A/C Question for you gentlemen

[Dancing Bear]

It's not on a Grand Prix, but a 3100 equipped 03 Buick Century

Intermittent problem with A/C system ... it works very well for first 15-20 minutes of driving. After this period, it will periodically switch from cold air to ambient temp air, almost like the system is shutting off. A/C light stays lit the whole time, and I don't hear the compressor shutting off. The warm air period has no consistency, sometimes it will only last for a few minutes and others it will last the entire ride home. At idle is when it seems to happen the most, when the car is moving it seems to get cold again.

Here's what I have done:

Cleaned A/C condenser with soapy water and pressure washed
Checked cabin air filter and removed all debris around air intake on windshield cowl
Checked A/C pressures in the system .. at 88 degrees outside with 66% humidity the pressures were 48 on the low side and 200 on the high side

My only idea is that it could be a problem with the fans turning off while the A/C is on, this causing the condenser to become heat soaked and kill the performance of the system. What controls the fan operation while the A/C is on?

Any ideas or suggestions are greatly appreciated!

[SubwayGuy]

Maybe just needs a recharge.

[ericspecullaas]

it sounds like the pressure is dropping. i would hook up gauges to it and see whats going on. if the pressure is dropping then you need to add some more freon.

[Dancing Bear]

I hooked up my gauges this morning to check the pressures, I posted them up above. I left them there for a good amount of time while I worked on other projects, the pressures only changed slightly (less than 5psi on either side) I'm no A/C expert, but I was under the impression that the system had the correct refrigerant level if the pressures were okay. Is this incorrect?

[ericspecullaas]

so the car was off when you checked the pressure?

it you ran it with the gauges on it that give a better reading. once the car turns off the pressure goes up.

[Dancing Bear]

Car was running when I checked pressures, A/C on full blast

[ericspecullaas]

i would look at your blender doors. remove one and set it to full cold im thinking that the blender door is having a mind all of its own.

[Scottydoggs]

whats your outside air temp thing reading? if that sensor is bad it says its not the right temp and the a/c quits working.

[Dancing Bear]

Hey there Scotty! I don't believe this Buick came equipped with the outside air temp sensor, It's a pretty barebones model. It doesn't have it on the rearview mirror like my GTP does.

[Scottydoggs]

fudge, its a century, lol if you have it it would be in the digital climate control. not sure if you got knobs instead or not.

[Dancing Bear]

Lol nah its got the regular temp sliders and knobs. Thank you everyone for the help, I found out what the issue was! Apparently at some point, the knob had fallen off and my mother placed it back on. When she placed it on, she set it to vent instead of Max AC!

I switched it back to the way its supposed to be, and checked blend door operation, everything is well! A/C has been blowing ice for 20 minutes now. Thanks again peeps!

[CrazyGuy03]

Being its a sealed system , it should never need a "recharge". If you are leaking refrigerant you need to fix/repair it
if there is a leak you will have low pressure , and low pressure safety switch will trip
if you have a plugged or blocked condenser , poor air flow or faulty fans, the head pressure will rise and trip the high pressure safety switch.
That could cycle the compressor on and off while in use

[ericspecullaas]

uhh he fixed it sally. silly girls trying to help