Idle/Altitude Compensator (Non Comp. Controlled): Testing and Inspection
HAC Valve1. Disconnect air hoses from air cleaner and altitude compensator.
2. Disconnect vacuum hose from HAC valve.
3. Operate engine at idle and apply intake manifold vacuum to vacuum sensing port of the HAC valve.
4. Blow air through the HAC valve from the air hose and ensure air flows from valve. If no air flow, replace HAC valve.
Fig.46 - Checking Vacuum Delay Valve:
Vacuum Delay Valve
1. Remove vacuum delay valve.
2. Connect a suitable vacuum gauge to the vacuum delay valve as shown in Fig. 46.
3. Operate engine at idle and using a test hose apply intake manifold vacuum to other end of vacuum delay valve.
4. Note reading on vacuum gauge. Disconnect test hose from vacuum delay valve, while noting time required until reading decreases 11.81 inch. Hg, (300mm Hg) from noted reading. The time should be 7.5 seconds. If time is not within specified limit, replace vacuum delay valve. When installing VDV, face arrow stamped on VDV toward the HAC valve side.