Ported Vacuum Valves

Fig. 22 Ported vacuum switches & vacuum control valves:

1. With engine cold, ensure that passage A to B is closed, and passage A to C is open, Fig. 22.
2. Start engine and run until it reaches normal operating temperature, then ensure that passage A to B is open and passage A to C is closed. On 4-port valve, check A1 to B1 and A2 to B2 separately.
3. If valve does not operate as described, replace valve.