Peterbilt A/C Expansion Valve

A/C Expansion Valves Meter Refrigerant

An A/C expansion valve controls refrigerant entering the evaporator, where refrigerant absorbs heat from cabin air. A thermal expansion valve responds to operating conditions so the evaporator receives an appropriate flow. It is a metering component, not a cabin temperature knob or an air-door actuator.

Some automotive systems instead use an A/C orifice tube with a fixed opening. The two arrangements are not interchangeable upgrades. A replacement should preserve the metering design used by the air-conditioning system.

Block and Other Valve Connections

Expansion valves can use different body layouts and line connections. A block-style valve incorporates passages for the refrigerant connections in one housing; other designs arrange the sensing and metering elements differently. Mounting, sealing faces, and refrigerant-line positions determine how the valve joins the evaporator circuit.

A refrigerant expansion valve needs the specified metering characteristics as well as the correct connections. Use its application and refrigerant specification together when choosing the replacement.

Front and Rear Evaporator Circuits

Vehicles with separate rear cooling can have a second evaporator and its own metering component. The front and rear units can use different valves and line connections. Identify the circuit being serviced before choosing the part or planning access. Access to a rear unit may involve interior panels rather than the same engine-compartment work used at the front. Plan the parts and seals for the affected circuit.

Frequently Asked Questions