on a 1991 nissan sentra what does the sensor in the evaporator box do?
It is called an A/C Thermo Control Amplifier. As the temperature is decreasing the circuit opens around 38 to 37° F to turn off the compressor. There is a one to two degree hysteresis in the unit to prevent rapid cycling of the compressor. The device closes the circuit when the temperature reaches 39 to 41°F.
