YOU WILL HAVE TO INCREASE THE IDLE RPM.
no just the motor shuts down
well that means that your car just BLOWS
Replace blower motor it's burned up.
motor shuts off when put in gear sometimes
It sends a signal though one of you motors kill/stop switches and shuts the motor off.
Not sure why you are describing the shut down as being power factor related. If it shuts down after a short period I would expect that the motor has a thermal protection cutoff and the shut down is being caused by a bearing over heating.
It may be heating up too much. There is a sensor that shuts down the motor when it gets too hot to keep from damaging the motor.
Two possible issues The motor may be bad and the control shuts down when it is turned up to protect the control The control is bad
The compressor may have locked up, do you hear a squeal before the engine shuts down?
t.p.s throttle position sensor
If it shuts off then comes back on later it's almost certainly the switch... but. Never replace anything until you've checked it. Put a test light/meter on the heater motor then run it until the motor shuts off, then look at the meter. If the voltage is zero, or practically zero, it's the switch. If the voltage is up near normal (12.5 - 14) it's probably the motor.
we would need to know what kinda car it is and what motor to give u an idea