3/8 inch, copper
faulty control valve on heater or air in the lines
Begin by removing the water supply lines from your Nissan heater core. Remove the heater core retaining bolts. The heater core will come out.
how to remove the lines from the heater core on a 2001 expedition
Disconnect the send and return lines from the heater core and use a hose coupling and hose clamps to connect these two lines together
Yes the lines can leak when they rust through.
To remove heater core AC lines, first, ensure the engine is cool and disconnect the negative battery cable. Drain the coolant from the cooling system and use an appropriate tool to disconnect the AC lines from the heater core. Be cautious of any residual refrigerant and wear safety goggles. Finally, remove any retaining clips or bolts securing the lines and pull them away gently from the heater core.
most likely your heater controls run via vacuum lines. cracked or broken lines could cause this.
You will need to remove the water lines from your heater core. Remove the heater core retaining bolts. Reverse the process to install the new heater core.
Tie the 2 water lines that run to heater core together
The heater/ac doors are all electric. They are not vacuum controlled.
The major material used in the construction of transmission lines is aluminum alloy. Steel is also used to reinforce the lines. No insulation is used for overhead transmission lines.
Diagram for vacum line / heater lines for 1983 nissan 280z