AC weird problem. AC professional can't fix it
 

Hi
When it's about 90F and over outside my AC will work for 4-5 min. then blow warm air for couple minutes then go back to cold air. It's been keep doing like this all the time while I'm driving?
What is wrong? I paid $40 for check up and they don't know what is wrong with it. They told me if the problems becomes an everyday issue to come and see them. I thought it might be a thermostat?

sounds like the evaporator is icing up, could be a blockage or bad expansion valve.

I try to recharge the AC using AC Pro from autozone. I have overcharge it and then the AC won't turn on at all. After talking to autozone salesman he told me to release some of the freon. It did help but since then the problem occurs. Did I messed up something because of that?

What year is this car?

It is 08

Yes, you messed up. Likely the original problem was faulty AC relay or excessive clutch gap intermittentaly disabling compressor circuit.

Your best bet now is to find some good professional help (not the shop you tried!). check Angie's List or other sources for good auto AC help. Expect to pay dearly.

good luck

So, is the ac working at all now?

Yes it is working. When its below 90F outside it is working all the time but when the temperatures hit over 90F it blows cold air for a while then hot air and cold and hot....

Might check for codes on the HVAC unit.

Turn the key to on(II) from off (0).

Press and hold the OFF button, then within 10 seconds press and release the REAR WINDOW Defogger/Mirror Defogger button five times. Release the OFF button.

From there if there is an issue the temp will light up all of the segments of the temp display and either or both the AC and Auto AC will light up. From there the "code" will display, note which segment of the temp displays and which light (Auto or AC On) is on.

Let us know what you find.

Could be a sensor or blend door motor causing the issue.

You may be overcharged now and when system temps increase, the Hi pressure cut-out switch is opening the compressor.

do you intend to repair yourself?

good luck