2003 Honda Civic

My civic is experiencing an air conditioning problem, and potentially multiple problems. When I am idling, the air quickly turns warm. Giving it a little gas to get to about 1800-2000 RPM gets the air to start cooling again, even when at a stop, but this only lasts for about 10 seconds after I take my foot off the gas. When driving at full speed, the air is perfectly cold. Driving yesterday in 80 degree weather, I had the fan on the lowest speed and actually had to turn the temperature up two notches from the coldest setting because I was starting to get too cold.

The air temperature can be just as cold sitting still as it is moving at 60 MPH, but only if I give it gas.

The plot thickens, as some mornings when I first start the car, I can't get the compressor to engage at all, even at speed. Here's what happened to me Saturday:

7:30 AM - started, no cool air even at 70 MPH
7:45 AM - started again after quick stop, gave it gas, perfectly cold air. Stopped at a stop light. Air quickly turned warm.

My mechanic has had the car in the shop and is stuck as he can't figure out what might be causing the problem. Obviously, the first instinct is that it's a compressor problem, but the air is amazingly cold when it's actually working.

As it's just starting to get warm, I can't say for sure how long this issue has been around. I did have two hoses replaced by Honda 11 months ago because all of the freon had leaked out. My mechanic just checked the freon levels, which were only about.2 lbs below what they should have been. He went ahead and evacuated and recharged the system, but that did not solve any problems.

I am sure that the issue of not working at idle speed has been around for about 2 months. I took a road trip to Florida 2.5 months ago, and did not experience the issue, even in 85 degree weather while idling.

One thing my mechanic did notice was that the other day in the shop, the compressor clutch would engage and disengage while idling. I think I have noticed this before while driving at night as I've noticed my headlights repeatedly dim slightly and return to normal, without relation to the RPMs being produced.

So, I guess to sum it up the problems are:

1) no air when stopped, except with about 1800 RPM or higher
2) compressor sometimes will not engage first thing in the morning
3) clutch sometimes engages/disengages while idling

I'm happy to provide any more information that might help you diagnose the issue.