98 Altima GXE

My idle keeps dropping when the ac compressor comes on. I checked the IAC. Specifically, I checked the FICD (fast idle control device). It is wired into the compressor clutch and opens when the ac is engaged. It is functional. The only thing I can think of is a mechanical issue with the compressor causing a heavy load at start up.

My RPM's are at 750 at idle. When the ac kicks on it drops to 500 and then goes back to normal idle range. The FCID is supposed to eliminate this dip. Do you notice the same thing on your Altima (98-01). Do you have any suggestions?

I don't want to replace the compressor unless I'm certain that is the cause. I checked the pressures and everything is fine. It blows cold.

I doubt it's the compressor causing this problem.

How many miles are on your car? Carbon buildup inside the intake or throttle body, or IAC, etc can cause this issue. So can dry rotted/broken vacuum lines.