quote:My factory heater valve works perfect.
This is open to debate. Standard Pantera think is the stock valve and cable control were not designed together. Thus, the throw of the lever does not give complete throw of the valve. You can adjust the valve functioning parameters (at the cable clamp on the heater valve) two ways --- so the dash lever closes it completely but won't fully open it, or the other way around. Fully closed option will limit heat in winter, as it won't fully open the valve. Fully open option (to maximize winter heat) means it doesn't fully close, and in summer your AC is having to deal with air being heated as it travels through the heater coil that is being fed by the trickle of fluid getting past the almost-but-not-quite closed heater valve. Shut off valves in the engine compartment can serve as a complete shut off, allowing you to adjust the cable clamp at the heater valve for full open in the winter, when you will of course open the engine compartment valves.
Larry