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Weak Fan Motor

I had the fan motor replaced on my 99 Mercury Villager. Since I got it fixed, the volume of air that is pushed through the vents is very weak. I’m afraid that when cold weather really gets here, there won’t be enough air to keep the windows clear of ice and fogging. The repairman said that I probably have a leak in the “Air Box”. Prior to the fan going out, there was never a problem with airflow in any way. He said that he had a hard time finding the right size fan and an electrical part that I can’t remember now what. Any ideas on what I might look for besides the “Air Box” ?

Some aftermarket blower fan motors require cutting off the plug from the original motor and connecting it to the new motor. If the wires are reversed when doing this, the blower motor will run backwards which causes the fan to rotate backwards which will produce little or no air flow.


Is it hard to trace the wiring to the motor to check this? Where is the motor located on this car?

Another part? Perhaps an adapter cable?

There are a few possibilitiies I can think of. A poor connection (if he hard-wired it) or a burned relay contact. If it were me, the first thing I’d check it to see if I had the full 12VDC at the fan with the fan switch on high. If not, then I’d go looking for the resistance in the circuit by tracing backwards with a pin probe.

The motor is a DC motor. The lower the voltage, the slower the motor runs. If theres a resistance in the circuit it’ll “drop” the voltage to some reduced level and the fan will run slower.

The blower motor is located under the dash passenger side. You may have to remove a panel from under the dash to gain access to the blower motor/connector.