Enter your username:
Do you want to login or register?
  • Forgot your password?

    Login / Register



    Results 1 to 3 of 3
    1. #1
      Join Date
      Oct 2004
      Posts
      109

      Trinary switch adapted onto a metric A/C port?

      I'm putting a Vintage Air underdash unit in my '74 International pickup. I'm also swapping out the old AMC 258 motor for a Jeep stroker 4.0L. I have all the factory Jeep A/C components from a 2000 Cherokee, which should fit nicely but I've run into a problem. I plan to run a trinary switch on the factory Jeep drier. The trinary switch I have (and all those I see for sale) use 7/16-20 threads. The drier has a male M10-1.25 male port with a Schrader valve inside.

      Does anyone know where to find an adapter between these two? Preferably with a Schrader valve in case I ever need to replace the switch? Or, is there a way to wire up the factory low and high-pressure switches to essentially do the same thing? Thanks!



    2. #2
      Join Date
      Oct 2004
      Posts
      109
      I may have answered my own question with the right combination of google search terms. The 2000-01 Cherokee had a low-pressure switch in series with a dual function high-pressure switch that will control an electric fan. I'll have to verify the cut-off numbers are consistent with the Vintage Air requirements but I think this should do it!

      "OPERATION

      The low pressure cycling clutch switch is connected in series electrically with the high pressure cut-off switch, between ground and the Powertrain Control Module (PCM). The switch contacts open and close causing the PCM to turn the compressor clutch on
      and off. This regulates the refrigerant system pressure and controls evaporator temperature. Controlling the evaporator temperature prevents condensate water on the evaporator fins from freezing and obstructing air conditioning system air flow.
      The low pressure cycling clutch switch contacts are open when the suction pressure is approximately 141 kPa (20.5 psi) or lower. The switch contacts will close when the suction pressure rises to approximately 234 to 262 kPa (34 to 38 psi) or above. Lower ambient
      temperatures, below approximately -1° C (30° F), will also cause the switch contacts to open. This is due to the pressure/temperature relationship of the refrigerant in the system. The low pressure cycling clutch switch is a factory calibrated unit. It cannot be adjusted or repaired
      and, if faulty or damaged, it must be replaced.

      DUAL FUNCTION HIGH PRESSURE SWITCH (4.0 L) DESCRIPTION

      The Dual Function High Pressure Switch controls both A/C clutch engagement/disengagement, and electric cooling fan operations. The switch is located on the discharge line near the compressor. The switch is screwed onto a fitting that contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant system. The discharge
      line fitting is equipped with an O-ring to seal the switch connection.

      OPERATION

      The dual function switch is connected in series electrically with the low pressure cycling clutch
      switch between ground and the Powertrain Control Module (PCM). The switch contacts open and close causing the PCM to turn the compressor clutch on and off. This prevents compressor operation when the discharge line pressure approaches high levels, and also reduces electrical surging from compressor clutch engagement. The dual function switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the discharge line pressure drops to 1600 kPa (235 psi). The dual function switch controls the A/C clutch operation by disengaging the clutch when the discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The switch contacts will close and allow A/C clutch engagement when the discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi). The Dual Function High Pressure Switch is a factory- calibrated unit. The switch cannot be adjusted or repaired and, if faulty or damaged, it must be replaced."

    3. #3
      Join Date
      Apr 2001
      Location
      The City of Fountains
      Posts
      15,971
      Country Flag: United States
      Quote Originally Posted by Stupidnewbie View Post
      I may have answered my own question with the right combination of google search terms. The 2000-01 Cherokee had a low-pressure switch in series with a dual function high-pressure switch that will control an electric fan. I'll have to verify the cut-off numbers are consistent with the Vintage Air requirements but I think this should do it!

      .....The dual function switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the discharge line pressure drops to 1600 kPa (235 psi). ...
      This seems pretty close to the VA trinary fan switch, which I believe is 265psi.

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
      Instagram @projectgattago
      Dr. EFI
      I deliver what EFI promises.
      Remote Holley EFI tuning.
      Please get in touch if I can be of service.

      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her



    Advertise on Pro-Touring.com