A/C blower dial operates headlight washer

[dyerkes]

I have an issue with my recently purchased 1987 911 Targa. When I turn the A/C fan dial instead of the fan turning on the headlight washer pump begins spraying the headlights. Any tips as to how I go about diagnosing the source of the problem would be greatly appreciated.

Regards,
David

[DRACO A5OG]

Check your fuse panel, wires may be crossed.

[ganun]

Agree, with the fan dial knob ON check the the A/C clutch is engaged, front condenser blower is on( in the trunk by the spare tire) and the cabin a/c blower is on. If any of the above is not ON that would be the wire to check if it's crossed. BTW, A/C gets power from fuse #2 (blue 25 amp fuse).
I just happen to have this handy for 87 a/c.

[jbm911]

Definitely check your fuse panel, as noted above the ac system is fuse 2, and right next to it in the number 3 position is the headlight washer (at least it's like that on my 89).

[dyerkes]

Thanks for all of the responses. The front condenser motor is definitely not turning on when the A/C fan dial is turned. I have verified that the motor is in good operation by jumping it directly with 12v, so I guess I will start with the wires that run to the motor as well as those that run to the headlight washers.

Thanks,
David

[BrianS]

Wow. I can't believe it. My car is doing the same. Haven't dove in yet but I can tell you the last owner was a complete idiot.


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[Jonny H]

It could be a grounding issue, as both washer and fan are in the nose of the car. Check the chassis earth stud near the battery and all associated wiring.

[uwanna]

Originally Posted by Jonny H

It could be a grounding issue, as both washer and fan are in the nose of the car. Check the chassis earth stud near the battery and all associated wiring.

^^^ What he said! Had a weird "ground loop" problem myself. Sometimes, when I activated the left turn signal, the wipers would take a "swipe". Chased thru the wiring with a multimeter, disconnected wires etc. The problem was a grounding problem at the
chassis grounding stud from the battery negative strap. There is a "stack" of wire connectors there. I took the stack apart and cleaned the corrosion off the individual connectors, and VOILA, problem fixed!!

[dyerkes]

I really appreciate all of the great input. I will take a break at lunch to check and clean the ground connections as indicated. If that doesn't correct it I will proceed to test each connection until I uncover the root cause. Thanks, and I will report back on my findings.

Regards,
David

[dyerkes]

I just cleaned the ground point and all of the wire connectors and re-tested only to get a similar results (when I turn the a/c fan switch to the on position the headlight washers begin spraying non stop until I shut off the fan. The contact points were dirty on most of the connections, so I initially was hopeful that it would have been the root of my problem. Certainly didn't hurt to clean them, but I have to continue to with my search of the cause.

Regards

[dyerkes]

Problem solved! Someone had plugged the wrong connectors to the wrong devices (headlight washer was hooked into the a/c condenser fan wiring and vice versa). Both devices use the same type of connector, and are both located immediately in front if the battery, so it's easy to see how someone could have mistakenly swapped them. The key is the color of the wiring (white/green for a/c condenser fan, and yellow/black for headlight washer - '87 911). Thanks for everyone's assistance!

David

[ganun]

Hahaha, so trivial, yeah Porsche didn't mistake proof much back then, it's 70s engineering
Glad you figured it out.