I had a recent issue come up with my A/C. I have an '03 Cooper R50 with automatic climate control. This happened when we had a hotter-than-normal spell of weather in the desert. When I started the car in the morning to drive to work, the A/C worked fine. When I left in the afternoon and the temperature was at 115-117, the A/C blew scalding hot air (probably hotter than the outside air) until I was about halfway home, then it started to cool off. I had driven probably 15 minutes before the A/C started cooling at all. Any idea what might be causing this?

 

If i had to bet $$, start with a recharge...
R134a works about as good as the old freon at regular temps and preasures, but at very high preasures...such as those common with a low charge/and or a very hot day (accidently simulated by many accidently who drive gen1 cars with a low speed fan not working), the r134a is not as effective....similar results happen when a system has too much oil.
My suggestion....try it out on a cool(er) day/night....see if it works...
With the auto, the dampers that open and shut the doors to blend hot/cold could be stuck, but low refergiant in a 10+ year old car is more common....

 

Thanks for the response. I was thinking along those lines, but the solution isn't always simple. I had the system recharged about a year ago, but it may need to be topped off. It's worth a try.

 

Many people I know are not aware of how the AC works in 'recirculate' mode. If you do, then forgive me.
In recirculate, the air for the AC is drawn from the inside of the car, thus is actually much hotter than the outside air. Takes longer to cool off the interior.

...ED

 

That depends on the temp of the outside air. For those in 115+, odds are the interior air will be cooler than that (after a minute or two...)

 

This happened on two consecutive days. Fine in the morning, scalding hot in the afternoon. The air coming out of the vents was hotter than what was in the car (I had the driver window down to cool down the interior air a bit first).

 

Sounds to me also that it's a freon level issue, if it' slightly too low or slightly too high it will act up more in extreme conditions.

Mine likes to be about 2/3 in the good range with my cheepo refill kit.