air con won't blow
I'm working on a roof unit in which the squirrel cage blower motor won't run. With power off, it spins freely by hand. With power on, the motor hums but does not run, and if I try spinning by hand the...
Forum Discussion
This is a simplified version from RVP. Doug
Set the system controller to call for cooling
operation. Temporarily restore power to the air
conditioner taking care to avoid moving parts. If
the motor will not start, while energized quickly
spin the motor by hand in the usual direction of
rotation. If the motor comes up to speed and
continues to run, remove power and check the run
capacitor. If a capacitor checker is unavailable,
substitute a known good capacitor of the same
rating. If the motor now comes up to speed
without assistance, the original capacitor was
defective. If the motor will still not start without
assistance, the motor start winding is open or
badly shunted and the motor must be replaced
Set the system controller to call for cooling
operation. Temporarily restore power to the air
conditioner taking care to avoid moving parts. If
the motor will not start, while energized quickly
spin the motor by hand in the usual direction of
rotation. If the motor comes up to speed and
continues to run, remove power and check the run
capacitor. If a capacitor checker is unavailable,
substitute a known good capacitor of the same
rating. If the motor now comes up to speed
without assistance, the original capacitor was
defective. If the motor will still not start without
assistance, the motor start winding is open or
badly shunted and the motor must be replaced
