Air Conditioner Advise

[TX '90 ZR1]

A/C repair & service is not my strong suit, but I do know enough to ask before screwing something up!
A few days ago the AC decided to stop cooling and the indicator light started blinking. Checked codes. Code 9 showed up which is low freon. First thought was a leak and sure enough found the high side schrader valve was leaking. Gave it a little tightening and do not detect any more leaking.
My dilemma is in trying to figure out if it still has R-12 or R-134. The pressure switch is marked R-134a, but the fittings on both high & low sides are R-12 connections.
I suspect it has R-134 in it as I have been able to determine the AC was inop in 2014. I was able to track down and talk to the shop that diagnosed it, but they did not perform the repairs. Have no info on where repairs were done.
If it was converted to R-134, would not the fitting adapters still be in place? It has been my experience the schrader cores need to be removed to install the R-134 adaptors. True?
The AC is working again after clearing the code. However, I suspect the system is right on the verge of being too low to operate properly and would like to charge it up to specs.
As an aside, I have information showing Henderson Performance installed an AC pressure switch in 2016. Nothing else in their records about AC work.
I'm open to suggestions as to what you would do.

[WARP TEN]

You might want to give Marc Haibeck a call. He has a lot of experience switching ZR-1s to R-134. Not a big deal to do it but I don't know about the specific details of what physical changes are visible afterwards.--Bob

[spork2367]

Originally Posted by TX '90 ZR1

If it was converted to R-134, would not the fitting adapters still be in place? It has been my experience the schrader cores need to be removed to install the R-134 adaptors. True?

Nope. Some people leave the adapters on, but on my personal vehicles, I never do. I've also swapped hoses on my gauge sets to do systems without the adapters.

[TX '90 ZR1]

Thanks Guys.
I've got a buddy pretty close that is a lot more up to speed on A/C than I am.
Think I will pay him a visit and see what he thinks is the proper way to proceed.
As always, thanks for the feedback.

[jss06c6]

The compressor and accumulator should have been changed to switch to 134. The form factor on the 134 compressor is the same as R12, but might have a sticker on it indicating R134. Worth a check.

Is the low side connection also R12?

Sent from my XT1585 using ZR-1 Net Registry mobile app

[Ccmano]

I’m not saying it’s right to do this but you can change the R12 system over to R134a by simply changing out the oriface tube to the R134a version, using an oil that is compatible with R12 and R134a and evacuating the system. Then recharging with R134a. I know this works because I’ve done it. How long the system will hold up is another question. Ideally the compressor, dryer/accumulator, expansion valve and seals should be replaced too. My point is that it may be difficult to determine what is in the system. I suppose the configuration of the oriface tube should tell you. I’m not sure if today’s leak sniffers are specific to refriderant type.
H

[TX '90 ZR1]

Originally Posted by jss06c6

The compressor and accumulator should have been changed to switch to 134. The form factor on the 134 compressor is the same as R12, but might have a sticker on it indicating R134. Worth a check.

Is the low side connection also R12?

Sent from my XT1585 using ZR-1 Net Registry mobile app

I have searched high & low for any stickers or clues. The pressure switch does have a 134a sticker on it.
And yes, the low side has the R-12 connection.
I tend to believe that is has been upgraded, but can not be sure. The shop that checked it out in 2014 said the compressor had a seal leaking as well as a couple of other places leaking. However, the owner at that time did not have them do repairs and he has since passed so I am unable to verify how it was repaired.
All part of the joy of owning a fantastic vehicle!! (I really do enjoy checking it out and making sure things are right)

[TX '90 ZR1]

Originally Posted by Ccmano

I’m not saying it’s right to do this but you can change the R12 system over to R134a by simply changing out the oriface tube to the R134a version, using an oil that is compatible with R12 and R134a and evacuating the system. Then recharging with R134a. I know this works because I’ve done it. How long the system will hold up is another question. Ideally the compressor, dryer/accumulator, expansion valve and seals should be replaced too. My point is that it may be difficult to determine what is in the system. I suppose the configuration of the oriface tube should tell you. I’m not sure if today’s leak sniffers are specific to refriderant type.
H

The conversion you describe is what we did during the big hubabaloo of the change over in the mid 90's. Never had a problem.
To my knowledge, the sniffers are not specific to refrigerant type. At least mine is not.
Just trying to do it right. I'll figure something out.
Thanks for the input.

[-=Jeff=-]

I will say that with a higher head pressure of R134a, I had noticed a higher drag on the motor. This was on my 1990. I have since added a parallel flow condenser and switched back to R12, Blow cold, but no real volume. but the volume is the design of the ducts and system in the car.