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.
Dominating, But Troubled, Boxing Champ. Sports. Mike Tyson had a controversial career, but a very successful one -- at least in his prime. He also became the lineal heavyweight champ when he knocked out Michael Spinks in 91 seconds of the first round in a 1988 bout.