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post #1 of 14 (permalink) Old 07-29-2019, 04:08 PM Thread Starter
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Variable a/c compressor

Has anyone retrofit the variable a/c compressor with a clutch style compressor? Iím done messing around with my variable on my 2009.5 GT . Please pm text it e mail me with any info. 305-951-2715. Thank you. Alex
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post #2 of 14 (permalink) Old 07-29-2019, 07:53 PM
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The only person I know of that has even tried is Ryan Kerr, Not sure if he is on here but he never got it to work, the BCM got real pissy every time he engaged the compressor clutch
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post #3 of 14 (permalink) Old 07-30-2019, 11:32 AM
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It can be done, but not with the original compressor wiring,as the bcm pulse widths the compressor voltage,you will need a straight 12v source to the compressor and retrofit a low pressure switch in the low side pipe so you don't freeze the evaporator

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post #4 of 14 (permalink) Old 07-30-2019, 12:16 PM
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Bench racing here with probably not enough knowlege.

Could a person rig up something with an arduino based module that could be programed to trigger a 12 relay above a certain pulse width?

Add a clutch controlled variable displacement compressor, like 08ish corvette.

In theory, when the bcm commanded low displacment, the compressor would turn off.

Now, a question, what is the issue with our non clutched AC that would drive one to do this?
Too many rpm in modded cars?
Gerry

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post #5 of 14 (permalink) Old 07-31-2019, 12:29 PM Thread Starter
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Thank you all for your input . Does anyone know were the bcm is located. I’m not getting any reference voltage. To the compressor
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post #6 of 14 (permalink) Old 07-31-2019, 01:03 PM
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Also the HVAC module controls comp. not the bcm

2009.5 G8 GT Maverick Silver;Sport/Prem. SunRoof. Nav kit, Vararam,Holden badge kit,Kooks 1 7/8" Headers, VMS Tuned
2009 White Hot G8 GT;Onyx/Red,Sport/Prem,SunRoof, Nav kit,Holden badges,VMS Tuned,Kooks 1 7/8 Headers, Maggie TVS1900, Injection is Great but i love being Blown !
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post #7 of 14 (permalink) Old 07-31-2019, 01:04 PM
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Bench racing ? LOL, I do this for a living with GM, The Corvettes are not variable as far as knowledge goes,It does the clutch on off via press feedback as most, but the G8 comp. is pulse width for variable control. its shaft is always spinning,yes it can be swapped over and no i would leave it as designed as it is very efficient,Yes there is a wide misunderstanding even for some so called professionals for this system.Always get a new GM comp to avoid the problems so stated and you will be fine

1- I said bench racing as I have never done what I was talking about , suggesting emulating the BCM commands with an Arduino

2 - Not, VD ? , might want to check that. Granted they are not PWM controlled, they adjust their displacement based on pressure differentials. I have one in my LS7 powered engine swap Caprice.
Although it has a clutch, if commanded on, it says on, never cycles.

3 - What exactly do you do for a living at GM ? Anything with code writing in E67 ECU's

Thanks

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post #8 of 14 (permalink) Old 07-31-2019, 01:15 PM
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#1 that is not variable, #2 any one can create write code,try and diagnose all this stuff without throwing parts at it is all im saying,or go ahead and replace the whole dam system

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2009 White Hot G8 GT;Onyx/Red,Sport/Prem,SunRoof, Nav kit,Holden badges,VMS Tuned,Kooks 1 7/8 Headers, Maggie TVS1900, Injection is Great but i love being Blown !
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post #9 of 14 (permalink) Old 07-31-2019, 01:18 PM
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Originally Posted by jetmech09 View Post
Thank you all for your input . Does anyone know were the bcm is located. Iím not getting any reference voltage. To the compressor
A Tech II will most likely show you what you need.

The aftermarket ones (VXDIAG VCXNANO) are cheap on Amazon and work very well. It's worth the investment in my opinion considering the fact that the dealership charges one (1) hour of labor at a minimum for anything Tech II related.

https://www.amazon.com/gp/product/B0743BFLXB/

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post #10 of 14 (permalink) Old 07-31-2019, 01:20 PM
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Thank you all for your input . Does anyone know were the bcm is located. I’m not getting any reference voltage. To the compressor
The dark blue wire is the 12 v ref from the hvac module,but if you left it unhooked it will shut the system down and you wont see anything,either remove hvac fuse to reset or remove batt cable to reset,seriously your best bet is hook a tech 2 up and go into body> hvac. for a/c codes after clearing them as a simple outside ambient sensor will cause it not to work comp.

2009.5 G8 GT Maverick Silver;Sport/Prem. SunRoof. Nav kit, Vararam,Holden badge kit,Kooks 1 7/8" Headers, VMS Tuned
2009 White Hot G8 GT;Onyx/Red,Sport/Prem,SunRoof, Nav kit,Holden badges,VMS Tuned,Kooks 1 7/8 Headers, Maggie TVS1900, Injection is Great but i love being Blown !
2001 Trans Am WS6 NBM/Camel, 6Spd 21K Miles
2001 G/P GT
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Last edited by Thawk; 08-01-2019 at 10:03 AM.
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post #11 of 14 (permalink) Old 08-01-2019, 10:06 AM
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1- I said bench racing as I have never done what I was talking about , suggesting emulating the BCM commands with an Arduino

2 - Not, VD ? , might want to check that. Granted they are not PWM controlled, they adjust their displacement based on pressure differentials. I have one in my LS7 powered engine swap Caprice.
Although it has a clutch, if commanded on, it says on, never cycles.

3 - What exactly do you do for a living at GM ? Anything with code writing in E67 ECU's

Thanks
I was the lucky bastard they sent to repair the unfixable electrical demons !

2009.5 G8 GT Maverick Silver;Sport/Prem. SunRoof. Nav kit, Vararam,Holden badge kit,Kooks 1 7/8" Headers, VMS Tuned
2009 White Hot G8 GT;Onyx/Red,Sport/Prem,SunRoof, Nav kit,Holden badges,VMS Tuned,Kooks 1 7/8 Headers, Maggie TVS1900, Injection is Great but i love being Blown !
2001 Trans Am WS6 NBM/Camel, 6Spd 21K Miles
2001 G/P GT
Quote:
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post #12 of 14 (permalink) Old 08-02-2019, 08:50 AM Thread Starter
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Ok. The compressor will work but only after I run the car down the street at a spirited run . Then it works ok till you shut off car. Then do the same again to get it to run. 😳
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post #13 of 14 (permalink) Old 08-02-2019, 09:21 AM
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Ok. The compressor will work but only after I run the car down the street at a spirited run . Then it works ok till you shut off car. Then do the same again to get it to run. 😳
That's because the hvac module sees something out of normal and shuts the system down,If you can get a scanner that reads body fault codes, you will most likely get a code in the Body>Hvac module to greatly help in diagnosing it,matbe buy a technician at a dealership a six pack to scan it with a tech 2

2009.5 G8 GT Maverick Silver;Sport/Prem. SunRoof. Nav kit, Vararam,Holden badge kit,Kooks 1 7/8" Headers, VMS Tuned
2009 White Hot G8 GT;Onyx/Red,Sport/Prem,SunRoof, Nav kit,Holden badges,VMS Tuned,Kooks 1 7/8 Headers, Maggie TVS1900, Injection is Great but i love being Blown !
2001 Trans Am WS6 NBM/Camel, 6Spd 21K Miles
2001 G/P GT
Quote:
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post #14 of 14 (permalink) Old 08-02-2019, 08:55 PM Thread Starter
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Ok. I do have a buddy that has a tech 2. Going to see what codes it shows
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