cost.

I recently replaced my entire air conditioning system. The furnace was fine so I kept it from the trash heap. I removed the fan assembly from the housing. My extension is to build a "blower box" to blow ambient air. Not sure what we're going to do with it, but it was fun for the kids to learn about motors an fans. But when I was finished and plugged the fan in, the motor started to overheat, you could smell it. I reduced the speed of the fan by changing the wiring to the motor but the overheating persisted. Any thoughts as what is causing this? I have no way to measure AMP consumption.

Thanks,

Mark

Are you sure the run capacitor in it is good?

Are you sure the run capacitor is good?

A cheap clamp on ammeter would be a nice learning tool for you and the kids... or I'm sure you know someone who owns one who could lend it to you. Make it a learning experience for you and the kids.

Caged fan style blowers need a bit of back pressure to prevent them from over running there actual design speed. It could also just be a case of it was time for the motor die. Since you do not need it for anything important other than a experiment it will not have to be replaced so you will not have any additional cost.

Back pressure was my first thought but when I slowed the motor down and it still overheated I began to question my theory. I'm certain the motor was fine when it was removed. Do you think it will over heat at any speed setting, lacking back pressure. By speed setting I mean simply changing which color wire I'm hoking up on the motor.

A cheap clamp on ammeter would be a nice learning tool for you and the kids....or I'm sure you know someone who owns one who could lend it to you. Make it a learning experience for you and the kids.

Good point, plus it will certainly show if excess current is being drawn by the motor. How would I reduce the current draw? Back pressure?

Are you sure the run capacitor is good?

Capacitor is fine. I think it's lack of back pressure now that it's running outside the ducting system. Just seems more back pressure causes the motor to work harde,r or not?

Without a amp reading I'm suspecting the motor has failed(or failing) bearings or possibly the run wiring has gone bad. Time to say goodbye to it. Most 115v motors should run fine outside a air handler unless there is more to it. Good luck

Without a amp reading I'm suspecting the motor has failed(or failing) bearings or possibly the run wiring has gone bad. Time to say goodbye to it. Most 115v motors should run fine outside a air handler unless there is more to it. Good luck

Thanks you for your time.