70 ctls

Repairing the AC unit. When switched ON the compressor kicks in. When switched OFF the compressor stays engaged. To get it to go off I need to turn the car off and restart. Is it a relay and where is it on a '70 Cutlass Supreme?

tru-blue 442

That's how they work in this year.

MDchanic

It's called the "hold-in relay."



It's not a bug - it's a feature.

- Eric

Fun71

Yep, that's how the system was designed in the 70-earlier cars.

Back in high school I installed a toggle switch in my 70 Supreme so I could shut the compressor off without turning in the ignition off.

VC455

The A/C relay is bolted to the top lip of the passenger fender, in the engine compartment, about halfway from the dash to the headlights.

oldspackrat

basically mirrors the horn relay.

70 ctls

Thanks for the feedback but quite frankly I'm confused. My '69 with stock AC unit turns the compressor clutch on and off with the in dash switch, yet i'm hearing that my '70 was built to stay on until the car is turned off. Hmmmm.

Zr1bandit

Confused also-----what is correct here ???

tru-blue 442

My 69 442 also worked like the 70. You had to turn the ignition off for
the clutch to disengage. Sliding over to off wouldn't do it.

MDchanic

Your Owner's Manual or Chassis Service Manual will describe the operation of your heating and cooling system.

- Eric

VC455

You are probably wondering why GM started using a hold-in relay.

They had liability and safety concerns that someone would turn off the AC and the moisture remaining on the evaporator would end up as fog on the inside of the windows. Someone would have an accident.

The solution was to not let the compressor shut off until the car was stopped.

70 ctls

Thanks VC, I get it now! Safety First.

mpolds

And I have exactly one (1) remaining --N.O.S. ---- and it looks like 3 different people are looking for one right now !!!!!!!!!
This is the third different thread I am responding to ---and the one from yesterday NEVER called.........
I have exactly one (1) A.C> Compressor Hold In relay , as it is called, and I will be in New Jersey at R I 27 @ Englishtown
for the next four days -- Thursday, September 27th -through - Sunday, September 30th.....

You are welcome to call me tonight ---- Craig..... West Hempstead, New York, ....... 516 - 485 - 1935.........

tru-blue 442

Craig, post a pic with a price in the parts for sale section, it will sell.