Re: AC blows hot & humid after restart ('04 6.0L)
When you shut the truck off, you have a huge chunk of iron that's well over 200 degrees sitting under an insulated hood.
After sitting a few minutes, it will heat up the entire heater/AC system.... even the firewall and the cab ducting. After you start the truck, it has to cool down all that material. Plus, the heat soak will raise the refrigerant pressure in the A/C sytem, and it will have to cool down some by running outside air and drop the pressure before the compressor will kick in. That's the warm, humid air you're getting. Once the compressor kicks in, it will cool almost instantly.
If it's a major nuisance, and you know that you're only going to leave it for a couple minutes, get a second key made so you can leave it running and lock it. If you're going to be gone for more than a couple minutes, as you said, it's not the end of the world.