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.
At age 20, Mike Tyson became the youngest heavyweight boxing champion of the world. Learn more at Biography.com. Mike Tyson is a former heavyweight boxing champion who's served jail time and appeared in several films. Who Is Mike Tyson? Born in Brooklyn, New York, on June 30, 1966, Mike Tyson became the youngest heavyweight boxing champion of the world in 1986, at age 20. He lost the title in 1990 and later served three years in prison over rape charges. He subsequently earned further notoriety by biting Evander Holyfield's ear during a rematch in 1997.