I have an 1976 K10 Scottsdale 4X4, The A/C has been retrofitted it blows Semi Cold when Idling , But if I give it gas while sitting still the blower speeds up and blows cold, Also when you drive it you can hear it start blowing harder and its gets cold..A/C has been charged , All Ducts been inspected and are good..Do I need a new Clutch fan or Blower Motor ? Maybe one out of an 1994 Truck?..Plus the A/C Blows Max regardless what setting you have it on...Its HOT in Oklahoma right now 118 today...Any Help or Advice would help ...Thanks !