Why trhe air conditioner is getting warmer after a few minutes the engine runs on 2003 Audi A6 Quattro

When i turn on the car the air conditioner runs automatically, then the air became warmer, and the engine fan stops working, and a smell like burned oil came from the engine, there is no visible oil leak, but its smell pretty intense for at least 30 seconds then stops

Asked by for the 2003 Audi A6 Quattro