High Altitude COMPENSATOR (HAC): California
- Disconnect White-striped vacuum hose from HAC. Connect vacuum pump to HAC and apply vacuum. At low altitude, 3900 ft. (1200 m) or less, vacuum should leak. At high altitude, vacuum should hold.
- On low altitude vehicles, disconnect Black hose from HAC and connect vacuum pump. Vacuum should hold when applied. On high altitude vehicles, disconnect Black hose from HAC and connect another vacuum pump. Hold vacuum with first pump, and apply vacuum with second pump. Vacuum should leak when applied.