AC Pressure Switch

How to detect malfunction of the refrigerant pressure sensor

In most cases, detecting a malfunction of the refrigerant pressure sensor requires computer diagnostics at a service station. Special equipment is connected to the vehicle which measures pressure of the refrigerant and oil content in it. If their levels are normal, diagnostics of the component is performed. Malfunction of the sensor-converter is determined using an oscilloscope. Failure of the conventional analog sensor is detected with an ohmmeter, but, for this purpose, the current pressure level in the air conditioner should be known. Low-pressure sensor passes the signal at 1.2–1.4 atmospheres and above, high-pressure sensor - at 20 atmospheres and below.