Results 1 to 14 of 14
  1. #1
    Join Date
    Jul 2007
    Location
    Tracy, CA.
    Posts
    1,348

    Default Vintage Air Trinary switch wiring, PSI harness

    I'm sure this has been covered 1000 times already, but I am trying to figure out how to wire the trinary switch for my VA system. I have a PSI harness with 2 wires for the fans, but how do I incorporate the trinary switch to turn on one of the fans without interrupting the ECM? this is an LS3 swap, Griffin Radiator, twin fans with PSI harness.

    Thanks for any help that you can provide...did I mention that I hate wiring!
    Steve Martin
    67 Camaro RS
    66 Chevelle

  2. #2
    Join Date
    Sep 2004
    Location
    San Antonio, TX
    Posts
    211
    Country Flag: United States

    Default

    I'm not familiar with the PSI harness, but brushed fans are typically operated by relays. The relays are typically switched on the ground side. Most ECMs also use "active low" outputs for fans which means they ground the outputs when fans are required, activating ground side switched relays and turning on the fans. If you are wired in this way, you'll simply ground one side of the VA trinary switch (blue) and hook the other side (also blue) up in parallel with the ECM output. This way, either the ECM or the trinary can trigger the fan relay. They won't interfere with each other.

    Ryan









    Quote Originally Posted by class67 View Post
    I'm sure this has been covered 1000 times already, but I am trying to figure out how to wire the trinary switch for my VA system. I have a PSI harness with 2 wires for the fans, but how do I incorporate the trinary switch to turn on one of the fans without interrupting the ECM? this is an LS3 swap, Griffin Radiator, twin fans with PSI harness.

    Thanks for any help that you can provide...did I mention that I hate wiring!
    KUL FIR CHICK N: COOL FIRECHICKEN
    '68 Firebird, LS7, 6spd, DSE all around.

  3. #3
    Join Date
    Sep 2004
    Location
    San Antonio, TX
    Posts
    211
    Country Flag: United States

    Default

    Sorry guys, I just realized I had an error on the wire color for the trinary switch. I have already corrected it above. The blue wires on a VA trinary switch are the fan trigger circuit and the black/green wires are the AC pressure safety switch circuit. Sorry for the confusion.

    Ryan
    KUL FIR CHICK N: COOL FIRECHICKEN
    '68 Firebird, LS7, 6spd, DSE all around.

  4. #4
    Join Date
    Jun 2010
    Location
    Deployed
    Posts
    2,331
    Country Flag: United States

    Default

    Correct, you have the trinary operate a relay via ground activation. I have two fans, one is controlled by the ecm and the other is wired to the trinary switch and a thermal switch on the radiator.
    1970 Camaro/DSE build


    Are you driver enough? Maybe....come on blue!
    http://www.pro-touring.com/threads/1...71#post1147371

  5. #5
    Join Date
    Nov 2006
    Location
    Mountain Springs, Texas
    Posts
    2,412
    Country Flag: United States

    Default

    Quote Originally Posted by badazz81z28 View Post
    Correct, you have the trinary operate a relay via ground activation. I have two fans, one is controlled by the ecm and the other is wired to the trinary switch and a thermal switch on the radiator.
    You never give it up, do you? Seriously it can also be used to switch a 12 volt signal just as easily as a ground depending on the design that someone is implementing...

    SMH,
    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1969 Camaro convertible - LS3 4L65E Ridetech Level 2 Tru-Turn - sold
    1959 El Camino project
    1969 Mustang Sportsroof project
    1956 Cameo project

  6. #6
    Join Date
    Sep 2004
    Location
    San Antonio, TX
    Posts
    211
    Country Flag: United States

    Default

    Quote Originally Posted by dhutton View Post
    You never give it up, do you? Seriously it can also be used to switch a 12 volt signal just as easily as a ground depending on the design that someone is implementing...

    SMH,
    Don
    Agreed. It's just a switch. You can use it how you wish, as long as the rest of the fan harness is set up properly. We have seen plenty of folks with the fans wired-up improperly to the AC system that cause the compressor to engage when it's not supposed to. This typically happens when people don't have a trinary switch and are triggering the fans off the compressor clutch power lead.

    Ryan
    KUL FIR CHICK N: COOL FIRECHICKEN
    '68 Firebird, LS7, 6spd, DSE all around.

