dredluxx

Hey guys. Forgive me if this is an amateur question - I'm not used to older cars. When the A/C is "ON', I've noticed that the pulley in the serpentine belt constantly cycles off and on, every 5 or 6 seconds. This seems like abnormal behavior, however the AC is functioning fine and the belts are turning as they should. When A/C is "OFF", it stays stationary. Any thoughts? Input? Thanks.

MDchanic

I am not sure which year the constantly-engaged A6 compressor with POA valve was phased out and the intermittently engaged R4 with pressure cycling switch was phased in, but this would be normal operation for the R4.

- Eric

joe_padavano

First, what vehicle are we talking about? Your Olds doesn't have a "serpentine" belt. It has separate V-belts.

If you are talking about your Olds, compressor short-cycling is an indication of low freon.

MDchanic

You picked up on what I missed, Joe- the 5-6 second cycle time.

In pressure-cycling systems that certainly is a sign of low refrigerant.

- Eric

rocketraider

1982 had R4 cycling clutch compressor and it will engage and disengage based on system pressure. As noted, if the refrigerant charge is low it will either cycle rapidly (low) or stay engaged all the time (extremely low). I've noticed cycling clutch systems will sometimes do that on extremely hot and humid days too even with a normal charge.

Is the system cooling normally, as in 38-42 degree dash outlet air temperature? You need to hook up a set of A/C gauges to see what pressures are doing while all this cycling is going on.

The first cycling clutch system I know of in GM was on 1977 Rivieras using an A6 compressor. Can't help but think those clutches wore out quick cycling that big lunky thing.

dredluxx

Forgive my ignorance. Hopefully I get a pass, still not used to a car this old and I'm not the most mechanically inclined individual in the world. Thanks for the correction, the more you know the better. I always called the belt that kept all the components in the engine bay running a serpentine belt. I guess thats what most newer cars have.

The climate in my area is literally unpredictable other than that the weather changes constantly and rapidly in the "spring" and "fall" seasons, and that it's generally humid. Some days it'll be 75 and the next day it'll be 40. That being said, i usually ride the Delta on warmer days, and with the windows down, so i hardly ever run the A/C anyways. However the other day it was pretty hot and decided to run the A/C for the first time since I got the car.

I dont have any gauges.. Is there any specific set of A/C gauges you guys recommend? Or does a store like Pep Boys or Autozone rent said gauges?


Thanks Eric, Joe, and rocketraider.

MDchanic

The first question is, Is your system charged with R12, as original, or has it been modified to take R134?

The fittings, and therefore the gauge sets, are different for each.

I have no specific recommendations of gauges, aside from "flea market," which is where I have gotten all of mine. I can't see paying close to a hundred clams for a set of gauges, when I can buy a good used set at a flea market for 20.

- Eric

rustyroger

You could just have your system re-gassed, over time A/C systems will gradually lose pressure, four or five years between recharging is ok.
The best way to stop it leaking and keep it in good shape is to use it!. The lubricant stays mixed with the refrigerant and helps keep the seals supple. Run it up every month, even in winter is what I would recommend.

Roger.

rocketraider

Starting about 1971 factory systems were engineered to run the compressor in Defrost. Twofold advantage- 1) dehumidified the air going to the windshield and 2) ran the compressor during off season.

You can also do this on 68-70 cars that have a compressor hold-in relay. Start the A/C system which locks in the compressor and then switch to whatever outlets you want. Compressor will run until you shut off the engine and you get the benefit of dehumidified air for defrosting.

dredluxx

hey guys, sorry i've been MIA. Very busy these last few weeks.

To answer your question, it appears that it's been modified to take R134.

MDchanic

So you'll need a set of R134 gauges.

You'll also want to confirm that your pressure cycling valve (I believe that's what they were using in these years) is calibrated properly for 134 - most people just put in the new refrigerant and don't change anything else. It wouldn't be a bad idea to install a new accumulator, with R134-friendly desiccant, too. Your condenser may or may not be the best type for 134 (once again, I'm not familiar with these years), but will work reasonably well regardless, and you could change it later if you find it's not cooling efficiently enough.

- Eric

dredluxx

Is that something I can do myself, or does it have to be done in a shop ?

MDchanic

You can check it yourself - you put a set of gauges on it and read the pressure switch opening and closing pressures on the low side gauge.

I'm not certain what the values should be, but that information can be looked up on line.

- Eric