By replacing it with a new set, if one breaks you change all at the same time.
where is the heater control valve for a 1997 ford expedition
NO
The idle control valve on a1999 Ford Expedition is on the upper part of the engine by the throttle body and fuel injection.
iac valve...idle air control valve
It's on the passenger side of the motor under the valve cover.
its on the throttle body
its in the oil filter housing
wheres the bottom ac valve on a 1999 ford expidition
.cv valves are located on top of your engines valve cover.
They are under the coils in the valve covers.
Do you mean PCV ? - ( Positive Crankcase Ventilation ) valve
In a 2003 Ford Expedition : The ( 2 valve per engine cylinder version ) if that is what you are asking