Bones944

My 87 951 developed a quirk today, the fan switch only works on the 4 (high) position. Switch problem or blower motor? Seems obvious it would be the switch, but seems to me several years ago I had another car that developed the same problem and it ended up being something else.

Type_LT

Funny you should mention that, I had the same exact thing happen a couple days ago. I was sitting in the car with the a/c on and the dial at the 2nd position, then all the sudden the blower shuts off, the car isn't even moving the only vibration is the engine. I turn it to the 3rd position, nothing, turn it to the 4th and woosh it comes to life. About 10s later the fan works in all positions. I'll be thinking about it, my first thought was the resistors in the passenger side dash...

Bones944

Well i hate to tell you but mine did the same thing about twice in the past week, briefly quit and then came back....this time it didn't come back! Where are the resistors?

Jim 944S

I've always thought it was dirty contacts in the switch causing the problem. Seems to behave in an erratic manner... sometimes works in all positions, sometimes on only some. One of us will have to pull it apart and look... Gotta do my fuel lines first!!!

Jim <img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

RJB

Did anyone figure out how to fix this problem? My '87 was working fine, but all of a sudden, the fan will only work on high (position 4). I plan to pull apart the control tonight or tomorrow, but I was wondering if anyone else found out how to fix it. If I find the problem, I will post my solution.

Thanks

Dave in Chicago

Resistor pack in the airstream of the blower motor under the hood? If not specifically AC-related, these get dirty/shot and will fail to work fan in positions 1,2, and sometimes 3. Try swapping it out with a buddy if you can to test it. It's an expensive (but easy to change) little part at $100+.

Keep the shiny side up,

jim968

Almost certanly the resistor pack... the speed of a DC motor is controlled by changing the voltage. Applying the full 12+ volts equals full speed; voltage is dropped across resistors for slower fan speeds (more resistance = slower speed). Lowest speed uses all the resistors, intermediate speeds bypass some resistance.

Resistor pack failure typically results in getting voltage to the motor only in the high setting.

Jim, "ELC 101: Introduction to DC"

RJB

Finally got to work on the car last night - and just as the previous posts indicated - it was the resistor pack. I pulled it out, cleaned it with contact cleaner, measured the resistances to be sure it was working, put it back in and the fan works perfectly now. This was one of the easiest fixes yet!

Thanks for all of your help!