Re: 97 explorer air conditioning
If the quart sized steel "bottle" is very cold you probably have enough freon.
In park, rev the engine slightly (1200 rpm) with the AC on medium - if the clutch on the AC compressor is not cycling off faster than about once every 8 seconds you probably have enough freon.
If you can touch the line going into the cab and the line coming out (to the "bottle") and they seem to be the same temperature you DO have enough freon.
The AC system cycles the clutch off when the low side gets down near 35 psia because that pressure will make it cool; if you have enough freon.
If you are low on freon the system cycles the cluch fast or keeps it off because the pressure is low to start with.
I have never put too much freon in because I never put ANY in unless I'm sure it is low. Too much can do some big buck damage.
The system cools best when it just barely enough freon.
If you do add freon - add only 1/4 can and then see if the "bottle" is cooler - if it is not cooler, STOP.