I was talking to a friend who does A/C work and he suggested I install a valve (on/off) to by pass the heater core. Reason being- to make cabin area cooler in summer. He says he can install it in the engine compartment at the firewall where the coolant hoses enter. He explained that the factory installed dash mounted, slide valves are not as affective because the heatercore still gets water in it and when air blows across it, the cooled (a/c) air is slightly warmed. The idea is that you reach into the engine compartment and open the valve by hand when the Fall season arrives and close it when it's spring. It's just a "T" shaped, hand valve installed with clamps in the hose. Is there any reasons this wouldn't work or any drawbacks to doing it, besides having to remember to turn it twice a year (of course the next owner could just leave it open if they didn't want to mess with it)? What do you all think before I do it? Thanks.