A heater control valve is simply a water valve which allows more or less water to circulate through the heater core, depending on how much the valve is opened.he coolant flows  through the heater core all the time.    Temperature is controlled by:    Temperature blend door-control how much air travels through  the heater core -   A small motor that controls the blend door-a rather common  failure point.
In 2002, Tyson fought for the world heavyweight title at the age of 35, losing by knockout to Lennox Lewis. Tyson retired from professional boxing in 2006, after being knocked out in consecutive matches against Danny Williams and Kevin McBride.
The heavyweight division has been an afterthought in America since 2002, when Lennox Lewis gave Mike Tyson an eight-round beating in Memphis. Lewis held the crown for about another year before retiring, and since then the Klitschko brothers, Vitali and Wladimir, have gotten rich by defending their belts in Europe.