A/C issue

I have a 2017 Tundra with 151,000 miles on her. I purchased the truck new on 12/08/2017. My air conditioner blows cold air until the truck warms up and then no longer blows cold but warm air. All my service since the truck was new has been performed by the dealership from which I made the purchase. Due to dealership costs, I had another shop take a look at it this morning. I am told everything checks out ok and they suspect it to be an electrical problem somewhere in the system. He drove the truck a mile or so with cold air flowing and all of a sudden it turned warm. Has anyone else had an issue like this? I also noticed that when the air turns off and blows warm, the amount of air blowing through the vents is reduced by about one-half.

 

have them check the pressure. Might just be low on refrigerant which can cause the evaporator to freeze up.

After the AC gets "warm", turn off the AC but leave the fan running for 10 minutes or so, then turn the ac back on and see if it's cold again. If so, it's probably the evaporator freezing up.

 

Thanks. I've done that with no change. The ambient temperature today is in the upper 90's today. The truck has been sitting this afternoon and it will not blow an ounce of cold air in these temps. I can start the truck in the morning and I can expect to feel cold air for a little bit. It will eventually change to warm (ambient) temperature. I drive the truck 3 miles to drink coffee with friends and enjoy cold air in the morning. After an hour or so, I drive back home and by the time I get home, it begins to blow warm air.