Replacing heater fan motor - Tips on how to do it ?

All,

I think my wife's old 91 accord has finally finished off
the heater fan. The car has about 245k miles, so I guess
its time. I would like bounce a few things off the group
and then get suggestions on how to proceed to get the
old unit out and the new motor back in.

First, the fan doesnt run in any of the fan control positions,
and the AC compressor will not engage when the AC switch
is depressed. I assume the AC control system knows if the
fan is running and won't engage the compressor if it detects
the fan is not running ? I have checked the fuses but not
any of the relays, do I need to ? Also the motor apparently
just stopped working while my wife was driving the car, there
were no earlier symptoms of a pending failure.

Assuming the above is true, then the motor, being DC, probably
has worn out brushes. And I assume it is not worth it to
try to repair the motor.

OK so how do I get at the darn thing, after poking around under
the dash on the passenger side it looks like a big complex
mess. Where do I start ? I have never removed any part of the
dash before so I assume I start in that direction.

Any help would be very much appreciated.

Regards, Steve

 

If the AC won't come on either, I would check the switch first before going
into the motor.

 

Yeah, I'd second that. Ground is brought to the blower switch in a black
wire. The five wires which are various flavors of blue go to terminals of
the resistor. The green wire is the input for the A/C control.

Short Blue/Red to a good ground (don't use the black wire) and the blower
should spring to life. Disconnect it, and check the other four blue
variation wires by shorting to ground to see if your resistor pack is
working. Now move your temporary ground connection to the black wire. If
the switch is good, you'll get the same results indicating a bad ground. If
things stop working, your switch is bad.

While you're in there, you can also temporarily short the green one to
ground to ensure that A/C will run. Don't do it long since you'll just form
ice on the condensor if you run it without the fan blower running.

-Arthur