The A/C system is only capable of dropping temperature a certain amount. Humidity and ambient temperature both effect the temperature out of the vents. So for example it may be 97 degrees outside with a 50% humidity, then the vents may only blow out at 60 degrees. If it is colder out it would be able to blow out colder. Best thing to do is vent the car of the heat to make the A/C more effective and only run recirculate after the inside of the car is cooled down.

The other problem may be either the temperature actuator is receiving the wrong signal and not going to full cold or the door is hanging up. I honestly would start with parking the vehicle and running the A/C with the drivers window down 6 inches. Then, put a temperature sensor in the center vent and see what the actual temperature is blowing out of the vents and know if there is a problem. No one should be in the car while doing this.

 

As a result, it's been a while since the A/C has actually stayed on more then 5 or 10 minutes at a time.

You can feel the compressor kick in and out, and like I said the freon is supposed to be okay. What could/should I check?

Are you really SURE the control head problem has been properly fixed ??
When it's REALLY hot out and in, the compressor should be engaged pretty much continuously, I think, and there are a few things including the control head that would make it cut out. One is, I think, a high pressure switch which is supposed to cut it off if the pressure in the "high" line goes too high to keep it from "blowing up" if the line is blocked.

Somebody needs to do a complete test of the system, not just the Freon charge.

 

Some things to check off the top of my head:

Freon overcharge
Incomplete or compromised connection: clutch plug, other plugs
Damaged wire(s)
Pressure switch intermittent
Control head intermittent
Temp door not fully closing off heat
Air obstruction, either at cowling or on evaporator
Cabin air filter clogged
Low engine RPMs at high fan speed
Clogged or obstructed heat exchanger in front of radiator
Duct work leaking

 

Cabin air filter clogged

Do the 11's actually have a replaceable cabin air filter ?
I thought not.

 

It hasn't always been this way, but I don't know how long it's been. We had had the problem with the control head cutting in and out (documented here => http://www.automotiveforums.com/vbulletin/showthread.php?t=324015). As a result, it's been a while since the A/C has actually stayed on more then 5 or 10 minutes at a time.

Sounds like this problem, described in the PDF here:

www.imcool.com/articles/aircondition/AC_ControllersAreRepairable.pdf

I'd try this before I did much else, with the description "the control head cutting in and out".

RwP

 

Yes, this. Mine was doing it and I cleaned & graphited the area. Started doing it again after about a week. There is something better than graphite that I used and it has been trouble free for 4 months now.

 

If the compressor turns on for a few seconds, then off again, and then repeats like that, its a low charge.
Its an AC, theres only a few possible options if it still is actually cooling the air.

Take it somewhere else and have them take a look at it. A standard functioning AC system should drop the air it takes in about 30 degrees. So even when its hot, it should still pump out relatively cool air. Also, the refrigerant becomes less effective over time, usually the life is about 3-5 years, so if someone just stuck a new bottle or so every few years, it could be mostly bad refrigerant. Maybe have it drained, cleaned, and refilled instead of just recharged.

 

Also, the refrigerant becomes less effective over time, usually the life is about 3-5 years,

WHAT ??
First I've heard of that.
Could you tell us more, please ??

 

No cabin filters in the 'Bu as far as I know, but I was making a general list. If I remember correctly, behind the glove box there's some kind of place there to cut an opening and insert one, but I could be mistaken. It may have been only on earlier models, too.

 

Sometimes the air conditioner on my 2007 Malibu will start running cold within a few minutes - sometimes it blows hot air for a half hour. I've had dealers and other service give me air-conditioner checks every spring when I see it being bad, but now it is worse than ever.