I was towing a 10 ft enclosed trailer witha piano and other misc stuff in it on saturday from tacoma, wa to spokane wa (about 300 miles). i held off using the a/c for as long as i could but started to use it a little on flat parts of the road and down hill.

it started to randomly switch from floor to defrost and to vent on its own and then the cold air would stop. id turn everything off and turn it back on for it to work for a few minutes the go wacky again. on the way home i was about 800-900 lbs lighter and it was almost 90 degrees out so i tried the a/c again and it worked for a few minutes then completely stopped blowing cold for the rest of trip, even after a few engine shutoffs and even to today there is no cold air. I can still here the compressor kick in but no cold.

ive talked to a couple mechanics and they said it could be the doors that open to let the cold air in and also to doors that control where the air goes that could be messed up. could it be that? and how do i check/ fix

my question is did towing do this or was it bound to happen because the temp gauge was staying pretty warm when ever i was on a slight uphill grade. for most of the hottest part of the day it stayed at roughly 220 or so and up to im guessing 230-240 on the steep grades. is that normal for towing in heat or should i look at my cooling system. dont know when the coolant was last flushed and ive had it for over a year but have only put 5k miles on it.

also only got aboot 9-10 mpg for the whole 600+ trip seemed bad for only towing maybe 2000lbs and only 1000 on return trip
fyi its a 00 qc 4x4 with the 3.55 gears with factory tow package with 142k on it.

sorry it was long but had to explain everything

ps couldnt believe the difference when the sun went down and temp dropped, climbing snoqualmie pass was a breeze.

 

ever check how charged your system is? do that...be my bewst guess that its low on 134

 

that wouldnt explain the random switching of modes and it was blowing ice cold b4 hand