An A/C valve controls refrigerant flow. The expansion valve regulates liquid refrigerant entering the evaporator. Schrader service valves are ports in the lines that allow technicians to hook up gauges to charge or evacuate the system.
Mechanic Glossary
A/C Valve
Any valve in the air conditioning system that controls or regulates refrigerant flow, such as the expansion valve or Schrader service valves.
Frequently Asked Questions
A spring-loaded valve inside the service ports, identical to a tire valve stem, that seals the system but opens when a gauge hose is connected.
The internal valve core has worked loose or its rubber seal is dry-rotted. You can replace the valve core using a core removal tool.
If stuck closed, it starves the evaporator of refrigerant, blowing warm air. If stuck open, it floods the evaporator, which can damage the compressor.