Suction Valves were used on most 60’s and 70’s GM Vehicles. They are mounted to the Evaporator’s suction (top) outlet and regulate system pressures so as to prevent the Evaporator from freezing up.

The STV (Suction Throttling Valve) is a particular kind of Suction Valve used on many 1962-1966 GM vehicles, including the 1964 Grand Prix.

This STV (Suction Throttling Valve) Rebuild Kit includes the valve body diaphragm, O-rings and screen clip.

If you prefer, we can rebuild your 1964 Grand Prix Suction Throttling Valve for you.

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Tech Tip

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 or valve failure. If you are converting to 134a, your Suction Valve will need to be recalibrated as by-pass pressures differ from that of R12. More on converting to 134a.

Air Conditioning Tip

If you are replacing your STV on an otherwise operating system, its failure is likely as a result of contaminants causing it to stick in the open position, forcing it to constantly by-pass. As is the case with any air conditioning system, flushing the system to insure that re-used parts do not contaminate newly replaced or restored parts and replacing or restoring the car’s Filter-Drier are essential to avoid a repeat of the same problem.

A/C INFO:

All car air conditioning systems need a mechanism to keep the Evaporator from getting so cold that it freezes. In some systems, this mechanism is a thermostat. In the 1964 Pontiac Grand Prix’s, it was an STV (Suction Throttling Valve). A thermostat prevents the Evaporator from freezing by cycling the Compressor on and off based on Evaporator temperature. An STV prevents the Evaporator from freezing by by-passing excessive system pressure. Note that in an STV type system like the 1964 Pontiac Grand Prix’s, the Compressor runs constantly whenever the air conditioning system is operating.

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