My A/C is not working very well, sometimes it blows very cold air and others times its just air. I can be driving down the highway at 70 mph and it will change from cold to just air and it feels clammy. R.P.M.s do not seem to be a factor but acceleration does. For example if I were going over a mountain on the way up it would be blowing cold air on the way down just air. I can idle and get cold air then it changes. I now have 36,850 miles of course! Any ideas would be appreciated.

Thanks Welder

 

welder, If you call you dealer and tell them you just passed 36000 by a couple miles or your will be over 36k (witch ever you prefer) they more than likely will help you either way. They want you to buy another truck from them in t5he future so its worth a shot. A/C parts can be pricey$$$ It probably did this before you turned 36 but didnt notice it because it wasnt hot out. Does it do the same on recirculate? (turned all the way to the left.)

 

Yes it does do it on recirculate

 

There have been several recent threads that sound similar to yours. Their A/C was freezing up....most likely due to low freon. Once the ice melted their A/C started blowing cold again until the process repeats.

I'd skip the dealer and have your freon charge checked.

 

Yep... I have an 03' and it did the same thing just a month ago. Luckily, I only had 31000 miles and they did not give me any trouble at all at the dealer. Turned out it was low on freon. My question to the dealer was my truck is only 2 yrs old, where did the freon go??? They said they checked the system for leaks and could not find anything wrong. I cannot imagine where freon can disappear to in a 2 yr old truck... I told them that I was going to bring it back in a cuople months and have them check it again before my warranty is up just to see if any more has dissappeared. I bet they won't give you a problem if you are just over 3k or 4k miles though. Wish ya luck...

 

Seems like low Freon to me too from the symptoms you are describing. Freezing up is a possibility but that usually happens only in very high humidity environments and if there is a condesed water drain problem. Going up the mountain the ambient temperature will drop enough to make marginally working AC to work good again as the temperature difference between the outside and inside is smaller. I'm pretty sure your truck is using refrigerant 134a and that stuff will leak out faster than the old fashioned R12. Supposedly this is contributed to different solubility and permeation rates of 134a in and through the seal o-rings.