Gutterslug

Noticed something about my truck the other day. I'm sitting at idle in the drive-thru to get my coffee, truck's in gear, and I can repeatedly hear this "click" come from under the hood and the idle drops a bit then it just pops back up again after about 10 seconds or so. It almost sounds like my A/C pump is kicking in/out about once every minute or so. It's not the grid relay (kept an eye on the voltmeter) and my A/C was off. I know my buddy's 91 Exploder did the same thing until I disconnected his A/C. I've had this truck for nearly two years now and have never noticed it before and now it seems to be getting worse and if I'm not mistaken my mileage is getting worse too but maybe that's just me halucinating. There's no rhyme or reason to it
Any guesses?

Alwaysworking

my causins alt. does that kicks on loads the engine and the kicks off. but if the engine senses its cold it uses the ac to load the engine to warm it up faster i think

powerrammaster

If the defroster was on , the A/C compressor runs to dry the air. (Doesn't matter whether you want the air cold or warm) You prolly hear the compressor kicking on every couple. Never heard of A/C used to put load on engine for fast warmup, our trucks aren't computer savvy enough to have that kind of action. The alternator runs continously, there is no clutch to engage/disengage.

local601

mine clicks as well, Spray some belt conditioner on it and see if it goes away. I changed my belt and it went away for about a month but came back. I never would have thought a belt could sound that way but it is a loud click and will go away for a short time if I spray it.

jc67

Yeah, mine's doing that too. But it seems to quit once it's warmed up. I'm trying to sell the truck right now so it's kind of embarassing not knowing what's causing it. Cause everybody can hear it, and I don't have a good answer for them. I think I'll try spraying it for now.

wannadiesel

It's the A/C compressor cycling.