High Altitude Compensation System (HAC)

High Altitude Compensation System:

PURPOSE
Leans A/F ratio when the vehicle is driven at high altitudes.

Engine Compartment Electrical Components:

LOCATION
Solenoid is on firewall. Internal passages within carburetor.

OPERATION
The control unit calculates the altitude from the signal sent via the vacuum/pressure sensor. When the vehicle is driven in high altitude, the control unit energizes a control solenoid. The control solenoid then opens a passage, allowing air into the main air bleed of the carburetor, therby leaning out the mixture.