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Discussion Starter #1
I'm running standalone ECU and cant get aircon on my 1994car to engage, i bypassed frost and pressure switches, and its only missing input that engine is running on 3 wire plug that goes to ECU, its under wipers.

Pictures link here
I had it hooked up like this on my old car and i forgot what wire it was, and does it need to connect to GND or +12V .
I think it was to +12V becouse i had fuse on wire.

Pictures link here
 

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Lost I am lost on what you are doing here!
 

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Discussion Starter #4
So if i have only one side of this G337 connector, becouse i dont have engine ecu or loom. what can i bridge to get AC going?
Should there be RPM limit or acceleration limit to save AC compressor.
 

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Do you have R134a in system? OK here is what I see, just hook all the wires back up to Q20 trinary switch and Q26 frost switch. Now go to G337 connector Pin A black wire and connect/jumper it to Pin C gray-yellow wire in that same G337 connector to energize Q22 A/C compressor clutch relay when you push A/C button on Q66a A/C dash panel. Pin B Brown/Green goes to A/C panel Q66A on dash so Pin B should be OK as is so don't hook anything to it. Report your results. As you know the earlier 164s don't have a G337 connector.
 

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Discussion Starter #7
No, system is empty, i have to be able to turn compressor on so shop can properly fill r134a.
SO my 1994 Super 24v should work with bridging A and C wires, i will try and report.
at g337, male side connector at AC side, I have green #1 wire, and yellow grey #3 wire middle is brown-green like i posted in link.

Thanks for help.
Its heat wave here here and im driving my 3yo doughter so i need A/C...
I have new dryer, new front condenser, pag oil, diy compressor mounts on 24v engine and compressor clutch is tested, new green o-ring everywhere, i hope it will work.
 

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#2 B wire should not need anything as it goes to A/C dash panel.
 

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Discussion Starter #9 (Edited)
i tryed to brigde #1 yel-grey and #3green wire and it wont engage clutch with AC set to auto and low temp set.

I measure 12v on green wire pin1 with everything disconnected.
I found my old harness and i had only pin1 green wire connected to small 3A fuse, i'm not sure if it was to + or GND.
EDIT: i got continuity betweeen #2 and #3
 

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OK, try this ground G337 pin A/1 green wire which is in Euro wiring but in my wiring book is Nero/black to chassis. With key on relay should click and compressor clutch should engage.

If that doesn't work go directly to wire connector at compressor and apply 12v to see if clutch coil will engage clutch.
 

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Discussion Starter #11
I got solid +12v on that g337 #1 green wire with key on, its not 10V, where that wire goes, i dont want to fry dashboar aircon controls....
 

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Discussion Starter #12
when i connect #1 to gnd it engages clutch, as soon key is turned on, ON/OFF aircont does not affect, and then i removed frost switch and red connector bridge and connected everything back to stock without gas in system and it still engages clutch when gnd is supplied to #1 green. On other super car with same ac control unit it worked, i cold press ECON to turn off compressor, if i left it on auto it would engage it, even without engine running, becouse there was no engone ecu, and becouse of bypass, any ideas how i could do this, i tryed to bridge 1 and 3 with trynary and frost bypass and it didnt worked
 

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Do you have Euro 164 wiring diagrams? Automatic Heater/Ventatlation System wiring Sec.4-2 and Sec 4-3 Looks like jumpering 1 and 2 might do it as 2 goes to a/c panel which may go to auto/econ buttons and leave pin 3 disconnected.
 

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Discussion Starter #14 (Edited)
Thank you for diagram. i taped three pages together,.for 24v it should be Q61A **per note on bottom for motronic m1.7 " it says that Q61A is used and its joint for motor control unit and MSA6.
Don't know what MSA6 is :)


Its strange that grounding green A wire energizes relay, because trinary switch is open (checked). Thats my main problem.


il quote E.T. user from other thread:

"As I planned, I started the engine and then jumped grey/black and brown/green wires at red connector by trinary switch. As I cycled the econ button on and off I heard the relay finally click.

I think it works like that : After switching a/c on, a/c panel sends +12v to Engine ECU .The same current splits into the grey/black wire and goes to trinary switch pin1. If pressure ok, it sends current further to frost switch which,if no frost on pipes, sends it to ECU ( frost/sw->grey yellow->g337 pin C -> pin 85 of ECU.

The engine ECU is the only possible source of ground which has to be applied to pin 85 of A/C Q22 relay to finaly energise compressor. Once ECU gets +12 directly from A/C panel through brown green wire at ECU pin B, it waits for +12 which comes from this additional circuit consisting of trinary switch and frost switch to ECU pin 85-this happens when proper pressure and frost conditions are met. Only then - with +12 on pins 85 and 86 of ECU ,somehow inside the ground is applied to its pin 48 straight to pin 85 of Q22 relay which energises compressor. Applying ground to grey/black wire will do no good- it will only close circuit of A/C panel feeding +12v, but will not cause the engine ECU to apply ground to Q22 relay. There is one more essential condition: the engine has to be running, otherwise ECU will not apply try to energise compressor clutch,simply because it "knows" there is no such need.

I think in earlier models engine ECU didn't decide on anything, it only got informed about A/C beeing turned on through pin 87a of Q22 relay to increase idle, this is why it was possible to aply ground to the wires to check for relay clicking. "
 

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24v M1.7, 12v turbo ML4 so MSA6 is diesel model.
1637024
 

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Discussion Starter #16

I solved the problem, on this euro super 24v car with m1. 7 motronic taken out i needed to ground green wire to directly engage cluttch regardless of trinary switch or console button. when trinary is working it sends positive 12V on gry_yel and when ac is turned on it sends positive 12v on middle B wire, that two 12v wires turns on two relays who passes ground taken from chassis to green compressor wire. if ac button is off it wont work, if its on and trinary is off it wont engage...

now i can refill r134a and use aircon with standalone ecu.

Only AC and EVAP dont work after taking original loom out....
 

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Are you cooling now?
 
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