Altitude Compensator: Description and Operation

Fig. 32 High altitude compensator (HAC):

To meet the Federal requirements at all altitudes all feedback carburetor vehicles are equipped with a high altitude compensation system, Fig. 32 in addition to the feedback carburetor system. The high altitude compensation system consists of a high altitude compensator (HAC) and passages for additional bleed air.

The fuel/air ratio is maintained at high altitude by the HAC to approximately the same ratio as sea level by supplying additional bleed air into the primary main well through a valve controlled by an aneroid bellows of the HAC. Fuel/air radios are controlled precisely by the feedback carburetor with high altitude compensation to comply with the applicable emissions standards at all altitudes.