hot air coming through defroster on top of the dash after replacing actuator

Which actuator did you replace? These GM trucks have been known to have incredibly annoying HVAC issues. I think there is a recalibration you have to go through when you replace it.

one on the passenger side. I may have missed the recalibration part. Can anyone tell me how its done?

pull HVAC fuse inside truck for sixty seconds with key on then reinstall it will reset actuators.