no heat in van blowing cold air out vents

the ford dealer replaced a yh-1752 part then when it was still blowing hot air said it was the actuator cosing me another $600 my question is why didnt they replace the actuator in the first place instead of charging me $1100

Either both parts were in failure or they didn't know the issue for sure and threw a couple parts at the common causes till the issue was resolved......at least I pointed you in the proper direction though. Sorry about the cost but, dealers are more expensive than any other shops usually.