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Thread: A/C Wiring with HP EFI

  1. #1

    Default A/C Wiring with HP EFI

    I looked over the wiring manual but can't find a definite answer.
    Is there a dedicated wire in the Holley harness for the A/C function or do you have to use one of your I/O?

    If there is a dedicated wire, is it for WOT?

    The best I can determine is that it's a disable function to turn A/C off during WOT.

    I definitely want to maintain a WOT relay as well as a pressure switch.

    I just plan on running hot wire from A/C controls (inside car) to the the pressure switch on the accumulator, then to the relay (blade 30) that sends power to the AC clutch.

    Mainly need to know the function of the A/C wire coming out of the Holley HP.

    Is the A/C wire coming from the Holley is normally a ground signal that removes signal under WOT condition? If it is I can just use that for the trigger ground (blade 85) on the relay. That way the relay would be closed during normal operation and would open and kill the circuit to the A/C clutch under a WOT situation.

    This is what I have in mind:


  2. #2
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    Quote Originally Posted by TxFireman1972 View Post
    Is there a dedicated wire in the Holley harness for the A/C function or do you have to use one of your I/O?
    It's not a specific wire in the harness, and yes, it does utilize one of your Outputs.
    There's an "A/C Shutdown" & "Max TPS" parameter (in Basic I/O - System Parameters), to disable the A/C at WOT.
    The A/C Shutdown "Output Type" (in Inputs/Outputs - System Parameters) can be +12V or Ground activated.

    Enable it & Pin-Map to an available J1 connector output pin; click "View Outputs" on the Pin Map.
    (Click & drag it to an available J1 Connector pin.) Now you can run this wire to the relay.
    A relay must be used because all the ECU's Outputs are rated at a maximum of 2 amps.

    The 558-400 I/O Auxiliary Harness connects up to 4 Inputs & 4 Outputs to the EFI main harness.
    Eight Wire I/O Auxiliary Harness Connector Pin-Out (also in the Holley EFI Wiring Manual Link):
    Pin A...A12...White/Blue (Input #1)
    Pin B...A3...White/Red (Input #2)
    Pin C...A13...White/Black (Input #3)
    Pin D...A4...White/Green (Input #4)
    Pin E...B12...Gray/Yellow (Output #1)
    Pin F...B11...Gray/Red (Output #2)
    Pin G...B10...Gray/Black (Output #3)
    Pin H...B3...Gray/Green (Output #4)

    You're actually programming the ECU to assign a specific function to that pin/circuit.
    It doesn't have a specific assigned pin; it's any available Output pin, according to which Output Type you selected.
    Don't worry, the EFI software won't allow you to make a mistake with the Pin Map.
    http://www.holley.com/data/TechServi...0Pin%20Map.pdf (Pin Map Instructions)

    If the I/O menu icon (ICF) isn't already uploaded (added) to the top Toolbar, follow these instructions:
    (This same procedure applies to all the various Individual Configuration menu icons/items.)
    The "I/O" function is an "Individual Configuration" of the Holley EFI software.
    At top of screen, Click "Toolbox" and "Add Individual Config".
    At top of new window, select "Individual Configuration Library".
    At bottom of new window, select "Holley EFI Inputs/Outputs Config".
    Select "I/O" and open "Base Config - Blank.io".
    The "I/O" icon will then be present at top of screen.

    This is what I have in mind:
    The A/C Shutdown Output becomes active (+12V or Ground), above the MAX TPS/Coolant Temp setting.
    So depending on your vehicle's wiring, you may need the relay to be normally open or normally closed.
    All of the five terminal relays listed below, have a normally open and a normally closed contact.

    It's nothing special, although for ECU wiring, a relay with a resistor or diode (across the coil) should be used.
    It's a typical five terminal automotive relay (Bosch/Tyco) that can be obtained at your local auto parts store.
    The first five relays listed below, are all the same five terminal SPDT configuration, with bracket & resistor:
    Tyco V23234-A1001-X043
    Bosch 0 332 209 161
    Hella 87420
    Pico 5591PT (Relay/Wiring Kit)
    Echlin/Napa AR143 (Wiring Kit)
    Echlin/Napa AR204 (50 amp, diode protected - correct wiring polarity required.)

    If you don't want to concern yourself with the correct wiring polarity, just use a resistor type relay (no polarity wiring matters).
    For diode relays, the relays have a schematic diagram on their side. Follow the directions below regardless of relay manufacturer:
    +12V - Cathode
    Ground - Anode

    http://www.autoshop101.com/forms/hweb2.pdf
    (Diode vs. Resistor Relays - Page 12 & 13)

    EFI Software Help Information/Instructions:
    ‒ On the top Toolbar, click "Help" & "Contents". This opens all Help topics.
    ‒ When navigating the software, click "Help ?", drag it to any parameter and click again.
    ..This automatically opens the definitions for that specific parameter.
    ‒ Tuning information can be read by clicking the F1 key, when you're viewing any screen.
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual & Diagrams)
    http://documents.holley.com/techlibrary_199r10544.pdf (Holley EFI Help/Instructions Overview)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  3. #3

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    Awesome, that's exactly what I was thinking. Thanks as always!

