For 1990-2009 cars

Important: Service fitting caps are the primary seals for the service fitting valves. They must be installed and tightened with O-ring seals in place to prevent refrigerant leak.

The A/C refrigerant system has a high pressure (discharge) and a low pressure (suction) service fitting valve. These valves provide access to both sides (high and low pressure) of the system. Always replace the protector cap on the service fitting valves after servicing the A/C system to prevent refrigerant from escaping.