Reply to "heater shut off valve"

They allow the A/C to cool the car without first having to overcome the hot water trickling thru the heater core, which is fastened directly in front of the A/C evaporator. It also prevents you being killed or severely injured when (not IF) the 2 short heater hoses under the dash rupture at high engine speeds and fog the windshield opaque while scalding your foot. Installation is idiot-proof if you can select a pair of 1/4-turn brass valves at your local hardware store, and the right size pipe nipples to push in the heater hoses. Alternatively, order a complete kit from the usual Pantera parts suppliers. Cut the hoses in a place that will allow you to reach the on/off levers for the new valves. Some guys put them down near the rt rocker panel and simply reach underneath to turn them on/off, or place them up near the surge tank cap, opening the decklid to turn off/on. This of course means adding some extra length of heater hoses and clamping the valves down so the extra hoses don't flop against headers or something else damaging.