Plug and Play 1228062 swap to 1227747 A/C Issue

[dave w]

Link to 1228062 Info: http://www.gearhead-efi.com/Fuel-Inj...Information-4E

Link to 1227747 Info: http://www.gearhead-efi.com/Fuel-Inj...Information-42 (4.3 Auto .bin files in post 4 and post 5)

dave w

[damanx]

Not sure why wipers aren't working because the 7747 and 8062 ECM's don't have anything to do with the wipers. (I could be incorrect)

The A/C clutch signal from the ECM goes to the relay for the A/C clutch, or at least that is how my ECM is wired.

[stew86MCSS396]

Is no one else having this issue or is it because some/most people that do a V8 S10 swap originally w 8062, they ditch the A/C...there problem fixed!!!

I have an unmolested AKDX 747 that can try but as stated in post #1 S-T auto is what dictates which wiring scheme you'll have. AKDX does not meet that criteria. In fact unless I'm not seeing it, none of those bins listed fits "S-T auto."

There's not much on the internet about this dilemma but found this on TGO... https://www.thirdgen.org/forums/diy-...1228062-a.html

All other internet hits...all allude to upgrading to a PCM but if I'm understanding this correctly if you're replacing a 8062 S10 auto bin or even a 288 S10 auto bin for that matter you're going to run into this same issue. Suppose you could add the fan control to PCM and use that to cycle the relay for the compressor clutch.

Looking at the schematic it clearly shows an A/C cycling switch so I don't see any harm de-pinning A2 and permanently grounding it unless someone tells me otherwise.

[Fast355]

Is no one else having this issue or is it because some/most people that do a V8 S10 swap originally w 8062, they ditch the A/C...there problem fixed!!!

I have an unmolested AKDX 747 that can try but as stated in post #1 S-T auto is what dictates which wiring scheme you'll have. AKDX does not meet that criteria. In fact unless I'm not seeing it, none of those bins listed fits "S-T auto."

There's not much on the internet about this dilemma but found this on TGO... https://www.thirdgen.org/forums/diy-...1228062-a.html

All other internet hits...all allude to upgrading to a PCM but if I'm understanding this correctly if you're replacing a 8062 S10 auto bin or even a 288 S10 auto bin for that matter you're going to run into this same issue. Suppose you could add the fan control to PCM and use that to cycle the relay for the compressor clutch.

Looking at the schematic it clearly shows an A/C cycling switch so I don't see any harm de-pinning A2 and permanently grounding it unless someone tells me otherwise.

IIRC it is a normally closed relay, meaning the ECM grounds the relay to disable the A/C. The relay is more for WOT a/c shut-off than it is for anything else. It may also kick the compressor off if it enables and the engine idle rpm dips to low to prevent stalling.

From GM the 7747 never controlled the a/c clutch.