I've noticed a weird hiss that comes on when I turn the A/C on. It will hiss for about 5 seconds, and then go away. Then about 15 seconds later will come back and hiss for 5 seconds, etc. etc. I've also noticed it only starts to hiss once I'm driving. But it does not hiss when the vehicle is at idle or in park. I figured it needed a recharge, so I had the A/C recharged and it's blowing very cold air, but a very annoying hiss continues. Another thing I've noticed is that when I drive with my a/c on, it will mess with the shifting patterns of the truck. It did this with the old transmission, and the new transmission, it is odd. Do you guys have any idea where the hiss is coming from though? It just started doing this about a couple weeks ago. Thanks.

 

Sure its not the compressor turning on and off?

 

Hmm, I am not sure, what would you think it'd be doing that for if it was the condenser? Could the transmission shop have anything to do with that when they installed the transmission cooler, or? Today when I was driving with the a/c on, it pretty much hissed the entire time the a/c was on. It hisses for about 3 seconds, then it will stop for about 2 seconds, and then hiss for 3 seconds, etc. in that pattern. And it only hisses when the truck is moving. When the truck is in park, or when I'm at a stop light, the hissing will go away. Could it be a leak? The a/c remains to be effective though so I'm having some doubts about it being a leak. I wouldn't care so much about the hiss if it wasn't so often, but it pretty much consumes the cab the entire drive if the a/c is on, and little stuff like that drives me nuts[8D] Wh