If the car ac blower motor does not work at all, the blower motor itself must be tested first. Usually, it is done by measuring the voltage on the blower motor connector when it is turned on. If there is the voltage on the motor (low speed at least 4-6 volts, high speed at least 12 volts), but the motor does not run, the motor is damaged or stuck.
Leaves, branches, nuts, and broken cabin filter debris can clog the blower motor blades. This happens frequently in many cars.
If there is no voltage on the motor, the entire blower motor circuit must be tested starting from the fuse.
If the blower motor is damaged, it needs to be replaced. The replacement cost of the blower motor depends on the car. In many cars, this is fairly easy. The blower motor is located behind the glove box and is fixed by 3-4 screws. In other cases, it may be located on the dashboard (e.g. Mazda 5), so it is difficult to replace.
Another method is to check the voltage of the blower motor, blower motor control module, and other parts of the circuit according to the maintenance manual. For example, in Honda Blower Motor AY272700-5400 LHD, the +12V power supply is directly supplied to the blower motor through a fuse and then a relay. The blower motor control module (which Honda calls a power transistor) powers the ground. The power transistor has 4 wires: two from the climate control system control unit, one is the ground wire, and the other is connected to the negative pole of the blower motor. The maintenance manual recommends measuring the voltage on the blower motor, if it is abnormal, then measuring the voltage on the power transistor, and so on.
Post time: Jun-29-2020