Texas993

I remember a string posted earlier this year, but searched to no avail.

My AC has been serviced recently and the freon levels are fine. Service done at the dealer by a great tech. No fault codes. System works flawlessly for the first 20-30 minutes, then starts blowing ambient temperatures.

The dial is set to max cool. If I push the Max AC button, nothing changes. The compressor seems to be running. Shutting down for 5 minutes helps. It will cool normally again. It behaves like this in all humidity levels (5% - 70%) and temperatures (80-100's).

Any help? I remember someone saying there is a sensor in the evaporator (?) that they move.

tjhcom

See 'a/c blower motor' post from earlier today -- one response by 'mlincoln' in this post includes a number of useful links.

Texas993

tjhcom, thanks for directing me to that string.

But that does not seem to be my issue. My blows out of the correct vents, and does not increase or decrease. It simply stops blowing cold. Like something is freezing up.

I remember a post about it from a RLer in Florida. And he determined that something froze due to the humidity. Wish I could find that string.

Bull

Don't know if it is your problem, but i have seen room style AC units freeze up and stop functioning when set to very low temps in hot, humid weather. The solution there is to set the temp higher. Most AC units can only lower the temp 15-20 degrees max.

cabrio993

How much pressure is in the system? If the system was "overcharged" the compressor will shut off to avoid over pressure on the high pressure side. Can you ask the tech for the PSI or BAR readings from when he serviced the A/C?

kkim

I believe the issue was that the evaporator was icing over and at that point could not cool further due to ice blocking the cooling passages and the air could not get through the coils. After you turn the a/c off, the ice melts and air is allowed back through the cooling coils. Check under your car when you are having this problem, then turn off the a/c. You should see a big puddle of water form under your car as the ice melts. If so, this could be your problem. I can't remember what the fix was, offhand. Try doing a search using "evaporator" or "ice"/"icing".

Good luck

Texas993

Thanks guys, all good suggestions. I am taking the car in on Monday, next week. Keep the suggestions coming.

I find it hard to believe the evap is freezing because it is usually so dry here. But it was humid yesterday.

I will search evaporator now.

Texas993

This is what I found on my search. Posted by Cecil:

"Mine would "freeze up" on highway drives during the hot moist summer. My mechanic moved the sensor from the top of the evaaporator down colser to the middle. It quit freezing up and now works fine. If your blows cold at first start and then quits blowing cold this could be the problem"

I will be bringing this along to my mechanic.

kkim

Yep, that's the one.

fbfisher

Could be your resister or it could be the a/c pressure switch. When ever the engine temp got to a certain temp the a/c would cut off.

Texas993

Ok, I will ask to have that checked to. The engine temps were low, but that does not matter if the resistor is bad. Thanks.

Kkim, thanks for your help.

I feel better armed with solutions before I go to the shop, rather than just a problem. $$$$$