I have a 91 corvette, jut bought it in the fall. When I bought it, it was cold, so the A/C was hard to check. I did confirm that the compressor came on, and the accumulator was sweating, so at the time it appeared to work.

Well now it doesn't. The compressor does not come on at all. I pulled to codes from the electronic climate control, and it shows low freon.

I don't know how bad the leak is, but I'd like to start by charging it and seeing how long it will last, but I don't know if it's R12 or R134.

How can I tell the difference?

I thought that the R12 system would have the old style fittings (with screw threads). Mine care has the new style (kind of a push on fitting, no treads). The fittings appeared to have not been converted with an adapter, instead, the accumualtor and the a/c line looked original (i.e. maybe the dealer did it with new parts). However, if that was true, I expected to see a sticker, showing the conversion. I did not see any sticker, except for the R12 sticker near the blower.

Maybe I'm working on bad assumptions and the fitting style means nothing. Or is it possible that someone put in Duracool, and only had to convert the fittings.

I think its been converted based on the fittings, but I'm not sure if that is a good measure, or if there is another way to tell.

Dale

 

Vacuum the system and install the 134. Add an oil shot. A lot of times slow leaks can be at fittings. Leaky fittings will collect dirt residue. Good luck.

I vacuumed out the r-12 and put the 134 in 4 or 5 years ago. No issues since.

Mike

 

In a perfect world there would be a sticker saying it had been converted, in the real world anything is possible. There are refrigerant analyzers available but if the fittings are 134A style I would recharge with that refrigerant then test for leaks, good luck.

 

Open the hood and look behind the wiper fluid tank, on the round black box (don´t know what it´s called) behind the tank there should be a sticker with what the AC contains.
Ask a AC mechanic what kind of check valves a R12 or R134a system should have.
At least one of the (high or low side) valves is different (comparing R12 to R134a).

I had mine checked and repaired (O-ring at the electrical connector) and filled up with so called Freeze12 from an E-bay-er.
The set came with 3 cans of gas, one can of oil and a set of hoses and connectors.
Mine is a R12 system.

I had an industrial cooling service company do mine here in Sweden.
Just know what you are doing, the best is do some research on how to empty the system (mechanic should know how to), and don´t forget at some point to take away the neg. batt. cable to reset the computer.

We could not get the compressor to engage after finishing the fill-up.
Re-and connecting the neg. batt. cable fixed that, probably to erase the fault code that was still present in the C68.

 

I was all set to vacuum it and install new R134A, but then I checked the pressure with a gauge, and it was actually a little on the high side.

I started checking a few things (low pressure switch, high pressure switch, etc. All had continuity (which is correct). I then broke out the owners manual and start following the troubleshooting tables for the 09 code (09 read from the electronic climate control head). It states to first disconnect the battery cable, since connecting the battery cable with the ignition switch in the on position can cause the control head to be confused. I considered skipping that step since it sounded like BS, but I didn't. I disconnected it for 1 minute, reconnected and all works. No codes and AC is cold.

I did remember that over the winter, the battery died when I had the trickle charger on 6v instead of 12 (somehow it got changed). When I recharged the battery, I'm not sure what position the ignition switch was, so that may have been what caused it to generate the code.

Dale

 

The three kisses of death for this year:

1. Running at high temperature.
2. Synthetic oil if running on the original engine.
3. R134A.