I have a 98 Civic CX. On long distance drives, often the a/c stops blowing. I can feel cold air trickling out very lightly, and if I turn the fan all the way up, it makes a lot of fan noise, but no air is blowing in. If I turn it off for 10 minutes or so, the fan kicks in again, and it works fine. After three or four hours, it happens all over again.

Any ideas about the cause of this?

 

The evaporator coil inside the car is getting too cold. This coil works like a heater core in reverse, the fan blows air thru the fins on it and the air is cooled. Normally it condenses water out of the air and the water drips out under the car. When it gets too cold the water will turn to ice instead and cover the fins on the coil until it reaches the point where air can't flow thru it.

After you turn the A/C off for a while, the ice melts and airflow can resume. There is a sensor to automatically shut down the compressor before the evaporator gets too cold, appears it isn't working.