Any one can help i got a civic 1994 GLI model once the car is on for first 15 min the aircon work fine.. but after i drive around in slow speed in the traffic light the air con will stop wroking no cold air come out and when is idle the rev is going up and down between 1500rpm to 1000 rpm it seems try to get the compressor working, if i drive in a bit high speed like on the highway it seems the aircon work fine and have cold air come out, if any one have any sugesstion it will be really helpful thanks a lot guyes

 

From your description it sounds like the condenser fan stops working. The condenser is up front next to the radiator, and it rejects heat from the air conditioner. Without the fan, the condenser overheats which causes excessive pressure, then the compressor cycles on and off on the safety switch. When you are driving that forces air thru the condenser and it works OK again.

So wait until it is not cooling, then open the hood (engine still idling) and see if the condenser fan is running. If it is then there may be another problem, like the compressor clutch not engaging when it is hot.

 

Yep, I had the same problem. It was a bad fan motor.