I am wanting to charge my A/C system in my 71, everything seems to be hooked up, and I can jump around the switch and cut the compressor on. The car has sat for 14 years so I am sure there is no freon in it at all. Now, how do I charge the system. Someone told me that I had to pull a vaccum on it and charge it that way. But I was wondering if that is neccesary to pull a vaccum. Can I just start adding cans??

You need to hook a vacuum pump up to the system and keep it running for quite a few hours to get any traces of air & moisture out of the system. Another thing to do before hooking up the vacuum pump is to pressurize the system with air and check for leaks. You will probably find a few seals that are leaking.

Pulling a vacum will remove any mosture from the system. If it as any freon in it it is probably R-12. The only thing you can buy over the counter is R-134a.

I would suggest that you find a local AC shop that can recover any freon that might be in it, pull a vacum and then recharge with the proper amount of freon. R-12 is preferable but 134a will work though not as efficentl and may leak throught the hoses due to their smaller molecules unless you put barrier hoses designed for 134a on it.

If the compressor is cycling then there is freon in the system.

Best advice is to do just as stated above. Go to a shop where they can evac the system then see if there is any leaks then start a charge. Best to do it this way. r-12 is too precious to let fly out in the atmosphere.

I have the charged the a/c on my 69 charger with r134a a year ago and its still working great. There are no signs of it leaking out yet. I changed the seals with the green ones and put in a new drier. I drained out the oil as best as I could and used the new 134a compatible oil. I used a harbor freight vacuum pump that hooks up to an air compressor.