Weird idle problem

[crossman]

On my '91, when I start it up and let it idle, I can hear a click noise under the hood and then the RPM's will jump about 50 RPM, then immediately go back down. Then another click, etc. It will do this whether the motor is warm or cold. I openned up the hood and found that the click noise is coming from the power distribution box. What could be causing this to happen?

 

[mrboyle]

Was the defroster on?
If so, the noise was the A/C compressor cycling. When the defroster is on the A/C is cycled to prevent the heater from over heating the windshield and causing it to crack.

 

[crossman]

Hmm... ya know I think it was. I never even thought about that. I'll have to check it out tomorrow and see if that is it. Thanks