[Thealien]

I struggled with the same decision for a long time. I am doing a no expense spared build on a 1972 blazer, 2 Wheel Drive. I would really have liked to clean up the firewall. I decided to stay with the original heater and evaporator box. I am using a new Sanden compressor and new condenser.

There are a couple of things that swayed my decision. All of the replacement AC systems do not use outside air and block off the passenger fresh air vent. Some have said this affects the defrost function some. The other thing that helped me decide to stay with the original evaporator box was the size of the evaporator. The factory evaporator is almost the size of the entire unit that goes under the dash with the replacement units. This might not be as much of a concern in a standard cab pick up truck or a car. The interior of a blazer is much bigger and more difficult to heat and cool.