hi,

In the morning, when the engine is cold, i can't turn on the AC. After driving for at least 20 minutes, i can turn on the AC. and it works fine rest of the day.

otherwise, RPM drops and engine shuts especially while changing gear.

AC works fine when the engine is hot. it gets pretty cool also.

what could be the problem? is it engine tuning problem or something to do with the computer system?

i just want to know the problem before i take it to garage.

thanks.

What car are we talking about?

mitsubishi lancer . with 2000cc engine. around 10 years old car.

Possibly an idle air control valve.

Cleaning idle air control valve

WiKi - If the engine is operating a large number of accessories, particularly air conditioning, the idle speed must be raised to ensure that the engine generates enough power to run smoothly and operate the accessories. Most air conditioning-equipped engines have an automatic adjustment feature in the carburetor or fuel injection system that raises the idle when the air conditioning is running.