Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Pressure SwitchThe A/C pressure switch consists of a high-low pressure switch (A/C pressure switch A) and a middle pressure switch (A/C pressure switch B).
- High-low pressure switch
If the refrigerant pressure becomes too high (due to blockage or lack of airflow at the A/C condenser), or too low (due to leakage), the A/C pressure switch stops the A/C request and the signal to the ECM and the A/C compressor stops operating.
- Middle pressure switch
If the refrigerant pressure goes above 1,470 kPa (15.0 kgf/sq.cm, 213 psi), the A/C pressure switch closes to signal the ECM to change the speed of the A/C condenser fan and radiator fan (high). When the pressure drops to 1,080k Pa (11.0 kgf/sq.cm, 156 psi) the switch opens and funs return to low speed.