Vacuum Transfer Switch

This three-port vacuum transfer switch and spring-loaded vacuum actuator combine to give Outside/Recirc air door three positions: Off or 0% outside air; 20% outside air; and 100% outside air. With engine running, push system "OFF" button and check the following:

1. Outside air door is on 0% outside air, switch plunger is retracted and touching lever.
2. Push "LO-AUTO" and set tester mode knob to Park. Outside air door is in 100% outside air, switch plunger has moved out and is not contacting lever.
3. Remain in "LO-AUTO" and set mode knob to A/C. Outside air door changes to 20% outside air, switch plunger is part way out and in contact with lever.
4. If the above changes occurred, transfer switch is operating properly.

If the changes outlined did not occur, with engine running, press system "OFF" button and proceed as follows:

1. Remove the three port vacuum plug from transfer switch and connect a vacuum source to middle port of switch.
2. Depress plunger all the way in and check for presence of vacuum at right port (one closest to lever) and absence of vacuum from left port.
3. Release plunger and check for absence of vacuum at right port and presence of vacuum at left port.
4. If above conditions do not exist, replace switch.