isnt it funny how when summer hits, there is a surge in A/C related questions?


anywho, i'll make this quick. On a 94 E420 the blower motor doesnt turn on. All fuses check so I have no other option but to assume something it up with the motor. so....when I take the motor out...what do I check? what do I replace? how do I rebuild it, and where do I get the stuff to do it?


EDIT: oh and whats a "blower motor resistor?" where is it and how do I check its functionality?

First thing to do is connection the blower motor directly to a 12v source (AKA the battery of your car) and see what happens. Either it will spin, or it won't spin.

If the blower doesn't work, take a look at the brushes. See how worn they appear to be, try jiggling them around in the channel in which they run (they are spring loaded to maintain contact as they wear). You can buy new brushes from George Murphy (search the archives for his contact info). Or replace the blower motor.

If the blower works, then it's time to troubleshoot the blower regulator. This car does not have a resistor pack, it uses an electronic regulator to control blower speed. The regulator itself is located near the blower - I think it's directly underneath. The airflow from the blower cools the regulator.

Use the search feature to find instructions on testing the regulator. You need a simple volt meter to determine it has power, ground, and the signal from the push button unit. Based on a quick assessment, you can isolate the problem to the regulator or the PBU.

- JimY