I have a 67 SS/RS convertible that is a factory air car. Last year I converted to R134a, rebuilt compressor, etc. Car has never cooled properly. "Experts" tell me that R12 systems have conical fittings and operates at a lower pressure than R134a. R134a systems have o-ring fittings to accomodate the higher pressures.
Bottom line is can a factory system be converted to R134a and cool properly without eventually leaking out the R134a thru the conical fittings or does the entire system need to be revamped with the proper fittings?

 

Change the filter-drier.
Drain the compressor oil and recharge with 134a compatible oil. (PAG or Ester Oil)

Insure that the system is clean and free of contaminants (Depending on component condition, this may be a simple matter of blowing out with compressed air or liquid flushing with an air-conditioning flushing agent)

Replace all rubber hoses with barrier hose. (R134a has smaller molicule)

Install 134a charge port adapters.
Send POA valve in to be calibrated

Charge with 134a between 70-80% of the original R12 charge amount.

Replace any o-rings with 134a compatible.

Ignore the sight-glass. A properly charged 134a system will likely show bubbles in the sight-glass.
Typical 134a charge rate will be approximately 70-80% of the factory R12 charge amount.

 

Thanks. I think that all that has been done though not sure about the hoses. I'm told that I need a different condenser since the original style has round tubes and new style has flat tubes for better dispersion of heat. All I know is that I'm getting very frustrated to the point that I may try to go back to original and try to find R12.

 

If converting to R134a becomes too much of an issue for you, you may want to consider refrigerant Freeze12, which is a EPA approved direct replacement for R12, and the price is pretty close to R134a. It is compatible with all the R12 hardware, and hoses, so that nothing needs to be replaced if it is in good condition. However, it requires that charge fitting adapters be used to indicate that the system is using Freeze 12. I have used the stuff on several old cars, and it seems to work properly.
Freeze-12 Refrigerant, EPA Approved R-12 Replacement.

 

I remember when right before R-12 got phased out, the stores had the cans for $.99 each to get rid of it.
Looking back, I should have grabbed up all the shelves and saved them as a nice little retirement fund!

 

Just a FYI the pressures themself are not the real reason for the Oring swap. The original o-ring and connection should be good to 250 PS1 with a saftey factor of 2. Meaning they should not blow till almost 500 PSI. Your hardware will blow before the conncetions. The reason for the O-ring and hose replacement is because the molicules are smaller and will blead thru the orignal R12 stuff. I did not say might, I said it will. What is your problem? Are you losing product or is not working good enough?

FYI guess what the 3rd largest illegal substance that crosses the Mexico border.... R12.

 

most a/c compressors are compatable, but when converting to r134, you may need to replace compressor with a r134 compressor also.

just a thought...

 

If you reconfigured the POA valve and the pressures are right its not a compressor issue. If the compressor will not pull the low side low enough and the system is not overcharged then you have a compressor issue.

 

Thanks for all the insight. I'll do some more exploring on this R12 substitute but I do have 4 small cans of R12 that I might try to start.