AC setup in GENIV swap into 1997 Tahoe

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05-10-2009, 09:07 AM
harascho

AC setup in GENIV swap into 1997 Tahoe

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
05-10-2009, 12:04 PM
GasGuzzler

On the 97 you have a cycling switch on the accumulator (receiver/dryer). This opens when the pressure on the low side is too low. Most from this era use 12 volts through this switch in the relay engage circuit. The switch in the back of the compressor opens when high side pressure gets too high. Not sure what the third is (although I know it's not the cycling switch). I cannot use GM service info for non-engine wiring on anything older than 98 so I'll have to look it up tomorrow to see what you mean.

Either way you should be able to temporarily hot wire the pressure cycling switch to get compressor operation. The main problem is the way the 07 makes enabling decisions.
05-10-2009, 01:31 PM
harascho

switches

Hi.. and I thought the cycling switch is on top of the '97 compressor on the hose connection block?

For sure the high pressure cutout switch is in the back of the compressor.

As far as I read the pressure switch on the receiver / drier is the low pressure cutout switch....??

hmmmm

Harald
05-10-2009, 01:34 PM
harascho

Quote:

Originally Posted by GasGuzzler

On the 97 you have a cycling switch on the accumulator (receiver/dryer). This opens when the pressure on the low side is too low. Most from this era use 12 volts through this switch in the relay engage circuit. The switch in the back of the compressor opens when high side pressure gets too high. Not sure what the third is (although I know it's not the cycling switch). I cannot use GM service info for non-engine wiring on anything older than 98 so I'll have to look it up tomorrow to see what you mean.

Either way you should be able to temporarily hot wire the pressure cycling switch to get compressor operation. The main problem is the way the 07 makes enabling decisions.

What do the '98 / '99 schematics say.... it should be basicly the same setup...

Yes you are correct.. to get the system running correct the AC request signal is necessary on the CAN bus....

Harald
05-10-2009, 11:07 PM
GasGuzzler

No CAN bus and most all AC function on that old dog is either 12v or 5v.
05-11-2009, 01:42 AM
harascho

can

Quote:

Originally Posted by GasGuzzler

No CAN bus and most all AC function on that old dog is either 12v or 5v.

Correct, but I was thinking loud about the 2007 system...
Harald