So the woman and I took a short trip to Utah today. Well on the way home, AC was on the second setting, ice cold. Aimed at my face. All of a sudden I notice it isn't blasting in my face anymore, but I can still hear it. It somehow started coming out on the defrost vent on the dash. No setting changed that. Then all of a sudden it diverted half of it back to the vents. Then about 5 min later, all on its own, went back to normal and all the settings working as they should.
Anyone seen this?

 

I would first start by looking for a vacuum leak. The defrost setting is the default setting for the HVAC system. And whenever there is a vacuum leak it goes to the defroster vents. When it went to the defroster setting did you have a huge load on the engine as that would indicate a small vacuum leak.

 

I was going uphill in the heat. I know the truck didn't like that lol

 

LOL. Yeah I'm pretty positive you just have a small vacuum leak lol. The shop truck at work (99 F-150) don't like it when I step on the gas, takes the a/c away from my face lol.

 

my truck kinda did the same thing, i turned the air on, setting on feet and head, and it was only blowing on my feet. and i switched it around to feet and other settings and it finally started coming out both locations.. so i would think its sorta like what you experienced. not sure

 

What is a good way to hunt for a vacuum leak?