My blower motor is possessed

[gottafesty]

So, I've been driving all day with the a/c on switching fan speeds between 1 and 2 occasionally without any issues. As the day wears on and the sun drops lower I turn it all the way off. About sun down I stop at DQ and get a moolatte. MMMM, MMMMM! Now I'm a little cold so I turn the heater on but the fan won't come on. I pulled over and fiddled with all the hvac controls, pulled fuses, nothing. I pull back out and the fan turns on. A couple of days later I turn the fan on and nothing. When I got home I pulled the hvac panel and the fan came on. I checked the connectors and was unable to get the fan to turn off. I wiggled everything under the dash. Nothing changed. So, I put it back together and the fan doesn't work. I slide the top lever, the one that controls the output dampers, and the fan comes on. I side it back and it turns off. I pull the panel again and pull on all the connectors and wires but can't do anything that affects the fan. I put it together and it doesn't work. I reach under the dash and and tap on the fan box. The fan comes on so I drive off to take care of some stuff in town. As I accelerate up the hill the fan speed slows down. As I let off to go down the hill fan speeds back up. I then press the accelerator and the speed goes down again. I let up and the fan speeds back up. I romp on it and the fan dies completely. I let up and the fan comes back on. When I get to town I shut off the car and take care of my business. When I start the car back up the fan comes on nice and loud and I haven't had a problem since then which was Saturday afternoon. What gives????

[sasquatch]

i think a copple of the cars had a random setting... very rare

[gottafesty]

very rare!?

hmmm, to the "for sale" forum I go. :lol:

[scitzz]

Mine did something similar for a long time. One day, I got tired and pulled the fan out. Inside were, as I remember, 2 contacts held in place with a small spring. One of the springs was slightly sprung, and contact was not always what it could be. Canabalized a "clicky top" pen for a spring, and have never looked back.....

[bassman]

mine did that at 130 000 k just befor it quit all toghether.
best be lookin for a new one and change it out when you have time.

[jglutz]

is the linkage between the gas pedal and the fan control on backwards? The fan should speed up when the engine speeds up.

Serioulsly....very odd. my recommendations:
1st)Hang a voltmeter on the power suppling the fan controls to see if it a volatge supply problem.
2nd)Are the fan motor brushes extremely worn and the commutator cloged with the residual carbon? This problem, brushes/commutator, commonly effects the high spped performance of a DC motor...however this does not explain the relationship to the engine RPM.