Cooling System: Heater Control Valve

 

A heater control valve may be located in one of the heater hoses to regulate coolant flow to the heater core. The valve is usually vacuum-controlled, which is operated by controls on the dash.     

 

 

The valve is used help control heater output. 

  

 

Insufficient heat, or heat that can’t be turned off may indicate a problem with the heater control valve. Inspect the valve to make sure that its vacuum line is properly connected. If the valve has an external linkage arm, operate the heater controls and watch to see if the valve changes position. If you have any doubts about the valves operation, have the heating system checked by a qualified service professional.