Only have the middle speed on the fan. Tested to motor and it runs full speed when powered directly at the motor. Pulled the control and cleaned the contacts.
I am wondering if the problem is in the terminal block at the fan. I am thinking there was a resistor in there.
Any ideas?

I have never had one apart, but I'll bet the technology is near ancient. Trying to recall a similar issue with only one speed working on an old Dodge and a failed resistor just might have been the cause. Probably 40 or 50 years ago

There are a pair of resistors in the housing of the fan. IIRC, high speed grounds by bypassing both resistors, mid speed grounds through one, and low through both. Not 100% sure that's how it works, but something like that.

My low speed resistor burned up at one point from too much resistance so I only have medium and high as well. I remember seeing the little puff of smoke come up through the vent...

I've wondered whether a more efficient blower could replace the original. The fresh airfaninmy '91 Volvo really puts out ?

does it blow a fuse if you leave it on low or high? mine did this and it turned out the previous owner had but the fuse block back in but crossed the wires so medium worked but high and low blew the fuse because it was shorting out.

regarding the resistor thats possible the resistor is gone or its just that the controller has warped and its not touching on low . to test this you can pull the wires and connect a different controller to see if thats the issue.

@jim_hoyland
Jim, new fans with new motors are available and they really crank on high. the old fan bearings could be the issue and not letting it spin freely.

@bdstone914
If the resisitors are bad( you can test them) i think i have a second set of good ones in my box, let me know.

Phil

this might help- some info about the resistors etc in this tread

http://www.914world.com/bbs2/index.php?sho...=351152&hl=

Did you snort that puff of smoke