Kevin in Atlanta

A local 1985 928S owner stopped by yesterday with an interesting AC issue. The AC blows cold. But...

Intermittently, the AC and the blower stop working. When this happens you can hear the AC auxiliary fan quit at the exact moment the blower motor stops and the AC button light turns off.

Blower does not come to life with the selector pushed to defrost. I think that rules out the resistor pack.

I don't think the HVAC head relay failure ever shuts off the blower motor.

My sense of logic thinks there is somewhere the 12 volts going to the HVAC is dropping out. But, does that explain the AC button light going out?

Any suggstions are appreciated.

Here's a picture of the car. Mocha Brown, no rub strips. Beautiful car inside and out.

Billu

First thing i’d Check is the contacts/wipers in the climate control selector.
My 80 has developed an issue where in some positions I get no fan or a/c, sometimes just no a/c, and sometimes everything works.
Moving the selector to about 1/2” either side of the auto position usually makes everything work, but I sometimes have to move the **** just a hair to get things to re-engage. Just started about two weeks ago, and I just received new ***** and springs from Roger, so I waited to tear things apart.
Project for this coming week.
Without looking at a model specific wiring diagram, I don’t know if the a/c light is fed through the controller, as my car doesn’t have the light.

dr bob

Replace the blower relay. It powers the whole system.

Kevin in Atlanta

Will do!