What is the function of vacuum controlled actuators.
Vacuum motors move the various doors to direct the airflow to the proper vents. Vacuum air doors are controlled by a selector switch in the control head. This unit directs the vacuum signal to the proper motor.
Vacuum system malfunction.
If the selector switch is defective, vacuum will not be supplied to the proper door. If there is a leak in the vacuum system, the door wills not move properly due to no or a low vacuum signal. A vacuum leak anywhere in the control circuit will affect the operation of the entire system.
How to test a vacuum controlled door actuator.
If the system is sound, the vacuum motor should be checked. When testing a vacuum actuated door, the vacuum gauge readings should remain steady for at least one minute. If the gauge reading drops slowly, the actuator is leaking and should be replaced