ac wiring

[70inbville]

Does a person need to leave the ac related wires in the harness for recognition of the computer? I have been looking at the pin out stuff at lt1swap and a/c related wires are said to not be needed. I am going to run vintage air in my truck on a 6.0 and don't want to take out wire from the harness that I need.

Thanks,

Chip

[LockDoc]

Originally Posted by 70inbville

Does a person need to leave the ac related wires in the harness for recognition of the computer? I have been looking at the pin out stuff at lt1swap and a/c related wires are said to not be needed. I am going to run vintage air in my truck on a 6.0 and don't want to take out wire from the harness that I need.

Thanks,

Chip

I was debating that too. I have an under dash air unit. I went ahead and removed them thinking the system could be stand alone.

LockDoc

[70inbville]

Thanks for the reply, I just don't want to take away the computers ability to protect the compressor at higher rpm's. SO much to consider when doing this swap, and how it all fits together. I'm about to wear out the search here, thanks to all for the great info.

[ls1nova71]

Originally Posted by 70inbville

Does a person need to leave the ac related wires in the harness for recognition of the computer? I have been looking at the pin out stuff at lt1swap and a/c related wires are said to not be needed. I am going to run vintage air in my truck on a 6.0 and don't want to take out wire from the harness that I need.

Thanks,

Chip

It can be done either way, but a lot depends on what year and OS you're using. 99-02 trucks are pretty simple, and require a high and low pressure sensor. 03-06/7 are serial data A/C request, but can be changed now with tuning software to be like the older trucks. 98-02 F body requires a 3 wire pressure sensor. That said, it really doesn't need to be run through the PCM. If you're worried about over-revving the compressor, then just reach up and turn the A/C off before getting crazy racing anybody. Your original A/C system didn't have any protection of that nature and they survived.

[70inbville]

Thanks guys for the info.

[LockDoc]

Originally Posted by 70inbville

Thanks guys for the info.

x2

LockDoc

[homemade87]

I have a 04 silverado system . I used the 82 controls to turn it on. I am also using the 82 low pressure switch just like the truck came with so if I loose pressure it will shut off.

On the other hand I did use the computer to control the high pressure side with the trinary switch from the 04 system. This is what controls the fans and over pressure. It controls the dual fans set up just like factory. On when needed off when not. All controlled by the trinary. This also created a delay for the compressor and fans at start up.

I also have the engine temp controlled by the pcm . Once you get up to about 35 mph the fans are no longer needed so they shut off (engine and a/c). They will come back on if needed above that speed . It all worked out good for me.

[plumber452]

I just ran across this old thread and was wondering how you got the serial data line to "Tell" your PCM that you were requesting A/C

[prodjay10]

I believe you gotta use the factory ac panel from the donor to get the serial data to work.

[plumber452]

I have the HVAC Module/Panel from an 05 Avalanche and the dash harness for it. I also found a pinout chart for the wiring but not exactly sure which wires to use. When I put 12 volts to the constant 12volt wire(Orange) and 12volts to the Ignition Wire(Brown) and tie the Ground(Black) together I get 3 volts going out of the serial data wire(White) The voltage doesn't change when I push the A/C button. Does this sound right? Is there some other wires I need to connect? I'm doing this on the bench not on the truck with all the A/C plumbing and low pressure sensor hooked up. I'm just trying to sort all of this out before I actually start my swap.

[ls1nova71]

Originally Posted by plumber452

I have the HVAC Module/Panel from an 05 Avalanche and the dash harness for it. I also found a pinout chart for the wiring but not exactly sure which wires to use. When I put 12 volts to the constant 12volt wire(Orange) and 12volts to the Ignition Wire(Brown) and tie the Ground(Black) together I get 3 volts going out of the serial data wire(White) The voltage doesn't change when I push the A/C button. Does this sound right? Is there some other wires I need to connect? I'm doing this on the bench not on the truck with all the A/C plumbing and low pressure sensor hooked up. I'm just trying to sort all of this out before I actually start my swap.

Do you have the PCM hooked up to it? Are you looking at data with some kind of scanner? If not, then you're probably not going to be able to figure it out. The serial data wire sends a serial data message from the A/C module to the PCM, it doesn't change the voltage. You need to have it all hooked up and see if the PCM is receiving the "turn on the A/C" message from the dash module. It will then determine if factors such as engine temp, throttle position, A/C line pressure, ect say its ok to then command the A/C relay to send 12v to the compressor.

[plumber452]

Thanks for the info. No, I do not have the module hooked up to the PCM. That makes me feel better that I might have it right after I get all of the components in and the system charged so the PCM is seeing pressures, etc. I've attached the pinout of the HVAC module. Could you look at and tell me what wires I need to make it operate just to send the A/C request? I've really enjoyed following your builds and I'm trying to duplicate a lot of your work.

[87chevy.com]

Dont you just need to change the ac request in hp tuners and no need for donor ac panel?
Second, it's best to have the ecu control the ac period. No idle.hunting issues, bogging or shifting issues with the ac on. Not sure why ppl are afraid of integrating it. Simply wire it like the diagrams show.

[plumber452]

The guy that I used to remove the VATS, etc from my PCM said the only way that he was aware of to have the PCM control the A/C was through the HVAC module. He mentioned that he had thought about getting a module and "Disecting" it to see what it would take to make a controller to achieve the A/C request. That was before I saw the RPM Extreme device. My guy uses HP Tuners as well.