# Air Lift/Dual Compressor/Wiring Help Needed



## Grifnsqest (Sep 22, 2005)

So I'm a bit stuck. Maybe someone can help...

I am getting ready to install the Air Lift Autopilot V2 equipment in my Touareg, but I can't seem to confirm the correct wiring for the control pad, manifold, and two compressors. So I wanted to run it by you first, to make sure I understood it correctly. For the most part, I'm confused about how the previous owner had it wired through a single 90A relay, compared to running dual 40A relays like I've seen in various schematics.


Here's where I'm at...


From the control pad...
Black AL005 goes to ground
Red AL004 goes to a switched 12V source (I plan to use the rear cigarette lighter 12V power wire)
White AL025 goes to white AL025a on the manifold

From the manifold...
White AL025 goes to the control pad
Black AL005 goes to ground
Gray AL006 goes to terminal #85 of the relay
Pink AL004 goes to terminal #86 of the relay (which I am hoping can be combined with the same signal as the Red AL004 from the control pad)
Grey/White AL034 goes to terminal #85 of the relay (sharing the same signal as Gray AL006, I hope)

From the single 90A relay...
Terminal #87 provides 12V source for each compressor (2-10gauge lines running to it)
Terminal #30 goes to a fused (40amp) positive supply line to the battery (or should it be higher given 2 compressors??)
Terminal #85 goes to both Gray&Gray/White lines
Terminal #86 goes to a switched 12V source? (Or directly to 12V constant??)

To make things even more confusing, the single 90A relay still had Terminal #30 with a pair of cut wires still attached, both being black 10gauge wires. That lead me to believe a pair of ground wires, most likely for the compressors, were plugged in here.

The original owner is no help, as he did not do the install. I currently have an email out to the shop that did the install, as well as Air Lift. Whoever gets at it first will earn 25 Cool Points!!!

So any help or suggestions would be GREATLY appreciated.

Thanks yall!!!


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## rgarjr (May 19, 2012)

On the 90A relay

30 goes to 12V positive (Battery)
87 goes to the 2 positive leads for the compressors
85 is your Comp Signal (should ground itself when the V2 activates it)
86 goes to 12V ignition power

On the manifold

AL034 you don't need to connect to anything
AL04 yes that's your ignition input


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## Grifnsqest (Sep 22, 2005)

So #85 still gets the solid gray al006... correct?


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## [email protected] (Jan 25, 2008)

You never want to run V2 with dual compressors on a single relay. Get me your email addy and I will send you the correct wiring diagram.


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## Grifnsqest (Sep 22, 2005)

[email protected]


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## Grifnsqest (Sep 22, 2005)

Yeah... I have that schematic. Thank you for sending it.

The previous owner ran a single 90A relay for 2-3yrs. Why do you think that was successful? Or was it just a risk he was willing to take??


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## [email protected] (Jan 25, 2008)

Grifnsqest said:


> Yeah... I have that schematic. Thank you for sending it.
> 
> The previous owner ran a single 90A relay for 2-3yrs. Why do you think that was successful? Or was it just a risk he was willing to take??


It was for sure a risk. Many people think it is just easier to run one relay, what they do not realize is running a set up like that can cause damage to the manifold.


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## MechEngg (Jan 13, 2009)

Why is that Jeremy? Is the amp draw from the coil too high for the manifold? Would it just be easier to make the next version compatible with a higher amp rating so that people can actually run a single relay? Give the customers choices in installation instead of giving them only one or two ways to set it up and your system will go a long way :thumbup:


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## Grifnsqest (Sep 22, 2005)

I went ahead and picked up a pair of 40A relays on the way home today, just to play it safe. But, I must admit, I still don't understand why running one large relay would be bad...?

Once a compressor kicks on, it can only demand X. The other compressor, when it kicks on, will also demand X. If one compressor dies, I don't think the other compressor gets 2X. Right????


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## SKIDMRK (Sep 15, 2001)

Well, if a compressor dies, it will normally pop a fuse. If you're using one big relay, and one big fuse for two electronic components, there is the possibility that you will not have the proper protection for your vehicle as it might not pop the fuse for the larger load/fault. 

Having two relays and a fuse for each makes sure that each is properly protected. Not only the compressors, but your vehicle too. Also, if a compressor dies, you have a separate compressor on a separate circuit that will continue to be operational. 

