HVAC part identification. HELP.
Thanks in advance,
Rusty




I tag along in the topic.
I am helping my father in his 1987 300DT and the blower is intermittent.
I searched the section and tons of blower topics, but most of them flooded by forum spammer and none of them come with good conclusion.
Father's blower comes on restarting the car, or sometimes few minutes into the drive on its own. Drives me crazy.
I replaced all the controls, file up ignition switch contact, check the plug behind brake booster and although now the blower comes all the time on my driveway, on last longer drive it died. I took it home and tested the fuse to have power.
Look like the mechanic above knew something about the issue and add additional switch.
I am tempted to do the same, but with heating module, where to tap the power?




After dropping several parts and still having intermittent hang-ups I finally went for easy part.
Blower motor. It is easy part, but not so easy access, but having 5 cars on junk yard, I broke some parts on 1st and took me about 10 minutes to get to blower motor on 2nd one.
Old blower on father's car still has long brushes, but "somebody was there before"
Whole wiper assembly was hanging on 1 nut + the shape fit. Old blower motor had additional wires solder to it. My conclusion is that the wiring on commutator has to have dead loop or 2 and when it works on high most of the time, once you turn it to slow it will stop and not restart till some shaking.
Regardless the age, it is pretty complex system. The cabin controller sends signal to blower controller under the motor.
When you measure it on 3-pin plug behind master cylinder, slow speed is 1V, high speed is 9V and anything between on auto mode.
If you measure steady 12v on center pin and above voltage on right pin (looking from front of the car) that means your problem is on the motor, or its direct controller.
Now neutral safety switch was not that bad job, but extremely dirty.
Last edited by kajtek1; Aug 8, 2016 at 09:57 PM.


