I am getting an electrical sounding tick/click coming from what seems to be under the dash, just to the left of the steering wheel, if you are facing it. *That is where I think it is coming from* Anyways, it happens every 10-15 seconds, only when the truck is in gear, driving down the road. It does not happen when parked at a stop light in neutral. I am mystified as to what it is. Nothing is wrong with the truck as far as performance, there is just a really annoying tick that keeps happening. Anyone know what it is?

 

The A/C compressor clutch in R134A systems like yours engages about every 10~20 seconds while driving. The click gets louder with age and some of them even chirp. Try turning the selector to OFF, FLOOR ONLY or VENT ONLY to turn the compressor off - see if that makes it go away.

 

Thanks Bob I will try that, I never thought about the A/C, but it makes sense.