I've seen a lot of people just run two compressors off of a big stinger relay and have no issues. But I'd rather take the safe route, spend a little more, do a bit more wiring, and guarantee that I will never have major issues.


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## Grifnsqest (Sep 22, 2005)

I went ahead and ran two separate relays. No sense in taking a chance...

Thanks for all the help !!!

As soon as I get everything done, I'll post in here.

If you get bored, you can check out my progress in the Southwest Forum...


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## rollback50k (Oct 25, 2009)

SKIDMRK said:


> Well, if a compressor dies, it will normally pop a fuse. If you're using one big relay, and one big fuse for two electronic components, there is the possibility that you will not have the proper protection for your vehicle as it might not pop the fuse for the larger load/fault.


Same reason a car has more than one fuse, it just wouldn't be safe.


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## Sideout (Jan 29, 2003)

Grifnsqest said:


> I went ahead and picked up a pair of 40A relays on the way home today, just to play it safe. But, I must admit, I still don't understand why running one large relay would be bad...?
> 
> Once a compressor kicks on, it can only demand X. The other compressor, when it kicks on, will also demand X. If one compressor dies, I don't think the other compressor gets 2X. Right????


We have a few reasons why running compressors in this fashion is not ideal. First, each compressor will have a large "inrush current" of ~35A. Triggering both at the same time is very hard on both the battery and alternator due to this quick hit of current. Secondly, the piston of whichever compressor was on it's down stroke will have to work much harder during the first few seconds of running. We have found that firing them both simultaneously for long periods of time can cause premature wear of the cylinder walls and piston seals. 

The way a V2 operates is to first enable the Gray wire (AL006) then after a 500ms delay, enable the Gray/White AL034) wire. This is to make it more gentle on both the compressors and charging system.



MechEngg said:


> Why is that Jeremy? Is the amp draw from the coil too high for the manifold? Would it just be easier to make the next version compatible with a higher amp rating so that people can actually run a single relay? Give the customers choices in installation instead of giving them only one or two ways to set it up and your system will go a long way


On our V2 design, we are able to flow upwards of about 2A before the output is maxed out, with no more than 1.5A for long periods of time. Normally the coil of a single relay will draw ~500mA, while a solenoid (or high amp relay) will require anywhere from 3-5A to activate. We have a few reasons why we will not let the system do this, two of which are listed above. The third being that it would add a substantial increase in price and size to our wiring harness, as well as the risk associated with a much larger wire that is able to flow a ton of current. If a customer installs the harness incorrectly and without a fuse, the risk of property damage increases exponentially. Trust me, I've seen some haggared installs 


In summary, do not connect Gray and Gray/White together to run a solenoid as it could damage the PCBA. Run two separate relays, one triggered by Gray and the other Gray/White. Use two fuses, one for each compressor. Oh and do not ground the compressors to the body, make sure they have a direct wire to the battery. Following these steps will ensure the best performance and life out of your system :thumbup:


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## Grifnsqest (Sep 22, 2005)

Well, I will have to do some more rewiring...

After getting an email from Jeremy, I went ahead and rewired the controller and manifold. I have one direct line (fused) from the fuse box to the controller, which then continues on to the manifold. But, that hasn't seem to solve the ECU BOOT message that is constant.

However, this is the first I'm seeing a sensitive issue with the compressors needing to be grounded to the battery, rather than directly to ground. So, I will have to do that.

If that doesn't solve my issue, I don't know what else to do...

Any other suggestions on how to resolve this ECU BOOT message???


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## beachbum718 (Mar 22, 2015)

So I have 2 relays that came with my pair of compressors. The second compressor harness from v2 and v2 main harness.is that all I need? Do I need a 100 amp fuse with power line ran to trunk with a power line splitter?

Email is [email protected]

For diagrams .it would help alot thx


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## Grifnsqest (Sep 22, 2005)

I ran two lines, 40a fuse on each line. Its my understanding that each compressor demands 30A at peak. So a 40a per line should be safe. I wouldn't do 100a and split.


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## Grifnsqest (Sep 22, 2005)

Followed the advice from the gentlemen at Airlift and ran some new ground wires for the compressors, as well as the manifold. Guess what happened...??





Magic!!!


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