2002 C5 Z06, AC wont work without scan tool?
09-01-2016, 03:55 PM
#1
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2002 C5 Z06, AC wont work without scan tool? Hey guys,
I was hoping you could help me out. I'll try to give as much info.
I have a 2002 C5 Z06 with a recently replaced LS6 motor, stock except for a cam. The previous motor had a serious issue and was removed, replaced with this new one. The ECU from the previous motor was tuned with HP tuner and kept to use with the new LS6 replacement.
The AC now does not work. I have had the car tuned (again with HP tuner). My mechanic that installed the new LS6 says he cant figure out how to get the AC to work all the time, but can get it to work when it's hooked up to a Scan tool.
Sounds to me like its computer/software related, but im a novice at this stuff.
Anyone have any advice?
I was hoping you could help me out. I'll try to give as much info.
I have a 2002 C5 Z06 with a recently replaced LS6 motor, stock except for a cam. The previous motor had a serious issue and was removed, replaced with this new one. The ECU from the previous motor was tuned with HP tuner and kept to use with the new LS6 replacement.
The AC now does not work. I have had the car tuned (again with HP tuner). My mechanic that installed the new LS6 says he cant figure out how to get the AC to work all the time, but can get it to work when it's hooked up to a Scan tool.
Sounds to me like its computer/software related, but im a novice at this stuff.
Anyone have any advice?
09-06-2016, 02:54 PM
#4
from my 2002 gm service manual for camaro/firebird, it states the PCM will prevent air conditioning (grounding the AC clutch relay) when things like engine coolant is greater than 250°F, engine rpm I think over 5000, but also has general statements such as "torque load".
So if the PCM has been modified and various things have either been wiped out or deactivated, it would not surprise me that deep down in the programming a condition is now NOT being met as a result which in turn causes the PCM to not turn on the AC compressor under what would be normal conditions.
other of reflashing the pcm back to oem, the simplest/easiest thing to do would be to tap off pin # ?? from the pcm that is the AC clutch relay which is how the PCM activates the compressor, and run it to a toggle switch somewhere in the cabin that you can control manually.
the one downside that comes to mind when controlling it manually like this is now you would effectively be bypassing the low pressure sensor- whose purpose is to prevent compressor failure when there's a low refrig. condition.
So if the PCM has been modified and various things have either been wiped out or deactivated, it would not surprise me that deep down in the programming a condition is now NOT being met as a result which in turn causes the PCM to not turn on the AC compressor under what would be normal conditions.
other of reflashing the pcm back to oem, the simplest/easiest thing to do would be to tap off pin # ?? from the pcm that is the AC clutch relay which is how the PCM activates the compressor, and run it to a toggle switch somewhere in the cabin that you can control manually.
the one downside that comes to mind when controlling it manually like this is now you would effectively be bypassing the low pressure sensor- whose purpose is to prevent compressor failure when there's a low refrig. condition.
