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Author Topic: Idle air control signal, turbo swap, a/c  (Read 1336 times)

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Offline denmach1

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Idle air control signal, turbo swap, a/c
« on: August 18, 2014, 05:36:59 PM »
I am in the middle of a turbo swap into my 77 Cruisin Wagon using a LA2 ecu. I am also installing a vintage air system. Does anyone know what type of signal I need to send to the ecu to adjust the idling when the compressor turns on? (voltage? ohms? which pin? etc...) Any help is greatly appreciated.

Offline Wittsend

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Re: Idle air control signal, turbo swap, a/c
« Reply #1 on: August 18, 2014, 06:58:49 PM »
As best I can recall an LA-2 and and LA-3 are direct swap ECU's. My Pin Out for an LA-3 shows:

 10 = A/C clutch - A/C input

54 = WAC  WOT (wide open throttle) A/C cutoff

There were also two fan control signals one of which might be relevant to the A/C:

52 = HEDF Highspeed Electro-Drive Fan

55 = EDF    Electro-Drive Fan (low speed)

Hope this helps. At the moment I don't have the "type" of signal sent only where they are going/coming from. Are you using the factory relay box?

Offline denmach1

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Re: Idle air control signal, turbo swap, a/c
« Reply #2 on: August 18, 2014, 07:11:54 PM »
Wittsend, thanks. I am using a Vintage air system and its controls. I see the a/c input on pin 10 of my diagram but just not sure what kind of signal to send to it. I can easily send 12v to it when the clutch is engaged but i need confirmation that that is what it needs. I don't want to fry anything

Offline oldkayaker

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Re: Idle air control signal, turbo swap, a/c
« Reply #3 on: August 19, 2014, 12:44:42 PM »
The 87TC EVTM shows the LA2 pin #10 connected to the +12V side of the A/C clutch coil.  Note there is one of those surge protection diodes in the wiring harness connected across the A/C clutch coil to moderate the voltage spikes.  I believe this #10 pin is the circuit that opens the IAC a little to maintain idle speed when the A/C is on.
Jerry J - Jupiter, Florida

Offline denmach1

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Re: Idle air control signal, turbo swap, a/c
« Reply #4 on: August 19, 2014, 08:10:40 PM »
Thanks for all of the great info guys! This build would be a real struggle without this site and all of your knowledge and help.