I've noticed a loud clicking noise, like a solenoid coming on and turning off; it idles up on the click and then idles down when click noise sounds again. Almost sounds like when A/C comes on, but no A/C at 40 degrees. Could it be the IAC - it's only five months old.

Thanks!

 

I do beleive if you are using your defrost the AC will kick on and off to remove the moisture from the cab.

 

Thanks, I'll turn off the defrost and see if this does the trick.

 

the A/C will also run on floor/panel and floor/ defrost

so make sure you try it on only panel vents

 

The AC will cycle the compressor even at low temps even if the system is not physically turned on. It's designed to do this to lubricate seals and circulate refridgerant. The system is governed by an ambiant temp switch which completely disables the AC only during extreme low outside temps. The clicking is your AC compressor clutch engaging normally and the engine control module (ECM) aka computer, revs up the engine to compensate for the added load required to run the system. I'm not AC certified but I have been trained and I read alot. I hope this helps.

Chevyssuck

 

The A/C unit was the loud clicking noise - thanks guys for all you help! I never realized that the unit worked even in the winter months.

 

If you have a faulty A/C compressor, it will case the rpms to spike over 1000. Glad this wasn't your problem.