Pressure Relieve Valve On A/C Compressor, Checking

WARNING:

There is a danger of ice-up.

Pressure relief valve will drain refrigerant with engine running and high pressure in refrigerant circuit.

Turn engine off.

Fig 1: A/C compressor pressure relief valve

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

The pressure relief valve -arrow- has operated when refrigerant oil is found in the close vicinity.
In this case, vehicle must be taken to an A/C specialist workshop. Refer to REFRIGERANT CIRCUIT, SPECIALIZED REPAIRS .