The suit/ cabin temp control contains two dual section potentiometers. The potentiometers have an outer shaft and control knob for cabin temperature control and an inner shaft and control knob for vent suit temperature control. The cabin temperature control potenti-ometer provides electrical signals to the ACS temperature/ flow controller for automatic temperature control and directly controls the position of the cabin add heat valve for manual temperature control.

AUTOMATIC TEMPERATURE CONTROL

Automatic temperature control is selected by setting the ECS mode switch to AUTO. In the auto mode, the pilot selects the cabin temperature by adjusting the cabin knob of the suit/ cabin temp control. The ACS temperature/ flow controller produces a ref-erence signal in relation to the setting selected on the suit/ cabin temp control. A control circuit in the ACS temperature/ flow controller compares a signal from the temperature sensing element of the cabin airflow/ temper-ature sensor with the reference signal and modulates a control signal to the cabin add heat valve to maintain the selected temper-ature.

MANUAL TEMPERATURE CONTROL

Manual temperature control is selected by setting the ECS mode switch to MAN. In the manual mode, adjusting the cabin knob of the suit/ cabin temp control determines the control signal sent to the cabin add heat valve.

EQUIPMENT COOLING SYSTEMS

Learning Objective: Recognize the source for avionics cooling air; identify com-ponents of avionics cooling systems and the function of each component.

As electronics and avionics in naval aircraft became more common and more sophisticated, it was discovered that the heat generated by this equipment was becoming excessive for proper operation. A means of keeping the avionics at a proper operating temperature was needed. To overcome this problem, some aircraft have. separate ACS for equipment cooling, while others use conditioned air diverted from the environmental ACS. If the equipment ACS is an air-to-air type, its operation is the same as the environmental ACS discussed at the beginning of this chapter. Only operating temperatures will be different. The other type of equipment air conditioning (vapor cycle) operates on the same principal as a home ACS and will be discussed later in this chapter.