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1980 AC only operates when in reverse, nothing in Drive

1986glht

New member
Joined
Jun 3, 2017
Messages
3
Location
Delaware
At my wits end!

Been trying to track down a/c or fan not working.

Today feeling frustrated put the car in reverse hit the gas and miracle of miracle freezing cold air and the fan blows at all speeds. But it back in drive and nothing works. I was able to repeat it at will.

Any thoughts? Anyone had this problem and found the fix?

Thanks,
Guy
 
Last edited:
Thats a new one..have you done any wiring in or around the dash
Or fan switch????

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I have ohmed blower resistors, continuity checked leads to blower relay, jumped blower relay to verify operation.

I have also continuity checked blower fan switch. All the above have tested OK.

The blower motor didn't seem to spin freely although it ohmed correctly I replaced it while it was out.

I don't have a service manual, and I was wondering if the is a single source (wire) that supplies the entire the a/c and blower system. When the engine rocks it might be in a position the pinches the power supply.
 
That's strange. I'd start by tracing the wiring looking for damage, checking the grounds to be sure they are tight and checking all the plugs to be sure they are tight and not corroded.

Tom
 
I don't have a service manual, and I was wondering if the is a single source (wire) that supplies the entire the a/c and blower system.

No. There's a separate supply for the blower and the compressor clutch. Find out if it's one or both that are not getting power. Maybe a previous owner wired them through the back up lights?
 
Tom and Mikey thanks for the replies! With what I found today I'm confident with a little more detective work it'll be fixed. When it's fixed I'll share what the problem was.

Guy
 
My guess is that the problem is under the hood
When in reverse 2 thing's happen,
1 is the reverse light circuit is powered up and we all know that has nothing to do with it, unless Mikey is correct
2 the engine torque is backwards meaning the passenger side is lifting which in turn is pulling/pushing on the wiring making a momentary connection somewhere or completing a ground path

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2 the engine torque is backwards meaning the passenger side is lifting which in turn is pulling/pushing on the wiring making a momentary connection somewhere or completing a ground path

Sent from my SM-N920P using Tapatalk

Doug, your 2 might be it.

I had a similar issue with one of my PUs. Put it in reverse and the check engine light would come on. It turned out to be the wire to the sensor in the exhaust pipe was too long and the insulation was burnt off. Put it in reverse and it was 50-50 the wire would touch.
The tech said when he backed it up, the light came on and the scan tool said it was the same thing he just replaced. He said he called B$ and finally looked..

They replaced almost every module under the hood and fortunately for my wallet, it was all warranty.


 

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