  4. #4

    Default

    This is an old thread I started. Never ended up doing it on that car. I have another car now, and just got all of my Holley HP EFI stuff in the other day. This is how I'm planning on wiring up the A/C WOT cutout relay to the Holley HP. Look good to you?

    This would have power (positive) coming into the relay from the A/C pressure switch to the common (30). Negative from the Holley EFI on WOT to one side of the coil (86), and positive from switched 12 volt to the other side of the coil (85). This would give power to the normally closed (87a) under non-WOT operation, which would engage the A/C clutch and would open under WOT condition, which in turn would disengage the A/C clutch.


  5. #5
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    Quote Originally Posted by TxFireman1972 View Post
    This would have power (positive) coming into the relay from the A/C pressure switch to the common (30). Negative from the Holley EFI on WOT to one side of the coil (86), and positive from switched 12 volt to the other side of the coil (85). This would give power to the normally closed (87a) under non-WOT operation, which would engage the A/C clutch and would open under WOT condition, which in turn would disengage the A/C clutch.
    Yes, that seems correct. Since the A/C Shutdown output is active above the Max TPS % value.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  6. #6
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    I used one of the programmable I/O to shut the A/C off. That way you can have it deactivate the A/C compressor below 500 RPM. So it's not on when you start the car. Here's a Global File, if you want to see what I did. It's V4.
    Attached Files Attached Files

  7. #7
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    Default

    Quote Originally Posted by 81 TransAm View Post
    I used one of the programmable I/O to shut the A/C off. That way you can have it deactivate the A/C compressor below 500 RPM. So it's not on when you start the car.
    I just posted up some very similar questions. Thanks for the OP and to 81TransAm for posting his Global File. That really helped me understand how to accomplish this same thing on my '85 Mustang.

  8. #8

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    I use the HVAC head unit in the car to send a +12V request to the Holley HP (type "H" Input) to let me know when A/C is being requested. That wire is in series with the high & low pressure switches, so that the A/C request is disabled when line pressure goes out of spec. I then use that Input to trigger a custom Output that operates the A/C compressor clutch relay, and that wire also goes to a custom Input for the Holley A/C "IAC Kick" feature to keep the car from dying at idle when the A/C clutch is turned on. I also have dual radiator fans that are controlled by a custom Output (each), so I can change the fan strategy when A/C is active. I did this so I can have full control of the A/C compressor & fan strategy. The following logic is what I used with A/C control, but your imagination is the limit.

    * A/C active only when engine speed is >600 RPM. This disables compressor clutch during engine startup and is well below my 900 RPM idle speed.

    * A/C active only when engine speed is <4000 RPM. There is no value to wear out the compressor at high RPM. Just watching TPS isn't enough because you might let off throttle after a spirited run and you don't want A/C switching on at high engine speed.

    * A/C active only when TPS is <50%. This disables A/C to free up some horsepower when I'm driving hard.

    * 1 second timer to delay activation. This is a debounce so I can move the HVAC controls in the car without A/C blipping on & off when I sweep through HVAC modes.

    * I would also like to delay A/C after first startup, so engine can settle before a load is applied, but I haven't figured that out yet.

    * Turn on a cooling fan whenever A/C is being used.
    Last edited by Qwktrip; 10-16-2016 at 12:37 PM.

  9. #9

    Default IAC Kick setup for LS3 & Vintage Air.

    I'm new to the forum & EFI and was hoping to get some help in setting up an IAC Kick function to keep my engine from shutting off when the A/C compressor kicks on. I understand I need a relay, but I'm a bit lost after that. I have the Holley HP EFI system and I've located the I/O connector. From the research gathered on the forum, this in my understanding of what's needed.
    1. Run wire from pin #30 to A/C trinary switch (not sure which side of the switch).
    2. Run wire from pin #87 to compressor 12V.
    3. Run wire from pin #85 to Holley EFI connector (not sure which pin in connector to use).
    4. Pin #86, not sure how to wire this one.
    Is this correct? Thanks in advance for your help.

  10. #10
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    The A/C "IAC Kick" function doesn't require a relay. It's just an A/C Input from the compressor clutch, and can be programmed as a "+12V" or "Ground" Input Type (Inputs/Outputs tab, in System Parameters ICF).

    The A/C Shutdown function requires a 5-terminal changeover relay (NO & NC contacts) to interrupt the A/C clutch wire, momentarily disabling the A/C at WOT as programmed. The A/C Shutdown output is active above the Max TPS % value. You can change the Output Type to "+12V" (Inputs/Outputs tab, in System ICF) for relay coil terminal #86, so the relay coil terminal #85 can be simply grounded. Then terminals #30 & #87A open to interrupt the A/C clutch wire.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

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