You shouldn't have to change freon, it doesnt go bad.
1993-95 for most.
Why do you want to change the Freon? Not necessary and very expensive.
There is no freon in a home sprinkler system.
Never
Why would you want to change the AC freon? Buy a kit at Wal-Mart or auto parts comes with instructions
It was a bad answered that talked about changing the antifreeze -- not the airconditioning freon.
Freon does not generally need to be replaced. However over time, systems sometimes have a small leak and need to have coolant added. A Freon gauge can confirm if you need to have Freon added.
ding freon will make it colder, only if freon is low. if freon is low you have a freon leak so adding will be wasting time and money. more likely to need a new ac temp thermostat, which is no big deal to change
1994-95 timeframe
To change the refrigerant in a Buick Rendezvous you will need to remove the old freon. Freon is bad for the ozone, so you will need to hook to a special machine and reclaim it. Next you will need to pull a vacuum on the ac syatem, then fill with new freon.
Some started in 1992 but most all started in 1993...........