For 1990-2009 cars

### Vacuum Logic Table

Vacuum is supplied to the control head through one input port and sourced to 4 output ports. The ports are referred to according to their corresponding functions within the HVAC module.

These ports in turn interface with a 6 port/6 conductor vacuum harness. It connects the control head to the vacuum source and the HVAC module. The vacuum is switched according to the following logic table.

HEATER-A/C CONTROL | PORT 1 (YEL) | PORT 2 (RED) | PORT 3 (BRN) | PORT 5 (BLU) | PORT 6 (PPL)
--- | --- | --- | --- | --- | ---
MODE | DEFROST | HEAT | HEAT/DEFROST | A/C | SOURCE
BI-LEVEL | VENT | VAC | VENT | VENT | VAC
VENT | VENT | VAC | VENT | VAC | VAC
HEAT | VENT | VAC | VAC | VENT | VAC
BLEND (DEFOG) | VENT | VENT | VAC | VENT | VAC
DEFROST | VAC | VENT | VAC | VENT | VAC