A/C issue - Aristo ECU control

[Satan]

Okay, so I finally figured out the issue with my A/C compressor's clutch not kickin' on. Seems that the ECU is no longer supplying the ACMG signal. I wired it up, like the pic below. I have searched and searched and not found the original thread talking about doing it this way.

Since it's no longer working, I am trying to get one of my spare ECUs back (lent them to some locals), but am wondering if I can undo the mod and it work as it should, without the ECU controling the signal to the magnetic clutch. I used a spare "bad" ECU I still have to test and am positive the ECU is the issue. The bad spare throws out about 10 codes, but still starts the engine and the clutch is kicking on as it should. I just can't reliably use this ECU.

Anyone know for sure, if I can just reconnect the wires that were cut in the pic and if it will work fine, or is there some potential issue that way?

Specs - Aristo 2JZ engine & ECU in MKIII

Thanks,
E

 

[Satan]

....any reason why I shouldn't just reconnect the brown wire? At least to re-charge the A/C until I swap the ECU?

 

[tissimo]

I used the A/C Amp singal to the ecu to let it know the clutch was on, increasing the idle. The ecu didn't actually control the clutch the MKIII A/C Amp did. Worked perfect, 650 rpm a/c off 800 rpm a/c on.

This was with a 92 Aristo harness & ecu in a 91 car.

 

[Satan]

^^I can't find the original thread or what the pros/cons are to just hooking the brown wire back together. I need A/C soon and the capacitors I ordered aren't here yet, to hopefully fix the ECU.

Basically, the way I have it hooked up going through the ECU, is not working. What can I do to work-around or get some temporary A/C clutch signal working to re-fill and get the compressor goin', when I want it?

 

[tissimo]

What is it doing? It might not be the ECU at all and might be something else? If you had it hooked up normal and it didn't work with a charge the mkiii A/C Amp controls all the a/c functions and probably something there (with a signal to the amp or the amp itself). The ecu hookup will just mess with the idle really.

I wouldn't hookup the 2j ecu directly to the clutch, as it has no fail safes setup (pressure switches) nor will the A/C Amp communicate with the ecu and tell it when to turn on and off when needed. All my wiring I had was in a thread with the tags 'Wiring Peer Review', I think you started it as well.

 

[Satan]

I switched ECUs and all worked as it should. Problem is, the spare ECU is bad in other ways. Throws codes 22, 27, 31, and 41 (even when you plug it in and haven't started the engine yet... crazy). However, it worked enough to start/run the engine and A/C... However, with the ghost codes and occassional shutting off, I can't trust it to drive to/from work. I am replacing the capacitors to see if that helps, but they've not arrived yet.

I hooked up the ECU this way, after starting the wiring-peer-review thread and may not have updated anything in awhile. Someone else posted the info that I used for the pic above and it worked fine last Summer. Can't remember why I did it. Was it the only/best option, or just a "nice-to-have?" I don't want to do/un-do something that will F something else up.

Funny thing is, I had 5 spare ECUs and lent/gave them away and could really use a known-good one now. Replacing the caps and/or bypassing the ECU is my only option right now.

Bypassing is fine for me, if I can rely on it and it does not cause other issues...