Originally Posted by mactripster
Thanks for help. How does one determine if the A/C is using R-12 or R-134 refrigerant?
Ask someone who is familiar with A/C systems before you chance injuring yourself. R-12 fittings were the older style and I believe both fittings had the same threads. It was possible to hook up a high side hose to a can of freon and cause it to explode. R-134 fitting are more user friendly and on my coach are of two different sizes. I personally use the old gauges with the adapters on them. In either case, you can do some serious injury to your eyes with freon escaping. You need to make sure the lines from your gauges to you onboard fittings are purged of all air by running some freon through them when ready to attach. Air conditioning systems do not like air. My coach system holds 4 lbs of freon and the only sure way to get the right amount in is to evacuated the system put it into a vacuum and check for leakdown. Then, if no leaking, you can add the freon back into the system.
"One problem with can charging is a misunderstanding as to what is meant by 1 pound of refrigerant. Many technicians today still speak of 1 pound cans, which have not been produced since the late 1960's. The industry also saw the use of 14 ounce refrigerant cans until the mid-1980's. Today when we speak of 1 pound of refrigerant that amount is equal to 16 ounces. When we speak of 1 can of refrigerant that is an amount that is equal 12 ounces."
Also, R-134 is not as forgiving as R12. You need to be very close to the exact amount to get the best cooling from your system.
You can buy the cans at auto parts stores or walmart and also the charging hose but do some research first and be sure you understand what you are doing. You can do a lot of compressor damage and more important some damage to yourself if not careful. Good luck and let us know how it works out.