Mauireman

Thanks I’ve had the controller out b4 yrs ago to do the A/C clutch rely replacement. That’s still working fine.

My fresh air blower works when the lower control lever is moved to defrost, even when the speed control switch is unplugged from the controller! And when the speed control switch is plugged into the controller the blower works on high only when the lower control lever is in any position except off. None of the male pins coming out of the control unit that the blower speed switch plugs into has power? Shouldn’t the #1 pin have 12v ?

Anyone have any ideas? Other than something in the control unit not sending power to the speed switch, if it’s supposed to, the only other component is the Resistance Group? FYI my car had the Additional AC unit in the back seat and the blower works fine on it.

HELP I’m stumped!

Thanks
Dan

buccicone

Look at the resistor pack under the cowl inside the evaporator box.

mskar

Just went through this myself, there are several useful articles on this keep in mind there are “early” and “late” resistor packs. You can pull the resistor pack w/o too much trouble by removing the rubber boot and holding onto the resistor pack w a magnetic grabber, disconnecting the harness, and unscrewing the mounting bolts. Pull the cage off it and test your coil resistances to the values stamped on coil towers. In my case (high blower only), the contacts on the tiny switch that runs down the center weren’t making contact. I doubled over a small strip of fine grit sandpaper, slipped it between the contacts and cleaned it up. Spritz of deoxit, cage-on, fished it back in and held it in place from the mounting whole (gently) with needle nose vice grips until i could get a screw started and bob’s your uncle.

lots of great articles on this

Wisconsin Joe

To make sure I understand:

Your blower fan works, but only blows on high, no matter what you set it at?

I'll agree that the next place to look is the resistor pack.

Search "Magic Blower" to find a lot more info.

There's a removal trick where you put a wood screw (or sheetmetal screw) into one of the open holes in the housing, tie a piece of string to the screw, then pull it out of the tube. Untie the string and leave it in the tube. When you put it back, use the string to pull it back into place, then use the screw as a handle to hold it precisely in position so you can secure it.

Mrmerlin

Before you replace any parts please get a new 53 relay and install it in the X position
also install a new blower relay do one at a time then check operation
The 85 I am working on had the same issue no blower unless it’s on defrost a bad X relay was the culprit

Mauireman

I got the resistor pack out and there was no continuity across the micro points in the middle, cleaned them with some 1500grit sand paper and now have continuity across them. Tomorrow I’m going to get some DeOxit and clean the points again then put everything back together abs see what happens?

Thanks
Dan

Mauireman

It Works!
The problem ended up being the Micro points in the resistor pack! I cleaned them with 1500 grit paper and I now all the fan speeds Work! I’m waiting for some Deoxit to be delivered b4 I put everything back together then off to an AC shop!

THANKS TO EVERYONE for the help!
Dan