The Expansion Valve is mounted at the Evaporator inlet at the bottom of the Evaporator and regulates the refrigerant going into the Evaporator. It reduces the pressure of the refrigerant and creates one of the two divisions between high and low sides in the air conditioning system.

The low pressure side begins with the Expansion Valve and continues through the Evaporator to the Compressor. (The second division is at the Compressor where Compressor suction ends the low pressure side, and the Compressor discharge, releasing compressed refrigerant, is the start of the high pressure side. The high side continues through the Condenser and Filter-Drier back to the Expansion Valve).

The 1963 Pontiac Grand Prix Expansion Valve was a thermostatic Expansion Valve operating off refrigerant temperature. It used a sensing bulb attached to the Evaporator outlet and connected back to the Expansion Valve by a capillary tube to measure Evaporator outlet temperature and then regulated the opening of the Expansion Valve based on that Evaporator outlet temperature. Note, the capillary tube is very sensitive and any kink or repeated bending may cause it to malfunction.

Our 1963 Pontiac Grand Prix Expansion Valve is a new, correct replacement expansion valve.

It has the correct sensing bulb that mounts flat against the under-side of the suction hose fitting, near the evaporator outlet.

COMPATIBLE WITH BOTH R12 & 134a REFRIGERANTS!

More on converting to 134a.

More information on GM Valves?

Don't see what you're looking for? Need technical help? Call or email.