Editing Z31/hotairfromac php (section)

==== Hot Air From A/C Vents ====

Commonly, air flow or temperature control issues are vacuum-related without a single universal cause or fix.

* Any leak in the vacuum system can cause not only heating and air conditioning issues, but also engine performance problems.
* Check the two vacuum lines at the firewall on the passenger side for cracks and leaks. One line goes through the firewall to supply vacuum to the climate control solenoid array, while the other controls the water cock.

There are also three vacuum lines that run back along the fender well to the
[https://dev.z31library.com/xenonzcar_archive/z31/images/AC%20repair/vacuumcanister.jpg vacuum canister]. Inspect all of these lines for cracks and leaks. Replace any that feel hard or brittle.
Most lines are color coded: at the canister there is a blue, a white, and a red striped line.
Once identified, run new lines and remove the old ones.

* White: Connects the manifold vacuum source to port M on the vacuum tank (should have a built-in one-way valve).
* Blue: Runs between the water cock and the magnet valve on the vacuum tank.
* Red: Goes between the interior door controls and a live feed from the tank, sometimes labeled as "F".