Hey everyone, this one has me stumped so need some help from the third-gen experts.

AC stopped working in my 87 IROC-Z. I bought one of those cheap parts store recharge kits 2 years ago, and since then I've had ice cold AC. I always assumed I had a slow leak and I'd have to fill it every year, so after 2 years I counted myself lucky. So I went and bought another bottle and filled her up. Throughout the entire process, the compressor never came on, and the car never got cold.

So the next thing I did was jump the switch behind the accumulator, and bam the compressor comes on. Almost immediatelI have nice cold air but I shut the car down as I'm not sure leaving the compressor on the entire time was a smart move. Hooked everything back up normal, and again back and square one where it will not come on.

What would be the next step, or the likely part I need to replace?

Thanks guys!

EDIT - Would this be something I should replace?

http://www.rockauto.com/catalog/moreinfo.php?pk=514408 - ACDELCO Part # 1550369 {#89057829} SWITCH,FAN CONT A/C REFRIG PRESS 2 TERM; Engine VIN H

 

 

Thanks Nina, the kit I bought had a gauge set, however how accurate it is is something I don't know.

However, I think it was actually a post of yours I searched and I found the car takes a little over 2lbs...which according to the companies website equals around two cans, which is what I put in.

When I jumped the compressor, it was showing 30PSI on my gauge (from the connection on the accumulator).

 

Okay, I think I'm going in the right direction, but there are still a few issues.

I decided to go with my gut and replace the switch behind the accumulator, and it appears I was right, partially. Compressor now works when I switch on the AC, but it will not turn off. When the AC is ON, the gauge shows 50PSI on my gauge (right at the top of what they consider to be the "green zone"). It DOES NOT cycle like it used to (click on and off every 30 seconds).

The one weird thing though I noticed by accident, it DOES shut off if I turn the steering wheel a bit (noticed this in idle as I got in and grabbed the wheel for support). If I turn it a bit and "hold it" in a certan spot, the compressor stays on. Odd.

So...I have AC that works, but my compressor runs non-stop...? I'm not sure if that's an issue or if it's bad for the compressor, so thought I would ask before I use it too much.

 

 

Another update, I let out some pressure (this is the non-ozone depleting stuff, don't worry eco-people), and it appears to be back to normal...almost. Compressor now cycles, but a bit too often for my liking so I think I let out a bit too much. I will top it up and all should be good to go.

So, for any of you in the same boat with your compressor not working (or staying on), there is a good chance 1) your low-pressure side switch is faulty 2) your system is overcharged.

 

I was going to mention that these cars need a new low pressure switch after being retro fitted to R-134a, but if it's working you must of got the right one.

I'm an automotive tech and I just want to point out that you can't charge a R-134a system by pressure and have an accurate amount of refrigerant in it. The only way to do it is by weight. But if it blows cold and your happy with it then no big deal.

Also, even though it's not ozone depleting it is illegal to release R-134a into the atmosphere. Infact it's against federal EPA law to service an automotive AC system unless you have a 609 card. Anyone can buy it but legally a certified technician is suppose to service it and have a recovery machine on site to be totally legal. But like a lot of things, no one's going to see what goes on in your garage so who cares about the law lol.

Sounds like yours is back to normal but I just like to put some of this stuff out there for others that might read it. For people not familiar with ac and who don't have access to the proper equipment I strongly recommend biting the bullet and paying to have it diagnosed and serviced. That way you know it's done right and you have the right amount of oil and the right amount of refrigerant to carry that oil.

Also don't buy the cans with sealant in them, you'll be lucky if you don't end up replacing the entire system.

 

Well there is a way of charging it without a scale, but you need alot of charts and one hell of a accurate manifold gauge setup.

Btw there's a lot more to a proper running system. Having a machine vacuum a system eliminates the moisture that usually wrecks a system. Also one thing to remember, if the system was ever open for a while, you should change the accumulator. 9 times out of 10 the desiccant (like the little packed you get in the shoe box that your not supposed to eat) in the system is shot (cuz the car is about 20 years old usualy and isnt really compatible with 134a)

Hey but if it gets you through the summer for a few bucks, that works.

 

I should point out the stuff I bought was R12A, not R12, or R134A. Stuff you buy on the shelves at the parts store in the kit with the gauge. I use the AC maybe once or twice a year...so at this point spending hundreds on doing it right isn't high on the "car-to-do" list.

Anyways, I messed around with it some more, and I'm stuck with one question. Should the compressor stay on with the AC, or should it cycle? What I did to stop it from staying on all the time was let out just enough so that when the compressor is running, it cuts out at 29PSI. Pressure then builds back up to 40-50PSI, and the cycle repeats every 20-30 seconds (at idle). At speed I can't tell due to engine/window noise. The only thing though, is that it doesn't feel as cold as it used to. Compared to my 83 Z28 (which I did the same way, 2 weeks ago), the 87 is probably 10 degrees (I compared the two back to back to check where my pressures should be).

Maybe it's time to suck it up and realize I have a 25 year old AC system that probably needs to be replaced.

 

On thirdgens it should cycle on and off just as your described. Also the interior temps will always be affected by multiple things, Condenser condition, orifice tube condition, and also, if you car has t tops or a convertible etc. Stick a thermometer in the middle vents and set it on low blower fan setting and see what the temp is.

45 degrees is about right for our cars withough a full blown 134 a retrofit, (compressor, condenser, core and accum.)

Sounds like you got it working good.

Also, remember on a 100 degree day with 80% humidity, ac's struggle to cool down cars. but on a 100 degree day with 0 humidity, they work like a champ.