Thermostatic Air Cleaner Vacuum Switch: Description and Operation

THERMAC Operation:

PURPOSE
Senses incoming air temperature and modifies vacuum signal to the vacuum motor accordingly

LOCATION
In the air cleaner assembly.

OPERATION
When the temperature is below 30° C (86° F), the sensor allows vacuum to be applied to the vacuum motor and the damper door opens the hot air passage, closing the cool air pasage.
As the temperature rises, the bi-metal spring on the sensor begins to react to the heated air, opening an air bleed. By opening the air bleed, lees vacuum is supplied to the vacuum motor and the door begins to change positions. When the air temperature reaches 55° C (131° F) the sensor completely opens the air bleed and no vacuum is applied to the vacuum motor. The door closes the hot air passage and opens the cool air passage.
The sensor then cools and the process begins again. The sensor regulates the temperature between 30° C (86° F) and 55° C (131° F).