Identifying R134 AC Conversion
 

Is there a way for me to determine if the AC in my 83 SC has been retrofitted with an R134 update?

If it was done around here the fill valves are a different size but I doubt that is required to actually make the change to r134.
I don't know if gas is available in fill cans with same valves a r12

If the system was "properly" converted to R134a there would be a blue colored sticker in the engine bay noting the amount of refrigerant, type of oil, whom did the conversion and when, and there would be R134a charge port adapters over the original R12a schrader service ports.

One simple way to determine what the refrigerant 'might be', assuming we are discussing R12 service ports and R134a service ports, is that an R12 service port has threads on the outer diameter, whereas an R134a service port has threads on the inner diameter.

When it comes to the size of the R134a service ports, the larger port diameter will be the high side and smaller port diameter will be the low (if they were properly attached). The color of the caps could be black, grey, red, blue, or whatever, but usually you will find Red on the high and Blue on the low.


Here is a pic of stock York set up for R12. Inside of the Red square is the original R12 service port. There is no R134a adapter attached.


http://forums.pelicanparts.com/uploa...1404315127.jpg


Below is 84-89 911 with a Denso. The red colored cap is on the R134a high side service port adapter and the Blue cap is on the R134a low side service adapter.
http://forums.pelicanparts.com/uploa...1404315204.jpg

And, below is a Sanden type compressor with a red cap on the high side R134a adapter and a blue cap on the low side adapter.
http://forums.pelicanparts.com/uploa...1404315315.jpg



Read the Mr. Ice Project

Maybe look for a high/low electrical switch on the dryer?

The stock system never had a pressure switch. Some earlier models had a 'heat sensor' screwed into the drier;
temperature on the high side correlates to pressure however a low high pressure switch is more functional and
accurate.

Well, what I meant is that if it has a high/low switch - it should be R134. Is that correct? The dryer that I pulled off of my '85 did not have any switches, etc.

You are certainly the expert - not me!

Not necessarily.
You can have a system with a pressure switch(s) or heat switch and it can have any approved alternative refrigerant or R12, OR you come across systems lacking a pressure(s) or heat switch and find it may have any approved alternative refrigerant or R12; its preferred to have a binary low high pressure switch installed.


The original question in the post asks how to tell if a system was retrofitted to R134(a).
The way to identify what is in the system, assuming the system is in compliance with SNAP, is look at the service ports and look for the refrigerant identification sticker.

Thanks Charlie. I am sure that you have seen it all on these cars...

I'm pondering if I have seen to much, lol.
Enjoy your July 4th Holiday.

Griff