[flybouy]

"Back in the day".... Several decades ago (before the ramifications of R-12 were highlighted) we (DW & 2 young daughters) were about 3 hrs from home on a sweltering August day. About 97° F and 90% RH. The a/c on the 1985 Pontiac Perisian started blowing warm air. I pulled off the highway into the parking lot of a shopping center that had annoutparts store. Told the DW to take the girls into the pizza shop next door for a bite and cold drinks.

I bought a cheap a/c recharge kit and 4 cans of R12. Refilled with 2 cans and checked and attempted to assess the situation not having my hose and gauge set with me. Drove about 2 hrs and had to pull over and put in 2 more cans that kept us cool until getting home.

Point is the refrigerant was leaking out. Simply replacing it doesn't fix the leak. Unlike the cooling system for the tow vehicles engine an a/unit is a sealed system. In a vehicle engine cooling system it's an open system. The radiator cap controls the pressure by venting it to a "coolant recovery tank". If you continue to drive while it's boiling out then the volume will overcome the tank and you will have a loss of coolant.

As an a/c system is a closed loop the only way for it to be low on refrigerant is via a failure in the plumbing, a leak. Leaks don't fix themseves so adding more refrigerant doesn't fix it. Just want to make it clear so someone's first experience doesn't end up with a "but I added refrigerant last week and now it's not working again".