aircon issue in ae82 fxgt

[AE25]

im not getting my hopes up.. but maybe some A/C guru can help.

so ive fitted a S/T 20v in an '86 ae82 fxgt (jdm). everything is working except one thing. when i press the A/C button, the aircon compressor engages for 2seconds then turns off. idle raises for this period too. this only happens for one time after the engine has started. i have to stop engine and restart for it to engage a/c clutch again.

There are two things i can think of that may affect this. one is the original bluetop ecu has an a/c wire to it from the a/c amplifier. according to the manual this pin is for the a/c compressor clutch. the wiring diagram shows the a/c amplifier and ecu both connected to the a/c compressor clutch on the same wire. im assuming the a/c amp is engaging the clutch and also giving it an idle up for the two seconds and requiring the ecu to continue giving out 12v? (original 4age ecu not connected) testing this a/c wire from the amplifier shows 12v for the 2 seconds then drops to near zero volts. the ecu a/c pin has nothing connected at the moment.
question is.. does the ecu have any control over the a/c clutch? or is this wire to tell the ecu to change air/fuel ratio or something.

the 2nd possibility is in the ae82 wiring diagram it shows the a/c amp connected to the engine igniter. this i assume is to tell the amp that the engine is running? i'm not sure if this will still be connected or not since im now running the 20v ecu.

it seems the 20v ecu has more to do with the a/c controls since it has a few more pins associated with a/c. im not sure if connecting the ae82 a/c clutch to the 20v ecu will do what it's supposed to.
any help much appreciated.. summer is coming.

and yes i want to keep the aircon! i wouldn't have adapted the original a/c system to the 20v if i had no intention of keeping it.
once i get this last issue sorted i can tape the loom up

[KinLoud]

Hi - possibly related to your problem...
I put a 20v silvertop into a 4afe marino, I left the 4afe a/c pump gassed up and bolted it to the 20v once it was in the engine bay.
The 20v a/c pump has a sensor so the ecu knows the a/c pump is turning. The 4afe a/c pump didn't have this sensor so when I turned the a/c on it would idle up for a couple of seconds then back to low idle and the check engine light came on.
The a/c worked fine, I just had to put up with the engine stalling sometimes due no idle up.

Also - talk to ewan (10k20v) he has just put a link into his 20v fxgt - we did a lot of figuring out how the a/c system actually worked and what the ecu a/c inouts and outputs did.

Ken

[AE25]

yeah sounds like something similar alright. i'm still using ae82 compressor.. it stayed in the car all gassed up and just bolted it to the 20v.
the ae82 a/c seems to run off the a/c amplifier which is a separate controller. there is a single wire on the compressor for the clutch and a two wire plug which i believe to be the rotation sensor. the wiring diagram showed the ce82 as having the sensor.
i could run the a/c clutch on a separate switch but this i believe wont be good for it. if it freezes up or pressure is wrong or idle is too low it'll cause problems.