If you are asking about the thermostat, you can drop it in boiling water to see if it opens. If you suspect it may be bad just replace it with a new one, they are cheap enough.
heater Control valve for 2002 Lincoln Ls
About halfway down the side of the radiator on the passenger side.
valve cover gaskets valve cover gaskets
A 2000 Lincoln LS has a control valve located inside the engine compartment, on the passenger side. There are five hoses that connect to the heater control valve which also has two cylinders that rest on top of it.
The heater control valve is bad. Sometimes the dual heater control valve will go and the AC will blow full heat.
How to fix heater in Buick there is cool air ,fan is work .but no warm air
the heater control valve or DCCV (dual climate control valve) is located next to the radiator on the passanger side just below the high pressure side service connector
Its in between the valves
Replace your IAC Valve-No more stalling
do you mean the thermostat
On the pump
The (DCCV) dual climate control valve may be damaged also called heater control valve.