  7. #7
    Join Date
    Nov 2006
    Location
    Mountain Springs, Texas
    Posts
    2,412
    Country Flag: United States

    Default

    Quote Originally Posted by KUL FIR CHICK N View Post
    Agreed. It's just a switch. You can use it how you wish, as long as the rest of the fan harness is set up properly. We have seen plenty of folks with the fans wired-up improperly to the AC system that cause the compressor to engage when it's not supposed to. This typically happens when people don't have a trinary switch and are triggering the fans off the compressor clutch power lead.

    Ryan
    Thanks for weighing in. Hopefully it will reduce some of the confusion leading to these wiring errors. Maybe VA should incorporate some kind of fan control option or module in your systems...

    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1969 Camaro convertible - LS3 4L65E Ridetech Level 2 Tru-Turn - sold
    1959 El Camino project
    1969 Mustang Sportsroof project
    1956 Cameo project

  8. #8
    Join Date
    Jul 2007
    Location
    Tracy, CA.
    Posts
    1,348

    Default

    Ok, so what I have done is wired up another SPAL FRH relay as follows:
    Red - to fan
    Orange - 12v switched
    Yellow - 12v bat
    grey - wired to the compressor

    Will this work? and do I absolutely need to wire up temp sender as well? if so, just tie into the grey wire, correct?
    Steve Martin
    67 Camaro RS
    66 Chevelle

  9. #9
    Join Date
    Nov 2006
    Location
    Mountain Springs, Texas
    Posts
    2,412
    Country Flag: United States

    Default

    Not following this. Where is the trinary switch?

    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1969 Camaro convertible - LS3 4L65E Ridetech Level 2 Tru-Turn - sold
    1959 El Camino project
    1969 Mustang Sportsroof project
    1956 Cameo project

  10. #10
    Join Date
    Sep 2004
    Location
    San Antonio, TX
    Posts
    211
    Country Flag: United States

    Default

    Grey goes to one of the blue wires on the trinary and the other blue goes to chassis ground. This will ground the grey wire when AC head pressure reaches 254psi, closing the relay contacts and turning on the fan. You don’t have to wire in the temp switch, but I would. Just tie it in with the grey. The switch grounds when it reaches its set point.

    Ryan
    KUL FIR CHICK N: COOL FIRECHICKEN
    '68 Firebird, LS7, 6spd, DSE all around.

  11. #11
    Join Date
    Jul 2007
    Location
    Tracy, CA.
    Posts
    1,348

    Default

    That's what I thought, thank you for the confirmation!
    Steve Martin
    67 Camaro RS
    66 Chevelle

  12. #12
    Join Date
    Mar 2013
    Location
    Sunny Calif
    Posts
    132
    Country Flag: United States

    Default Bad trinary switch

    Quote Originally Posted by KUL FIR CHICK N View Post
    Grey goes to one of the blue wires on the trinary and the other blue goes to chassis ground. This will ground the grey wire when AC head pressure reaches 254psi, closing the relay contacts and turning on the fan. You donít have to wire in the temp switch, but I would. Just tie it in with the grey. The switch grounds when it reaches its set point.

    Ryan
    this is the set up i used as well with V/A and psi harness, all worked well unit the elec servo heater valved started the tick of death, V/A was tech was quick to ship one out to me as it has been an issue in the past. unfortunately for me it went out at the exact time my trinary switch took a dump and would not engage my a/c pump clutch and in my frustration ordered it before calling to see if V/A would warranty it. oh well it 102* around here these days and would rather have my part sooner than later. Has anyone else ever had a trinary switch go bad?

  13. #13
    Join Date
    Sep 2010
    Location
    Beach Park IL
    Posts
    2,190
    Country Flag: United States

    Default

    I have seen one in the past 20 years.......a wire broke off where it is soldered on to the switch under the rubber cap. That's the only one I have had fail.
    Donny

    Support your local hot rod shop!

  14. #14
    Join Date
    Mar 2013
    Location
    Sunny Calif
    Posts
    132
    Country Flag: United States

    Default

    peeled back the rubber cap and no solder detaching issues just would not see pressure to close connection to engage the compressor, swapped out trinary today, will have to get a vac draw on it and fill with to factory recommended specs. while system was down moved the condenser closer to the radiator, 1" from almost 1.75" in hopes to bump air flow across it.





Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •