HOT fan switch

[Mark Kevin Weaver]

My 76 NYB has a VERY hot fan switch when set at any speed higher than low.
Any idea what the issue is and how to fix it?

 

[Davea Lux]

My 76 NYB has a VERY hot fan switch when set at any speed higher than low.
Any idea what the issue is and how to fix it?

You should start by running a load meter test on the blower fan motor. It should be drawing about 16amps of less at the high speed. If that test normal, the contacts in the switch are probably corroded. If you are careful you can take the switch apart and sand the corrosion off of the contacts and re-assemble the switch. Before taking the switch apart, you can use an ohm meter to test the resistance in the switch at each speed setting to verify that it has high resistance. Shorted blower fan motor windings or partially seized shaft bearings will cause the motor to draw excessive amperage. If that is the case it is usually best to replace the motor.

Dave

 

[Mark Kevin Weaver]

You should start by running a load meter test on the blower fan motor. It should be drawing about 16amps of less at the high speed. If that test normal, the contacts in the switch are probably corroded. If you are careful you can take the switch apart and sand the corrosion off of the contacts and re-assemble the switch. Before taking the switch apart, you can use an ohm meter to test the resistance in the switch at each speed setting to verify that it has high resistance. Shorted blower fan motor windings or partially seized shaft bearings will cause the motor to draw excessive amperage. If that is the case it is usually best to replace the motor.

Dave

Thank you, Dave. I replaced the switch and cleaned the connections thinking that was the problem. I'll check the resistance at the motor now.

 

[Sixpactogo]

I'm betting your blower motor is dried out. Running on high will melt the switch contacts in short order.