3 - Air-conditioning electrical and electronic control

Abstract

This chapter discusses electrical and electronic control in air-conditioning (A/C) system. It begins with basic electrical principles and then describes a range of sensors and actuators used in common A/C systems. The chapter also describes the underpinning theory associated with sensors and actuators, provides practical examples of their application, and includes wiring diagrams and measured data in various forms representing the output of a sensor or control signal used for an actuator. The sensors used in A/C systems include NTC and PTC temperature sensor; sun load sensors such as photovoltaic diode and solar cells; linear and rotary potentiometer; and metal oxide semiconductor (MOS). Actuators include solenoids, motors, and stepper motors. The chapter describes the design and mode of operation of these sensors and actuators and discusses a wide range of test equipment and approaches available for diagnosing faults on the A/C systems, and explains how to read wiring diagrams. The chapter presents three case studies on the automotive A/C manual control system, the automotive A/C autotemp control system, and the automotive climate control system.