my saga trying to fix my blower still continues.....

I've tested all the fuses - all ok

I've removed the Blower motor unit and run it on the bench from a 12v source - worked fine

Connected the blue/black connector on motor to earth - motor didn't run

Tested voltage from blower connector to ground and there is voltage

So now i'm at a bit of a loss as what to do next. There's voltage at the connector yet the motor doesn't run, which it does do on the bench...

any ideas?

thanks,

john.

 

Do you have voltage between the 2 pins on the car connector with the motor plugged in? Measure between the 2 pins, that is more conclusive that the motor will receive power than measuring both to ground.

When a motor is going bad it will often become intermittent first, because the brushes are worn down to where they barelymake contact.

 

You might want to check the ground wires for the blower motor relay and the blower motor itself, as well as the power transistor.

 

my blower motor went because the ground near my passenger side firewall was corroded. Check that, and the relays under the hood.

 

cheers i'll try all the suggestions...

but i'm confused why i see voltage at the plug even when the fan is swtiched off....

john.

 

I think the power transistor switches the ground. If everything is working properly you'll have +12 from either/ both terminal to ground with the fan off and the key on. Maybe even with the key off.

 

Yes, power to the blower motor is controlled by the ignition switch not by the dash fan switch.

When you grounded the BLU/BLK wire from the blower motor was the ignition key ON? How exactly did you do this test? My questions focus on the latter test because you currently have two contradictory test results, one saying the motor is good and the other saying the motor is bad. This discrepancy must be reconciled in order for your troubleshooting effort to move forward.

If the motor is bad, the solution is obvious. If the motor is good, then the problem could be a faulty power transistor, heater control panel, switch assembly, or ground wires.

 

do i have to remove the ECM to get to the power transistor? Looking through the service manual if the job needs to remove the ECM it says so but i can't see how you get to the power transistor without removing the ECM - anyone?

thanks,

john.

 

nevermind, got to the transistor - jumped pins 1 and 3 and motor goes - can't figure out how to remove the 4th connector from the block to try the next test..

and besides, since the fan does occasionally go i'm going to turn my attention to the heater control dials.

 

Really sounds like a bad power transistor. Try wiggling or hitting the transistor to see if it has something loose.

Did you run the control panel self-test? Do the other functions that the panel does (air control doors and rear defroster) work? If the panel seems OK you have a good chance to fix it just replacing the transistor.