I have a 2004 Mitsubishi Lancer... Same problem. When the temperature was >99 degrees, it would feel like a blow dryer on high. Took it to Midas and they found a leak in the compressor (1500 repair!???) Took it to get a second opinion and found the valves on the high/low system were leaking. Only cost me $30 and it works like a champ now.