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Thread: Trianary AC switch tie-in to cooling fan with Coyote

  1. #1
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    Trianary AC switch tie-in to cooling fan with Coyote

    My 33 build has the 5 L Coyote, and following the install PDF I tied the radiator fan to the be controlled by the engine computer. Now I am completing the AC system install, and Vintage Air provided a trianary safety switch. Designed to kick on the radiator fan if the AC system reaches a PSI set point. Has someone already done this? Any concerns with signal or power interference with engine computer.

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    I have the Coyote in my MK4 and Whitby's Vintage Air AC. The PDB (Power Distribution Box) has a small relay in it to turn on the fan when the AC relay is energized in the PDB. To keep this from happening so the Trinary switch can control the fan, one of two things has to be done. Use the AC relay and remove the small relay on the PDB PWB or take away the fan control from the PCM. I removed the small relay and used the trinary switch and PCM to control the fan. The way I wired it allows the fan to be controlled by engine temperature through the PCM and through the trinary switch. I also have the Infinity Box wiring so some of what I did will not apply to you. I condensed the wiring for the trinary switch to the schematic attached. Grounding the PDB BEC pin A-12 turns on the fan via the fan relay in the PDB. The 12V AC relay shown is the AC relay in the PDB controlled by a switch not shown in this part of the schematic.
    mk4_schematic_vehicle_pg1.jpg

    The Ford Racing Controls Pack documentation included a schematic and pin out of the connectors mentioned above. If you don't have that, PM me and I can send a copy to you.
    Last edited by 2bking; 08-30-2015 at 01:54 PM.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

  3. #3
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    Quote Originally Posted by 2bking View Post
    I have the Coyote in my MK4 and Whitby's Vintage Air AC. The PDB (Power Distribution Box) has a small relay in it to turn on the fan when the AC relay is energized in the PDB. To keep this from happening so the Trinary switch can control the fan, one of two things has to be done. Use the AC relay and remove the small relay on the PDB PWB or take away the fan control from the PCM. I removed the small relay and used the trinary switch and PCM to control the fan. The way I wired it allows the fan to be controlled by engine temperature through the PCM and through the trinary switch. I also have the Infinity Box wiring so some of what I did will not apply to you. I condensed the wiring for the trinary switch to the schematic attached. Grounding the PDB BEC pin A-12 turns on the fan via the fan relay in the PDB. The 12V AC relay shown is the AC relay in the PDB controlled by a switch not shown in this part of the schematic.
    mk4_schematic_vehicle_pg1.jpg

    The Ford Racing Controls Pack documentation included a schematic and pin out of the connectors mentioned above. If you don't have that, PM me and I can send a copy to you.
    I am in process of following your solution. The small relay in the PDB appears to be fixed to the board. How did you remove it. If I just tie into the A-12 wire, is it necessary to remove the small relay?

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    Quote Originally Posted by roblegrow View Post
    I am in process of following your solution. The small relay in the PDB appears to be fixed to the board. How did you remove it. If I just tie into the A-12 wire, is it necessary to remove the small relay?
    The relay has to be removed to keep the AC relay from energizing the fan. The little relay energizes the fan relay when the AC relay is energized. I unsoldered mine but you could destroy it using small wire cutters. Cut through the middle of it carefully and keep trimming until it is removed.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

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    I need help with interfacing the Ford Coyote A/C compressor to the Gen II Vintage Air System I bought from FFR as an option. No one at Vintage Air, Factory Five or Ford Racing has any knowledge of the problem. I have found that the Ford compressor wiring schematics from Ford show the power coming from a relay, (in our case its from the trinary switch) going to pin 1 on the Ford pigtail and pin 2 is supposed to be grounded. Sounds simple, however if you do a simple bench test with a 12.5 vdc power source to the connector when you touch the ground wire back to the negative of the battery you get a dead short. That is what I anticipated due to an ohm check showing no resistance between power and ground. The Ford schematic shows a relay output going to pin 1 of the connector and pin 2 to ground. I have been to my Ford Racing dealer and taken a new compressor from stock with same results! I have done the PCB mods suggested by 2bking and got the cooling fan to engage at 180F and the trinary switch is taking power A-12 of the PCB, I had no ground in the Ford harness to the cooling fan and have corrected that malady now I'm stumped. I have attached 2 Ford docsFord Compressor Pigtail 001.jpgFord schematic of power source and ground to compressor clutch 001.jpg Help!

