need some A/C help

[Chevydillan]

Im using my original 97 compressor on a 2004 5.3 and running a 242 ecm from the donor Tahoe. The truck had been previously 411 swapped with the old L31 and the A/C worked just fine. I reworked the original harness and don't remember messing with anything A/C related. problem is the compressor will not turn on, its properly charged and all that the compressor is just not receiving any signal from whatever its needs a signal from.
Now, using my HP-Tuners I can turn the compressor on with the VCM controls and it all works just fine that way. how do I make the truck tell the new ecm to turn on the compressor? Its way to hot here not to have a working A/C.

[Chevydillan]

Did some checking and C2-17 which is A/c request is getting 12v when A/C is turned on inside truck. C2-55 low pressure switch signal changes when I unplug the low pressure sensor( I don't remember what it changed to though ) C2-43 compressor clutch relay control never sends out the ground needed to turn on the relay. Of course when I turn on the compressor with HP-Tuners C2-43 sends out the ground needed and compressor turns on.
What does the computer need to see in order to turn on the relay?

[Chevydillan]

Double post

[Lextech]

The 2004 A/C calibration will not work with a 97 truck. Your 2004 A/C Type is a Type1 and you need a Type3 calibration.

Jeff

[Chevydillan]

Jeff, do I just need to bypass the computer all together then? Looks like I should be able to add a relay triggered by C2-17 to give the ground to C2-43 and it should work. It's to bad the computer won't turn on the compressor, I noticed that fans even turn on when the compressor is running thanks to the pressure switch near the compressor. I'll keep messing with it and see what I can do.

[Lextech]

You have to excuse me----I can't remember everybody's different setups. You installed the 3 wire pressure sensor at the compressor??? If so, your tune needs to be changed to A/C Type2. I wouldn't add anything electrical. Just fix the tune.

Jeff

[Chevydillan]

No Jeff. I didn't install anything different, there is a sensor in the pressure line coming out of my compressor that turns on the fans. Where in hp-tuners do change the a/c type?