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Discussion Starter · #1 ·
After doing without A/C for a couple of years, I finally fixed the leak and charged the system. The a/c has been cooling the truck nicely and a thermometer in the vents shows 42 degrees after about 5 minutes.

I made the first trip of more than a mile on Thursday. The A/C worked fine however, the wife noticed a loud ticking noise coming from the engine. You can not hear it inside the cabin even with the windows down. Only when standing outside can it be heard and it is a sound that I've never heard before.

It sounds like its coming from the front of the engine, not the a/c compressor. More like the area of the cam gear or the number 1 cylinder under the valve cover. The ticking gets faster, but not louder as the engine is revved. It only makes the sound when the A/C is turned on. Turn it off and the sound goes away. Also, it only makes the noise after the truck has been driven a few miles with the a/c turned on. Drive the same distance with it turned off and there is no abnormal ticking at all.

First I thought it needed a valve adjustment, but when I realized that the noise went away if the a/c was turned off, I thought it had to be something else.

Anybody have any ideas on what to look for? This one has me stumped and I am not in a position to toss parts at it in hopes of finding the solution.
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