Mercury Repair Questions? Ask a Mechanic for Answers ASAP
Removal and Installation
I am sorry if that did not open I will resend another.
The vac line on the heater control valve located in the heater hose runs to the control head in the dash.
Maybe I can help you with your situation.
The gray line goes to the heater control valve vacuum switch.
Here is the vacuum schematic
It feeds the heater control valve
The heater control valve is actuated by the heater control valve vacuum switch (manual climate control) or the heater control valve vacuum control circuit (Electronic Automatic Temperature Control (EATC)). When the heater control valve is closed (full vacuum), coolant flow through the heater core is shut OFF and A/C cooling efficiency is increased.
Here is the lines coming from inside the car
Then they go to these connectors
The vacuum reservoir is located under the dash next to the blower motor on this vehicle.So the black supply line comes from intake manifold vacuum to the reservoir then to the control head and the heater control vacuum switch then back out to the heater control valve in the heater core hose.