a/c question on 1990 Chevrolet Camaro

how many 12oz cans of 134a refrigerant should be added to a a/c that needs recharged after sitting for a little over a year. was recently converted over from old unit not long before it sat. no known leaks worked and blew really cold before it sat think it just needs recharging how many cans would u recommend? (its actually a 1989 camero with 2.8 V6)

Asked by for the 1990 Chevrolet Camaro
3 answers 4 comments
what about evacuating and vacuuming down the system , or did I miss something?
Kids now days
How much is still in the system.
I don't know it just blows regular temp. air not cool at all so I thinks its empty
Wow, fool proof; That's a big crock. A retrofitted r-12 system should only be charged 80% of the total charge the r-12 system calls for, and a single gauge on those cans are not fool proof. The only way to do it right, with the ambient temp below 80deg is to remove the existing Freon, and refill with the proper amount, and you need both gauges to see if it is working properly with the head pressure.
If you are doing this as a DIY project, buy the kit with the pressure gauge on the hose. Fill the system until the gauge reads full. It's pretty well fool proof. The only way to know where an A/C system is in the way of charge, is with gauges.
ok cool thank u