before i get the obvious responses, i did several searches on this already.

I first noticed it a couple weeks ago, and it only seems to happen when it's cold out (arizona cold about 40-50 degrees). What happens is when i'm sitting at a light or in a drive through, i'll hear a loud "click" from the engine bay, feel the car shudder a bit and then the RPMs go from about 700 to about 1200. then in about 10 seconds or so the RPMs will lower back to normal idle. then it happens again a couple minutes later. It's the same sound as the A/C being turned on but i have all my fans off. is this a common thing in cooler weather? or is there a relay problem or soemthing? thanks!

 

my car does the same thing and most other cars that I have seen. from what I've been told its the thermostat for the engine coolant clicking on and off, it does it quite frequently when cold to help warm up the coolant.

-Justin

 

ah, i see, thanks man.