My 2012 King Ranch F-150 with the Coyote engine the A/C at times will start with the defroster blowing hot air than about a 1/4 mile down the road the A/C will kicjk on and be blowing cold air out the dash vents. Sometimes when the truck is a cold start the A/C works immediately. Located in Florida and when the truck is sitting in the sun and is started it is always delayed before the A/C blows out the dash and is cold. Any ideas? Thinking it might be a vacuum pump going bad.

 

Ok what you need to do is get a second person, you look under the hood at the compressor coil while the second person starts the vehicle and turns the AC on and off and you check if the compressor coil activates when the AC is turned on. If I understand you correctly the AC does not blow cold air on start up air when the vehicle has been sitting in the sun and is hot, but it has no issue blowing cold air when the vehicle has been out the sun.
I do not know what vacuum pump you think might be bad.