99 CLK430 A/C Problem
 

I have a 1999 CLK430 that is having intermittent problems. On four seperate ocassions the A/C would cool for about 2 minutes after the car was started then it would stop cooling. The blower motor would continue to operate but just blow warm air. The next time I drove the car the A/C worked just fine. On all the occurances the car was sitting in the sun and it was above 85 degees. It appears to be an electrical problem. Does anyone have any ideas what is causing this?

Thanks