Okay guys needs some help 03 F350 7.3PSD

a/c blows cool on max only but does not blow real hard on high.

Blower motor is loud like it is blowing but just not coming out of vents.

on reg a/c blows hot, actually blows hot on all other settings.

a/c compressor is on but blows hot through vents

Im thinking blend door and or something else.

Thing is I am not sure what or where to look and how do I check

 

The temperature issue sounds like a problem with the blend door. The system likely has a coolant shutoff that blocks coolant flow to the heater core in the MAX position.

If the air blows out of the proper vents on each setting, your poor airflow is likely caused by an externally plugged evaporator (dirt and debris).

Check to see if the air always blows from the defrost ducts. If so, this would indicate a vacuum issue.