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    Quote Originally Posted by 2bking View Post
    I have the Coyote in my MK4 and Whitby's Vintage Air AC. The PDB (Power Distribution Box) has a small relay in it to turn on the fan when the AC relay is energized in the PDB. To keep this from happening so the Trinary switch can control the fan, one of two things has to be done. Use the AC relay and remove the small relay on the PDB PWB or take away the fan control from the PCM. I removed the small relay and used the trinary switch and PCM to control the fan. The way I wired it allows the fan to be controlled by engine temperature through the PCM and through the trinary switch. I also have the Infinity Box wiring so some of what I did will not apply to you. I condensed the wiring for the trinary switch to the schematic attached. Grounding the PDB BEC pin A-12 turns on the fan via the fan relay in the PDB. The 12V AC relay shown is the AC relay in the PDB controlled by a switch not shown in this part of the schematic.
    mk4_schematic_vehicle_pg1.jpg

    The Ford Racing Controls Pack documentation included a schematic and pin out of the connectors mentioned above. If you don't have that, PM me and I can send a copy to you.
    I followed this up to two points Are you using the ford PDB to power the ac? If so how? Second what would be the problem with the fan coming on when the ac turned on?

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    First of all, this only applies to the 2013 version, the 2015 is different.
    Yes, I'm using the AC relay in the PDB. It is energized by the PCM when +12V is applied to the pink blunt lead the goes to Pin 7 on the 15 pin connector in the PDB. The fan is controlled by grounding pin A12 in the BEC connector. I spliced into this circuit and ran it to the trinary switch; the PCM controls the fan through this circuit also. I chose to let the pressures in the AC system (sensed by the trinary switch) determine when the fan came on rather than having it run continuously. The fan may not be needed continuously when the weather is cooler or on the highway. I suspect Ford wanted it to run when AC was selected because not all cars have a trinary switch. The PCM usually monitors the AC pressure to control the fan and compressor clutch but the PCM that comes with the Coyote has been dumbed down to eliminate a lot of functions.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

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    Thanks I have the 2012 version of the control pack. Right now I'm running the compressor clutch off the trinity switch the other side comes from the vintage air signal. So if I attach the other leads of the trinity switch the blue to ground and and pin A12 in the BEC connector will this control the fan? Sorry if Im not following you.

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    Quote Originally Posted by 48prerunner View Post
    Thanks I have the 2012 version of the control pack. Right now I'm running the compressor clutch off the trinity switch the other side comes from the vintage air signal. So if I attach the other leads of the trinity switch the blue to ground and and pin A12 in the BEC connector will this control the fan? Sorry if Im not following you.
    Sounds like you have it correct. PM me and I will send the schematic showing the trinary as I wired it. I tried to attach it here but it exceeded the size limits.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

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    The clutch problem is solved, with the help of Michael Everson who had a spare clutch assembly. He checked the resistance across the coil of the clutch and it showed 4.4 ohms and with a battery he verified the clutch would engage. Michael was so kind to ship it to me and it fixed the problem. My new compressor had a shorted coil, we powered it up after it was disassembled it got very hot quickly. Ford Racing Technical support could not help with any spec, neither could Vintage Air of FFR technical support.
    Now I need to charge the system, the cooling fan will engage now at 180F after finding the ground wire to the fan was open circuit. The brakes now feel firm and stop the car well, I did not move the rear wheel calipers to 3 o'clock when I bled them, it is important on Willwoods!

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    I am not the best at wiring and could use an easy and understandable way to wire the trinity switch. 2013 ford control pack for coyote with vintage air.

  12. #12
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    Quote Originally Posted by 1932 View Post
    I am not the best at wiring and could use an easy and understandable way to wire the trinity switch. 2013 ford control pack for coyote with vintage air.
    The trinary switch has two switches that open and close based on the pressure in the AC high pressure line. One of the switches operates the fan and the other the AC compressor clutch. Here is a portion of a page from my schematic which shows the Trinary and Vintage Air temperature switch and PDB reference is the 2013 Coyote controls pack. The noted wire colors are what were on my trinary switch. The noted pressures are approximate from my memory so the actual pressures may be higher or lower. The BLK/GRN wires are to the switch that has to have about 30 psi to close (a fully charged system) and opens at something over 300 psi (A problematic system) and operates the AC compressor clutch. The blue wires go the switch that operates the fan and it closes at something over 150 psi, the point at which the AC needs the cooling fan to operate at max efficiency. Hope this helps.
    trinary.jpg
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

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    Thanks King i get that but what to do at BDB. Splice into or undo a-12 wire and is it the small black relay? asking for help is better than letting the smoke out!

  14. #14
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    Quote Originally Posted by 1932 View Post
    Thanks King i get that but what to do at BDB. Splice into or undo a-12 wire and is it the small black relay? asking for help is better than letting the smoke out!
    The AC relay that I removed is the small orange one shown in this picture on the left side and I assume it is the "small black relay" you're asking about.
    DSCF4571d.jpg

    It is removed in this picture:
    DSCF4592d.jpg

    The PCM grounds the wire coming from the BEC connector at position A-12 to turn on the fan based on the engine temperature. You need to splice into that wire and run it to the Trinary so the fan relay can also be controlled by the AC mode. If you want a switch on the dash to turn on the fan, this is the wire to splice into for that too; ground it using the switch.
    King
    Roadster #8127, ordered 7/12/13, received 9/11/13
    http://thefactoryfiveforum.com/showt...4-Coyote-Build

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    That is the info i needed. A picture is worth a thousand words!
    Thank you very much!

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