Connect vacuum tester to the vacuum motor and apply-510 mmHg pressure.
Check vacuum hiss from the vacuum motor and that the shaft return smoothly to initial position. If not OK, replace the vacuum motor.
NOTE
Never manually operate any vacuum motor or vacuum motor controlled door. This may cause internal damage to the motor diaphragm.
BLOWER MOTOR
Check for bending or abnormal deflection of the rotating shaft of the blower motor assembly.
Check for cracking or deterioration of the packing.
Check for damage to the fan.
Check for damage to the blower case.
Check the operation of the inside/outside air selection damper, and for damage.
Connect the blower motor terminals directly to the battery and check that the blower motor operates smoothly.
Next, reverse the polarity and check that the blower motor operates smoothly in the reverse direction.
BLOWER RESISTOR
Measure terminal-to-terminal resistance of the blower resistor. If measured resistance is not within specification, the blower resistor must be replaced.
NOTE
Never weld the blown-out fuse in the blower resistor. Just replace the blower resistor.