Do not convert to R-134a. The change is fraught with pit-falls and traps and the system will be a disappointment when it is done. R-134a is a good an idea as alcohol in motor fuel. (Yes, it is that bad.)
Do you have a good friend that can deal with A/C?
Buy him:
A case of HC-12a (Duracool)
2 cans of leak trace HC-12a
1 - Cheap LED UV ligtht and a pair of yellow glasses.
Have him put in the leak trace and enough HC-12a so the compressor runs and then run it for a while. When the dye shows up, fix that part and now suck down and recharge with HC-12a. This will take some calculation as it takes much less of the HC than it did of any prior.
I sold off my last big can of R-12 years ago. I will never buy R-134a again. HC-12a works better, is compatible with everything (none of the oil and seal issues as with 134), and it is Cheaper.
The only issue is locating it, but it can be found on the web without much difficulty.
Matt
