There is a low pressure cycling switch on your old accumulator(silver looking can on the evapator unit) that you can use for the AC request signal to the PCM. There is also a high pressure switch from your trans-am (a 3 wire pressure sensor) that you will need to install on your system so the PCM can sense the pressure. I had mine hooked up this way at first, then I found out I have the variable displacement compressor so I didn't need the low pressure switch. If this doesn't make sense to you I can take pictures. As for EGR they eliminated it with the cam profile on the newer models, but I don't think it would cause any engine harm to run without it.
2006 Superior Blue Trailblazer SS AWD, Stock as a rock
Sold: 2002 GMC Sportside Denali front end with a 2002 LS1, FLT level 5, Yank 2600, Trick Turbo, T76, Nelson intercooler, 60LB injectors, Warbro fuel pump, Eaton locker, Magnaflow, 3.42, Nelson Performance Tuning (speed density).
Sold: 1981 GMC LB RC 1500 2002 4.8L 4L60E 12 bolt 3.73 Richmond Lock Right AC PS Nelson Performance tuning
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