Heater shutoffs, eh? Mine are near the firewall in the heater lines coming from the
engine. Pretty simple I would guess, but I did not install them. Mine are merely valves
like on the radiator but connected inline to the heater hoses. One for each line. No, it does not make the interior any cooler. You are merely isolating the heater core from the engine. So you are not circulating coolant thru the heater core. Remember you still have the tubes running directly under the shifter area going to the front radiator. This gets you plenty of warm air. I don't think installing them should be difficult.
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