harascho

Hi, I guess I need a little help from the pros...

You will remeber my 2007 5.3 LMG swap into my 1997 Tahoe. It's time to set up the AC system. As long as we don't have a way to generate the AC request signal on the CAN bus and use the '07 AC pressure sensor and the E38 to do the work we have to work around this issue.

I have the AC Compressor (internal variable displacement from a 2007 6cylinder GM truck..) on the Kwik bracket kit lined up ( I had quite a few alignment issues.. pics follow..). I made custom AC hoses on the basis of the OEM 2007 Tahoe hoses ( some aluminum welding required..) now its time for the wiring.

The 1997 system has a pressure cycling switch (close to the service port on the compressor), a high pressure switch (back of the compressor) and another pressure switch on the receiver/drier (I guess that's the one for the recirculation motor..).

Ok the cycling switch and the pressurer switch at the drier are NO with no pressure applied. My question now is, does the normal refrigerant charge build enough pressure to close the cycling switch so that it's function is to open when the pressure rises above a certain value, or is it the other way round that the cycling pressure switch stays open until the pressure is too high and then it closes?


any ideas??
Harald

LS1GMCTruck

iTrader: (2)

To start with, you must have an "A/C Request" signal from the computer to initiate the compressor cycle, if you want the computer to control the A/C(which everyone recomends). On your year vehicle, this computer request wire ties directly into the request wire coming from the dashboard control panel. Using computer control, you will also need to install a '99-'02 Camaro three-wire cycling switch into your hi-pressure return hose/line that leads from your condenser in front of the radiator, to your evaporator under the dash. Another A/C computer control wire, comes from the computer to your A/C power "on" relay, which is in your power-center under the hood on the drivers side. With this wiring system incorporated, there is no need for the use of your old low-pressure side switch on your accumalator/dryer, from your old system. I don't know that you can use the new compressor in the fashion that the old compressor was used. Someone else may know possibly. Hope this helps.

dsrour

I didnt find Harald's question confusing at all. The response did show a lack of understanding of how the E38 handles AC. The AC request comes by way of the LAN. On earlier computers from cars that had manual AC as an option there was provison for AC request which was a simple 12volt signal from the AC switch on the dash.
As far as I know no one has come up with a work around for this yet. I posted a question earlier regarding use of the C6 a/c module to generate an AC request signal. No definitive answer yet.
I'm not famailiar with the working of GM variable displacement compressors, so cant help you there.

chandler melia

I am dealing with the same issue. I swapped the new 2010 5.3L into my 1997 2dr yukon and we are having a hard time hooking up the a/c system. Did you ever figure it out? What is your email, I can send you everything I have tried. We used a sanden 508 with a trinary switch on high side. I had custom hoses made and left the low-pressure cycling switch intact on the dryer. Did not work.