4g61t.org

Alright, I've searched and there is no real usable information on the wiring side of getting A/C to work with a swap. I've now spent at least 4 hours just going over what needs to be wired where and I'm still pretty lost.

All I've got so far is this =

*C-58 (DSM connector) - pin 12 - green/white - goes to *C-19 (csm) - pin 15 - green .
That is the connection for the AC control module.

*C-17 (csm) - pin 1 - yellow/green - goes to C-19 (csm) - pin 1 - black/yellow .
That bypasses the refrigerant temp sensor in the compressor which doesn't exist on a DSM. This is just a theory right now, I don't know if this will cause issues by not connecting that sensor.


I'm still trying to figure out how to get the dual pressure switch wires up correctly. Can anyone who's connected AC help me out here? I'm planning on doing a full write-up on the wiring for a swap with AC when I'm done.

What harness are you using engine bay side for the ECU, and for the engine bay (AC,radiator fans, alternator, etc).

Do you have the AC relay box that plugs in just beside the power steering fluid reservoir/left front corner?

Which compressor is being used?

I believe a 4g15 compressor can be used with a clutch pulley being the only part needed to be cross over to match belts/pulley scenarios.
4g61 compressors already have the proper 4 rib pulley installed, just like the Galant/DSM.

I am using a 91-94 DSM engine harness which has three wire that go to AC. Two wires to the dual pressure switch and one wire to the compressor clutch. The engine bay wiring (lights, fuses, etc) are all csm factory.

I have all the factory AC wiring stuff, including the relay/fuse box on the front driver's side.

I have all the actual hard part stuff figured out, what pulleys, bracket, compressor, etc to use. I have a galant bracket, tensioner, factory compressor with correct pulley.

I'm just trying to figure out where and what to splice on the engine side to the factory AC stuff and on the under dash area. I know there have been a couple guys in here that have swapped and kept AC.

I even watched lilevo's videos but they don't go into the specific wiring for AC, just general and it more covers how to install and fill it.

I'll post some pictures for reference sake, as not everyone has the manual at hand.
Fan-out sheet for AC system on 89 Turbo/Non-turbo, other years (1990-92 USDM )should be the same with only minor wire color changes I suspect.

So, essentially you need to melt the Galant/DSM style compressor connections with appropriate wiring on the CSM side of the car.

I am hoping that all components from this era can talk to the Auto-AC units that are buried in the dash, as you will see in the pics to follow, and not have issues electrically - switches are switches, sensing components are all the same resistances, etc.

Pictures of 1989 Mitsubishi Mirage Turbo/NA AC wiring for swapping between DSM/Galant components and Colt Mirage Summit.

Component locations are shown, as well as connector locations.

IF you are wiring to the dual pressure switch, it is essentially a break/connection in between the compressor clutch relay (high current side) and the wires that lead from the 12V positive side coming from the Auto Compressor control unit.
There are shown to be one wire that splices into the 12V positive feed just before it reaches the dual pressure switch and that is a 12V low/trigger signal to the condenser fan motor relay.
IF at any point the pressure switch goes low or high from it's set points, it will break the feeds for the compressor clutch relay and the condenser fan relay.

I see where you are tapping into CSM ECU pin 15 for grounding of the low side signal for the compressor clutch relay.
Your CSM control equipment does not have control using a feed from a temp sensor as a backup to again, cut power to the compressor clutch and a condenser fan.
So, basically bypass that function on the compressor.
Leave the switch installed, maybe find a connector somewhere to cut short and plug it off with for cleanliness should you ever need to go back to it ...
Don't worry about the switch essentially.

All you need to do is mimic the CSM control functions.

Compressor clutch relay and condenser fan relay feeds get cut by the dual pressure switch.
Match up power feeds and ground sides to/from each unit; Auto Compressor Control Unit and the ECU.

Let me know if I have missed anything here, and I will see what I can do.
Feel free to use anything posted here with your write-up, or we can simply add things here and go from there with regards to edits for the title and such.

I can always break the thread in two and split anything posted past a certain point, and rename it as a separate thread. It would contain all relevant info until then, in one place.

Alright, did some more digging, staring at wiring diagrams and trying to picture everything in my head so that it makes sense! After a couple more hours, this is what I've come up with.

I have the under dash wiring correct.

The csm harness is actually quite awesome as it makes life very easy as far as wiring goes, just a little confusing.

On the engine bay side of the wiring, I need to do the following.

* DSM connector A-08 - pin 2 - GW - needs to be cut and connected to CSM connector A-22 -pin 6 - G. This is the dual pressure connector from DSM going to the 6 pin connector from the CSM engine harness. (I'll add pictures later)

* CSM connector A-22 - pin 2 -BW- and 3 -GY- need to be grounded. They originally go to the ECU which then grounds but there is no way (aside from running two wires or reassigning two wires) to get them back to the ECU. This should be a non issue, the ECU will simply not raise RPMs when you turn on AC.

That will make all the connections the stock wiring requires and should give you a working AC system.

I do not claim to be a wiring genius or even good at it, so if this doesn't seem correct, let me know.

I went through all this a few years ago when I swapped my colt. Sadly I didn't keep up with it but I do remember going to bed a few nights with a headache .

I do know that the csm's compressor has a refrigerant temp sensor that has to be wired to the dsm engine harness since the dsm doesn't use this on it's compressor.

_________________
93 Mitsubishi Expo LRV 1.8/manual
95 Eagle Summit DL Coupe 1.5/manual
01 Mitsubishi Mirage ES Sedan 1.8/manual

I've done some google'ing and searching with no results, does anyone know what the ecu does with the signals it gets for the relay? I know it allows the connection to ground so that the relay activates but I don't really know why the ecu has any play in this. I remember reading something about the idle being raised when a/c is activated but I can't find anything on it now. Possibly to cut off a/c under full throttle?

The ECU doesnt cut the AC on full throttle.

The AC ECU's go bad a lot and I don't know why. I've replaced every component in that thing without luck. I've also chased problems around forever when the issue was that stupid black AC ecu.

It's been awhile and I think I got so fed up that I just wired the A/C compressor right to the AC switch on the dash and bypassed the black AC ECU. Econ AC switch on the dash doesn't do anything anymore. I now have the AEM EMS Series 2 setup so it does A/C control, idle control, and cuts the AC on a certain throttle input percent.

OK, that's good to know about the AC ECU's going bad. Thanks for responding to the thread, I know you are probably the most knowledgeable with these cars and the swaps.