Wasn't sure how else to title this but I'd like your opinions on something. I just took a trip last week from Pittsburgh to Williamsburg, VA (close to a 7 hour trip). On my way down there it was a very hot day and for the 1st half of the trip everything was fine. Truck was running well, ac working well, etc. Well, when I hit I95 the trouble started. For whatever reason, I was running into traffic jam after traffic jam for no reason on that highway! Well, after about the 5th jam, my AC started blowing hot air. I checked both sides (low side and high side) with my gauges and they read normal. Well, eventually after the truck sat for a little bit, the cold air returned. The rest of the trip down it was fine and it's been fine ever since. I didn't run into anymore traffic jams after that thankfully. It was about 95 that day with the sun beating down. Anyway, I know my system is old and is going to need replaced soon. Could that have just been an old compressor acting up in the extreme heat and conditions? Did it maybe just shut itself off due to the conditions and how old it is? Or, is there something else that could've caused that? Engine never overheated or even got excessively hot through all of that. AC just blew hot air right after the stress of the heat and traffic jams. Thanks for any advice on this.

 

Its happened to me before.. about a week and a half ago - not quite sure what caused it.. I was driving around on I14.. a pretty hilly area out here - and all of a sudden for about 10 seconds it blew hot air out at me, and suddenly kicked back into cold air.. fairly odd :-S

 

Only time I had issues with traffic and hot ac. My efan was not working.

Leads me to think you have a flaky fan clutch.

 

it sounds like the clutch in the a/c compressor is slipping. when it works for a long enough time especially on an older truck, the clutch heats up and can start to slip. look on the front of the compressor and see if any of the bolts on the front are turning black or look for color change from heat. this is a very common problem on a/c systems on transports

 

Same thing happened to me....I sat idling for a good 45 mins trying to cross the border back into the US from mexico. I noticed it only blew hot air once the temp got to 220 on my scanguage. The needle looked like it hadnt moved, but the SC read 220 when the AC would blow hot air. As soon as I would rev the engine up to 2-3K, the temp would come down and the AC would work fine until it would hit 220 again.

 

Fan clutch or loose belts, the condenser needs air flow to transfer heat. no flow, no cooling.

 

I'm no A/C expert but I hover around our A/C mechanic at work and try to pick up on a few things. I'm wondering if the pressure got too high and shut the system down. When it gets hotter out it can cause pressure issues. I'm assuming unless you got the gauges on it immediately they would of returned to normal. I also know on my dads older chevy truck its started to get a bad connection on the A/C compressor. Every now and then the compressor won't come on and you get out and jiggle the plug on the compressor and it kicks back in.