Ambient Temperature Sensor / Switch HVAC: Description and Operation

The ambient sensor is attached in front of the driver's side condenser. It detects ambient temperature and converts it into a resistance value which is then input into the auto amplifier. The automatic amplifier includes a "processing circuit" for the ambient sensor input. However, when the temperature detected by the ambient sensor increases quickly, the processing circuit retards the auto amp. function. It only allows the auto amp. to recognize an ambient temperature increase of 0.33 °C (0.6 °F) per 100 seconds. As an example, consider stopping for a cup of coffee after high speed driving. Although the actual ambient temperature has not changed, the temperature detected by the ambient sensor will increase. This is because the heat from the engine compartment can radiate to the front grille area, location of the ambient sensor.

Auto amplifier controls compressor operation by ambient temperature and signal from ECM.




Low Temperature Protection Control

Auto amplifier will turn the compressor "ON" or "OFF" as determined by a signal detected by ambient sensor.
When ambient temperatures are greater than 1 °C (34 °F), the compressor turns "ON". The compressor turns "OFF" when ambient temperatures are less than -2 °C (28 °F).