I've read several of you have been unimpressed with the cooling qualities of some of your late model trucks. My fix that will blow ice cubes at you is a simple heater core shutoff valve that was standard on many vehicles up until the last 6 - 8 years ... the big 3 had to cut cost somwhere I guess. On most newer models, the heater core is circulating hot water from the moment you start up. On hot days your A/C has to not only cool the outside temp, but also cool the air flowing through the heater core. I selected a manual valve off a 70's Mustang, but vacuum operated ones can be installed if you have a known vacuum source when the A/C is turned on. Just splice it in the heater hose coming off the water pump. I'm not going to install a control cable, but simply open it up this fall when I need the heater working. My defrost works adequately this time of year without opening the valve.
