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How does the A/C request and pressure sensors work exactly?

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YOUR RESEARCHHow does the A/C request and pressure sensors work exactly?

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Check hvac a/c request signal

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Suggestion · Original poster

I also don't have an oscilloscope to check the HVAC A/C request signal.

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How does the A/C request and pressure sensors work exactly?
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Leading evidence: 'Check hvac a/c request signal' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check hvac a/c request signal' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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Check hvac a/c request signal

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Suggestion · Original poster

I also don't have an oscilloscope to check the HVAC A/C request signal.

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How does the A/C request and pressure sensors work exactly?
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POST 1 / ORIGINAL POSTEROriginal post

I'm going through the motions of a custom standalone for my swap, but I am at a loss with regards to understanding the details of the 996.1 A/C system. The schematics show the HVAC sends A/C request to the DME which sends compressor ON to the clutch. Does anyone know what sort of signal that HVAC is sending? 12v+ or -? Is it a square wave or something else? Also, I can't find for the life of me where the A/C hi/low pressure sensors terminate in this schematics... If the HVAC cuts out A/C request based on pressure sensors all on its own, then I can just take its A/C request out and manipulate it to turn on the clutch on its own. I'm not sure if that's the reasonable play here because I don't know what ingests the pressure sensor signals. I also don't have an oscilloscope to check the HVAC A/C request signal. FYI, this is for a '99 996.1

POST 2 / ORIGINAL POSTEROriginal post

Ignore. I found this: https://www.renntech.org/topic/46394...oubleshooting/ . I also was able to determine the schematics taking a closer look.

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