Scoured the service manual, repair guide, google search and threads. Maybe this is the easiest way to get simple answers to simple questions.

My system works but the compressor cycles on and then off too quickly. It is low on "fluid". In all my experience I have added a "can" or two until the cycle rate and duct outlet temperatures fall into line and then everything works again. My IROC's system likely has never been serviced so I am fairly sure it does not have any leaks since it still works after all these years.

1. Where is the low pressure port (I am pretty sure I know)?
2. How can I tell for certain if my system has been converted to R134a?
3. Do I just add a "can" or two of R-12? What is all this chatter about adding oil then freon? I have a bunch of the old-school R12 cans. This is all that I have ever added to cars using R12. I have never added just "oil" or "freon". What am I missing?

 

Look at your fittings. If they are QD Type, its been converted. Screw on type is R-12
Low pressure port is on the Receiver/Dryer. High Press port is on the SMALL line

Use gauges to bring into spec according to the chart. Ambient outside temp/Pressures

 

Awesome, thanks. I just add good old "cans" right? none of this oil vs freon juggling?

And so according to the chart, if its 85 outside, I should add R12 until I see a low side pressure of 91.8 inches or 45.1 psi?

 

If you want to add some oil, it wont hurt. The R12 may have it in with the freon depending on what you have. Did you determine what freon you have in it?

Correct. If the system hasn't been broken into, no oi should be necessary

 

Chances are if your freon level is low/empty, adding more freon will probably also escape the system. A proper AC system will not leak.

A proper repair means evacuating what's left of the freon that's in the system but you probably won't be able to find anyone willing to touch R12 any more. Once the system is evacuated, it's pressurized with nitrogen to look for leaks using a soapy water solution. Common leak points are compressor shaft seal, compressor inlet and outlet port seals, any part of the rubber AC line especially where it's crimped to the metal tubes. Your evaporator and condenser could also be cracked and leaking but those are usually more obvious. If a soap bubble test can't find any leaks, the system can be recharged with freon then a freon sniffer is used to detect the small leaks.

Once any leak is repaired, the system is pulled into a deep vacuum to remove any condensable gasses and the system is recharged with freon. It doesn't take much to do the R134 conversion since R12 is now illegal to use and 2 pounds of the stuff will cost you an arm and a leg.

 

yeah, I'm assuming it hasn't been serviced in years. So I'm thinking its on the borderline as far as levels. But no unusual leaks. Just a slow 15 year bleed down. I will sacrifice one can and see how it goes.

 

So I checked it and it has a QD fitting on the accumulator but the high side connector on the small line running next to it is still a screw on with a schrader valve. The high side, small line, was leaking when I took the cap off so I have to get that fixed. Any idea if its R12 or R134a? Any way I can tell?

 

Take a picture. It's probably R12.

 

I have seen a few guys charging a R12 system with compressed can air. AKA keyboard duster. Just an idea.

 

There is a schrader valve deeper inside in the low pressure coupling with the threaded inner race.

 

The fitting on the Dryer is R134 and if you move that foam on the High side, you'll see that the fitting is actually screwed on the dryer.
My guess at 99.5% is it's been converted.

I converted my 88 and 85 last year.

 

Ah, ok. So the high side fitting is a QD male?

 

Yes

 

Awesome, thanks very much. So last question, how do I repair that leaking high side schrader?

 

If you can take the cap off and take a awl or nail and quickly tap the needle in the schrader to depress it, it may seat, or get worse. I've had good luck seating them that way. Put gloves on though....it kinda cold!

Or unscrew the R134 fitting and put a new one one. You wont lose anything due to the schrader in the R12 fitting...just a quick pssssst.

 

Awesome. I did tap on that schrader with no luck. It just kept leaking. I bought a small kit with two schraders and caps at the local auto store. Along with a can of "high mileage" R134a! Will report back to close the loop. Thanks again.

 

So update. The schrader valve in the high side port is larger diameter than a standard schrader. My schrader tools wouldn't fit over it and the port was part of the line. (I did try and twist it gently with some pliers but it's not screwed over another port. So I need to have the system evacuated to repair that larger schrader.

I'm thinking now I have an R12. Maybe the previous owner put an R134a QD on the low side to charge it? The high side looks like factory I think.

 

My car is the same way, it has the new R134 fitting on the low (light blue) side, but the older R12 style on the high side. My compressor shows a sticker saying it was re-manufactured, so surely at one time the car had the freon drained and replaced. My guess was somebody swapped the car to R134 and just didn't bother with the high side conversion, so seeing this on another car is confusing. Hopefully somebody has some answers here