Blackpony

iTrader: (6)

Is there a wire i can send power or ground to that lets the computer know the a/c is on? i am having trouble getting the idle just right on my ls swap setup.

Also does anyone have any issues with major vibration of the compressor using an r4 compressor? at 800 rpms I am getting this huge vibration and the compressor is bouncing like crazy and causing a loud noise. thinking i should have went with a sanden compressor..

Blackpony

iTrader: (6)

I am guessing pin 14 on the green connector is what i send a signal to to activate the fans, idle etc? I have an 05 truck harness.

garys 68

iTrader: (1)

I'm pretty sure the later trucks use a serial line signal to the ecu.
I've been running my LS conversions without AC enable signals to the ecu with no problems. For the fan, I use the temp activation from the ecu and a trinary switch to activate with high AC refrigerant pressure.

Blackpony

iTrader: (6)

Right now I am just using the factory wiring and ac activation for the compressor with a wire tapped into the relay to turn on the fans. I think my problem is the compressor having such a large load on the engine.

BP Automotive

iTrader: (3)

The newer trucks to use the data line to provide the A/C clutch status signal. However, I have had great results using the cavity on the green connector. Cavity 18 is the clutch status signal on the Blue/Red pcm. If you look at the pinouts for the auto trans trucks you will find it says it is unused. Granted I cannot guarantee it will work on 100% of all applications of the Blue/Green PCM. I have done it this way many, many times and never had it not to work.

So tap on the the 12v signal to the compressor clutch and run it to green 18.

Blackpony

iTrader: (6)

Excellent thanks!!

hookemdevils22

iTrader: (12)

BP Automotive - I'm assuming you plug into pin 18 on the red connector, as a pinout I have shows the blue pin 18 as being for the trans fluid pressure switch. The pinout also shows blue pin 35 as 'clutch switch signal', and red pin 17 as 'AC request signal'.

I might actually tap into one of these if I ever take my wiring apart again, since I'm not running an AC signal and the car sometimes dies coming down to idle with the AC on.

BP Automotive

iTrader: (3)

Yes, on the blue/red pcm the clutch status signal is red 18. On the blue/green pcm the pinouts for green 18 say unused for the vortec. However, this is the clutch status for those PCMs. (in my experience).

bczee

iTrader: (12)

I don't use any signal on my swap.. the engine will sometime idle down a bit on stopping, but it has never died on me. But then I don't drive around and slamming on the brakes for the most part !.

I might someday try to take the clutch signal to pin Red #18 as BP suggested.

Thanks for the info on the Clutch signal and pin Red #18.

BC

BP Automotive

iTrader: (3)

Red 17 is A/C request. That would be the signal from your Climate Controls. Red 18 is the Clutch Status signal. It just gets 12v whenever your compressor is on. Here is a diagram for ya. This is a stand alone style A/C wiring diagram with low pressure switch.

Blackpony

iTrader: (6)

Very good info here, thanks for sharing!!