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A/C idle up - Sorted

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Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#805046
I know theres not real many people here running A/C but worth asking, someone may know

My Idle up on A/C request and the A/C relay cut output arent working but I'm pretty sure the problem is in my ECU

it's a Gen 1 D5 ECU and Ive got a blue/red wire that connects to the compressor clutch that signals the engine to rev up on A/C request and also start the rad fan running as well as Blue wire negative output from the ECU for the A/C cut relay not getting any signal from it either
even with or without the load of the relay and the compressor clutch seems to make no difference
Tried swapping them around incase they were labled wrong but no love either

It will all work without it but I'm sure the engine would be alot happier with the Idle up function

Theres an Auto Liberty same as mine about to parted out that I can get the ECU from but before I do that is there anything I may be overlooking?

ian.mezz I never said, I could write or spell

3,913 posts · joined Sep 2004 ·

#805050
ask ratbug 😊
😂🤪😂🤪😂
car forums. where a lot of peoples good intentions end up taking a good old car off the road forever never ever to see the road again. 🥲

ratbug aka toddy101

439 posts · joined Jan 2003 ·

#805065
Sounds like you might have some of the wires mixed up?

I have the red/blue or blue/red wire as the one that goes to the fan relay (year dependent).

The blue wire I have as the cutout relay coil from the ECU. PM me your email address and i'll send you the diagrams.
Does your idle valve work correctly? try unplugging it and see if it changes the revs.
Sharbuilt Beach buggy with Subaru 2L Turbo
Thunderanch Riot with Subaru 2L Turbo
Manxter with FA20turbo
Click here for wiring looms

Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#805126
Cheers Andrew,

Ive tried switching the wires around with no luck and my idle valve is working to perfection ever since i ran the subi upper engine cleaner through it.

The fact that it's not bringing the radiator fan on when it gets A/C request as well as not idling up makes me pretty certain its an ECU fault

It's something I've never tested as the Liberty didnt have enough charge left in it to run the a/c before I dropped the engine

Im gonna take it over to the subi guys and get them to hook up the computer and see if they can pick from that if its a computer problem before i go replacing the ECU

I'm fairly certain it will be fine without it, i have a seperate condensor fan which would be adequate on its own and not many old carbied cars had idle up solenoids

The computer will bring the revs back to 750 once the clutch pulls in, its just that initial rev drop I'm worried about

Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#805172
Gotta Love having freinds in the right places 😎



As I suspected a different ECU and problem gone

Now Idles up and relay cut works as its supposed to.

But you sort one problem, and create another 😂



It's just throwing the purge solenoid valve or circuit code.
Im pretty sure its the pin for it in the ECU plug just not making contact, they were very hard to seperate so I've probbaly dislodged the pin pulling on the wires when I disconnected the old ECU

ratbug aka toddy101

439 posts · joined Jan 2003 ·

#805204
Ahh, do you even have a purge solenoid on the engine, its under the intake manifold, some engines dont have them, so if the ECU think it should it will come up with that... easily fixed by a resistor if you dont have one.
Sharbuilt Beach buggy with Subaru 2L Turbo
Thunderanch Riot with Subaru 2L Turbo
Manxter with FA20turbo
Click here for wiring looms

Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 ·

#805286
Yep, It's still mounted there with the electrical plugged in to keep the computer happy but I dont run a charcoal canister so it's not connected to anything