Air conditioner not cooling ...I could find no leak and added freon, but cools some on drivers side but not on passengers side.

https://www.youtube.com/watch?v=mS56WnGUSTU

https://www.youtube.com/watch?v=--SCk_gHM4o
This problem is a low freon charge in the system. ... But a system that is 1/2 pound low will cause the passenger side vents to blow cool or cold air, and the drivers side to be less cool or even warm on this car. There is simply not enough freon capacity in the system to cool the air to the drivers side. https://www.justautorepair.com/buick/century/cool-passenger-warm-driver

The 2 vents on the drivers side have warm air blowing out. ... But a system that is 1/2 pound low will cause the passenger side vents to blow cool or cold air, and the drivers side to be less cool or even warm on this car. There is simply not enough freon capacity in the system to cool the air to the drivers side.
https://www.justautorepair.com/buick/century/cool-passenger-warm-driver

Chances are you have a pretty fast freon leak, and the passenger side will be blowing warm within a few days. I have the same thing happen on a couple of my GM cars, except my leak is very slow; warm driver's side, cold passenger side.

You can try and top off the freon again, but I suspect you're going to have to take it to a shop to find the leak and get it fixed. Plan on spending some big dollars for the repair.

Good Luck.

When self adding freon after it leaks out you get air trapped in the system. After adding freon a couple of times the air expands not leaving room for the needed freon. To continue adding freon with air tapped will knock the compressor out pretty quickly, there's not enough room for both & the air is keeping the freon from being able to cool properly give the false indication of being low on freon. The freon you are adding has the dye added to assist in finding the leak since freon does not evaporate nor dissipate it its being leaked out. A black light will assist locating the leak. The best thing is to have the unit checked & serviced by a mechanic...he'll charge about $ 150.00 to check for leaks, remove the old freon...his machine will tell him how much air its trapped in the system by how little freon is removed. For the service fee he will replace valves & gaskets, where needed, correcting most leaks. After sucking the system down & recharging the problem should be corrected.

unfortunately this always seems to be due to the system low on freon. it feeds freon into the pass. portion of the evaporator core first so when it starts to get low you lose cool on the drivers side first. I would go ahead and have an ac service performed and dye added, that way if it goes low again the leak can be found with a black light that illuminates the dye at point of leakage..

either your R134a is leaked out ore you need add and also add a dye see if leaks.
Add to the low side the car while running with gage with ac cranked on high follow metter dont over fill it loc the ac up. Easy 20 minute job wallmart sells the gage and R134s and so do auto zones

You may want to have the evaporator (the AC part under the dashboard on the passenger side) cleaned. It needs to be taken out and cleaned. Normally this would solve the issue. Have the freon checked if there is a decrease. You may have it filled up and have the system checked for leaks.

If you have dual climate control, you most likely have a low freon level. The evaporator can get cold enough for the passenger side (where the evaporator is located), but not cold enough to transfer cold air to the passenger side. Have it inspected for a leak and the freon level topped off.

How much freon does a Buick Century limited take.

sound like you have a diverter valve some where in the unit that is not switching the air flow as it should. sometimes just playing with the controls back and forth may free it up. If not then you will have to go into the vent system and find the valve that switches that function. Good Luck