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Run AC through LS1 computer?


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I'm going to be running AC with my LS1 setup in the Z. I'm using the stock harness and is there any advantage to integrating the LS1 harness into the AC system or should I just use the AC controls from the Z? Anyone have any info on this? I did the search but didn't come up with anything regarding AC. THANKS

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Running it through the PCM/harness will allow the engine to compensate for the load of the A/C compressor during idle (especially with automatic transmissions). If you are running a throttle cable the PCM will adjust the idle via the idle control valve (IAC). If you are running a drive-by-wire (DBW) setup there is no IAC and the PCM will just crack the throttle blade to adjust the idle in the same manner the IAC would.

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Cable,

 

Did you use a Speartech harness? If so? how did you hook up the AC? I have 3 wires that are labeled "AC" and have no idea where they are supposed to be connected too. There is a 2 wire connector out by the water temp sensor that doesn't connect to the compressor. Is this for the compressor or maybe the pressure switch? I am using a stock dryer that I think has a pressure switch built into it.

 

Thanks for any light you can shed!

 

Joe

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Cable,

 

Did you use a Speartech harness? If so? how did you hook up the AC? I have 3 wires that are labeled "AC" and have no idea where they are supposed to be connected too. There is a 2 wire connector out by the water temp sensor that doesn't connect to the compressor. Is this for the compressor or maybe the pressure switch? I am using a stock dryer that I think has a pressure switch built into it.

 

Thanks for any light you can shed!

 

Joe

 

I used a modified factory harness from www.Wait4MePerformance.com. I am not running A/C at the moment, but I was told that the bare wire labeled as "A/C" is suppose to connect to the A/C compressor clutch power source so the PCM knows when the A/C compressor has been engaged.

 

Hope that helps.

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I'm going to be running AC with my LS1 setup in the Z. I'm using the stock harness and is there any advantage to integrating the LS1 harness into the AC system or should I just use the AC controls from the Z? Anyone have any info on this? I did the search but didn't come up with anything regarding AC. THANKS

If the LS1 is anything like my LT1 it will be difficult to integrate a different AC system into the harness/PCM. I wanted to do it on my LT1 to allow the idle speed to increase when the system is on, but the PCM won't increase the idle speed unless several criteria are met including evaporator temperature and system pressure values. You can find the specific information required in the Factory Service Manual.
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C'mon guys, someone has to know how to hook up the AC on an LS1 in a 280Z! I'm assuming the "AC Press Sig" and "AC Press GRND" would go to the pressure switch on the drier, correct? The the "AC Comp" under the dash would go to some signal that turns on the compressor but where do I take that from under the dash? If this is correct so far, then the connector under the hood would go to the compressor but the connector doesn't have anywhere on the compressor to plug into. Anyone??

 

Joe

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I do. Problem is this car never came with AC. I have added all of the hardware and could probably find a signal to initialize the compressor but I'd like to use the harness as it was designed. Hopefully Speartech can help.

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I've been running my A/C system on my 280Z without integrating it into the LS1 controls for 6 years now. three of them in the DFW area, and never had a problem. There is so much torque in that motor it doesn't hardly notice the A/C when it kicks on at idle. I think you're chasing something that is inconsequential.

Edited by Phantom
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I've been running my A/C system on my 280Z without integrating it into the LS1 controls for 6 years now. three of them in the DFW area, and never had a problem. There is so much torque in that motor it doesn't hardly notice the A/C when it kicks on at idle. I think you're chasing something that is inconsequential.

I even went to the extent of wiring in potentiometers for required temperature and pressure voltages my LT1 PCM expects to make the system think the AC was engaged to kick up the idle all to no avail (although it would work if I adjusted the pot’s while the system was running).

 

All that being said, I still would like to raise my idle when the compressor is engaged. I like to run a low idle, but when the compressor is running he idle is too low even though I have quite a bit of torque. If anyone comes up with a good way to raise the idle (only when the compressor is on) I’d love to hear about it.

 

I thought about trying to hook up a universal throttle solenoid like this one: http://www.jegs.com/i/Holley/510/46-74/10002/-1 but I haven’t sold myself on the idea yet.

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I really didn't know that all of the AC wires from the ECU were sensing signal only. Now that I have figured that out by tracing the wires to the ECU and checking pins with the Camaro FSM, I can see whats going on. Still have to trace that plug that is out by the compressor to see what that is looking for.

Now the task at hand is running wires out to the pressure switch and compressor. Also, wire in the AC relay. Looking at the Datsun FSM it seems I can bypass both vacuum mag switches and just have the pressure switch in front of the relay.

I'll keep this thread updated once everything is thought out.

 

Joe

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