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1960s mustang evaporator, will the TXV valve work with R134?

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  • 1960s mustang evaporator, will the TXV valve work with R134?

    Creating a custom A/C system for my 1955 buick, has a 1995 GM H6 compressor, new universal condenser and dryer. I found a nice 1965 or so mustang under dash evaporator unit with a TXV valve on it. Will this TXV valve work with R134 or should I swap it out? Do these valves fail from sitting, so maybe it is junk regardless?

  • #2
    The Tx valve will work fine with 134a, it doesn't care about the refrigerant (within reason) its only job is to meter that refrigerant such that all the liquid boils by the exit. It does this by comparing the temp just after the Tx to the temp at the evaporator exit.
    They can corrode and stick if left open for long periods. I have used them successfully after sitting open for decades, but you have to be prepared to draw the system down again if it doesn't work. Up to you if you think it is worth the chance.
    My advice would be to use the largest (capacity) parralle flow condenser you can fit behind the grill. It will compensate for the slightly less capacity of the 134a.


    • #3
      Thanks, I did get a R134 condenser as big as the radiator. I will try out the TXV and see how it goes.


      • #4
        Ok, The valves that need re setting or adjustment when changing refrigerants are the POA, STV and EPR (Gm/Ford, Ford and CHRY respectively) Systems that use these valves, don't use a frost switch to cycle the clutch to restrict how cold the evaporator can get, they use the valves to restrict how low the pressure (and thereby the boiling point) to limit how cold the evaporator can get. With R 12 and R 134a having a slightly different boiling point pressure at 32 deg, need to have the valve set to the refrigerant used. Tx valves don't limit how cold the evaporator can get and don't need to be reset.


        • #5
          also is there a way to bench test the TXV before doing this? I just feel like sometimes the old OEM stuff is better than what is sold today as new, and if this one is good why install a new part that is junk. It has happened to me before with reproduction parts.


          • #6
            Not really, it would be hard to re create the operating conditions on the bench.


            • #7
              ok, thanks!