Civic idle problems with air conditioning only

[shamirm]

Hello, i have a 1997 civic ex that i just bought. The car runs great and gets great gas mileage. The car does have a problem though, when i stop and the a/s is on the car idles very roughly and drops down somewhere near 500 or 600, when it is usually at 1000 RPM. I was wondering what a problem could be, if i adjust the idle, would this fix the problem?

[WMX267]

I have the same problem with my 2000 Civic Vti. Whenever the A/C is turned on and I release the throttle (either from revving or shifting to neutral), the engine drops way below idle. This doesn't happen when the A/C isn't turned on. It catches the engine right on idle. Sometimes it even drops so low that the compressor of the A/C clicks again.

The interesting thing about it is that the problem is most definite to occur whenever the car has been parked under the sun or during hot weather. It doesn't usually occur during cooler days - never during the evening.

I tried to adjust the idle so that when it drops, it does not come to the point where the A/C compressor engages again. The problem is, when the A/C isn't on, the idling is too high (about 1000 - 1100 rpm). Not exactly economical. Plus, when you shift to neutral and let your car "free wheel"[?], the idling goes up until you slow down. I'm not really sure if this is connected to the "A/C IDLE PROBLEM".

I tried testing the IAC Valve but it works just fine. I tried cleaning it (blowing the carbon out). It helped a bit, but didn't actually solve the problem. I'm thinking that it could be connected to a PCV Valve problem or a dirty throttle body. I dunno.

Actually I have a hypothesis about this problem. 1) Too high freon pressure level in the A/C system; 2) a clogged Expansion Valve 3) or some other problem with the other parts of the A/C system .

Someone help us!!!