1992 300E Blower Regulator Problem?

[sharkdvr9996]

I received a new blower motor today and followed some threads to get the install done. After hooking the motor up and turning on the ignition it did not run. I hooked the new motor to the battery and it started right up.
I tested the voltage at the leads and it is fine.
I hooked the motor back to the car, touched the squirrel cage and it started running. Problem is, it runs at the same semi slow speed no matter which buttons are pressed on the climate control. You can barely feel it on the inside of the car.
The off button does turn it off, and when you switch to A/C the cover lifts in the blower compartment. I am led to believe that the climate contol unit is fine and it is the blower regulator that is not working?

Please help

[stevebfl]

There is a three wire connector on the firewall that has all three vital signals: power, ground, and the control voltage from the pushbutton controller. Unfortunately the blower controller sits in the circuit between the neg side of the motor and ground. The control signal should get close to 6v at high blow.

If the control signal is getting to 6v and the blower speed is low then the next electrical step is to measure the voltage across the regulator. It should get as low as 1v or close to it. By across the regulator I mean from the negative side of the motor to ground should be about 1v in high blow. To measure this you will have to pull it back apart somewhat.

To make things more fun, we have been made aware recently that one can hook the motor up backwards. When this happens the blower spins just fine but the air coming out is very small. One might think it would get sucked in but it doesn't. It still pushes a little but not much. So if it works properly electrically switch the wires

[sharkdvr9996]

Thanks for that information! Since I never saw the blower operate, it is spinning towards the back of the car. I hope thats the right direction. I guess I will have to tackle your suggestions in the sunlight tomorrow. I just tried un-hooking the blue ground from the blower and grounded it on the chasis to eliminate the regulator . I also tried directly to the battery and nothing happened in either case.