Weird AC issue....

Good morning, chronic lurker, just need some opinions on this one. 15 Z71 Tahoe, 130k miles. On long trip, 3 hrs in, ac on auto, 73F, air through front vents slowly stops blowing until you notice temp is going up. You can crank the fan speed up and it sounds like a tornado on passenger side floor board but no flow. Turn off AC and just pull air from outside and blows fine. Really weird, will continue to do this for the remainder of the trip. Initially I thought it was a bad blend door, but not the case as I can get it to blow, just have to mess with it. There is a ton of condensate coming from the front passenger side and rear from the AC. I think the evaporator coils are freezing up, but not sure why. In away from the house on a trip and just wanted to see if anybody else had similar issue and if it was worth dealing with away from home or just hold up until I can get back. Read some posts about similar issue pre 2015 and they had to reset the climate control system, or reflash.

When you crank the fan off does it come out of auto? Like you I’ve seen a few posts about this. I don’t think it’s anything that should effect your trip back other than inconvenience.

condensation is normal and will be more or less depending on the outside environment/temp/humidity level, without a tech tool it's really hard to say what could be going on unless you can tell for sure if the actuator is getting stuck or not, you could do that by moving all the controls back a forth several times and see if it is working properly or not, if you really feel it is the ac causing the issue then you can pull the fuse and take it for a drive and see if you still get the same results or not.

Sounds like you are low on freon which can cause the evaporator to ice up and affect AC performance. There was a TSB on some of the 2015s where the factory put in the wrong amount of freon. Had the TSB performed on mine and a new factory sticker under the hood showing the correct amount. Good luck.

Appreciate it guys, I'm gonna put some gauges on it and see where it's at if I can find some, try to get a scan tool when I get back home. It's just acts really weird, does seam as if it doesnt want to blow through the front at times, but sounds ok in the back. Appreciate the advice, I'll update if I figure anything out.

Just an update, didnt have a good set of gauges to put on it, but bought a bottle of the quick fill freon with the cheap gauge. Let the AC run full blast, compressor engaged, showed the level as being in the green. Messed with it on the way home, took it off auto and just had the blower on low, ac on. It eventually stopped blowing through the front vents. I shut the ac off and kept the blower on, it eventually started to blow back through the front vents, warm at first then cold, then back to warm, as soon as it started blowing warm i turned the ac back on and it was cold. 30 min later same thing, stopped blowing through the front. This time I cranked the blower on high and it started back through the vents again blowing cold, never shut the ac off. Weirdest thing, driving me crazy.

Another update: called my mechanic, tsb out for weird hvac issues, calls for a reprogram.
TSB # PIT5383 C

If you like and are going to keep this truck a while Z, get a bi-directional scan tool so you can properly, quickly diagnose and fix it. Yours does not use the old Tech-2 but rather the new MDI with GDS software. VXDIAG Nano works with laptop or tablet and GDS software.