First you should try adjust the air conditioning idle timing. If unsuccessful, then you can try installed a FICD. You can get it at chop shop which cost around RM30-RM50. It will stabilized the engine timing when the air conditioning compressor is on.

Viqq, you can ask the foreman to adjust the valve of the air con idle timing. Just said that the idle timing is too low when the air con compressor is on. Maybe you should ask several foremen to get second opinion.

FICD is a vacum valve that can stabilize the idle timing when the air con compressor is on. It will suck more air into the crankcase when the compressor is on, so the idle timing is stabilized. Just ask at the chop shop, I want a FICD that can stabilize the car idle timing when the air con compressor is on. But first, you can ask the foreman to adjust the valve of the air con idle timing for you. I hope this will help you. But sorry if I'm wrong.