Suction Valves

(Hot Gas, Suction-Throttle, POA & VIR)

What is a suction valve?

The suction valve is found on most 60’s and 70’s GM vehicles. There are several different types, generally varying by model year as follows:

The first three are all different kinds of suction valves. They are mounted to the evaporator’s suction (top) outlet and regulate system pressures so as to prevent the evaporator from freezing up.

The Valve-In-Receiver is a POA valve, drier, and expansion valve all in one. It too is mounted on the Evaporator.

Why restore my suction valve?

A good indication that your suction valve has failed or is failing is a high low-side system gauge reading. This is either as a result of contaminants locking the valve or clogging the valve up or valve failure. If you’re converting to 134a, your valve will need to be properly calibrated as by-pass pressures differ from that of R12. More on Converting to 134a!

It is hard to find new replacement, NOS and NORS models of the various GM suction valves so Classic Auto Air offers restoration services for each.

Hot Gas Valve Restoration

We can restore your GM hot gas valve.

Hot Gas By-Pass Valve rebuild consists of:

• Disassemble, inspect, clean and replace damaged or missing parts.
• Zinc plate all external pieces
• Install new seats & O-rings
• Assemble & test

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Suction Throttling Valve Restoration (STV)

We can restore your GM suction throttling valve.

Suction Throttling Valve (STV) rebuild consists of:

• Disassemble, inspect, clean and replace damaged or missing parts
• Install new internal diaphragm & O-rings
• Assemble & test