Resolved 2G A/C system not working

[cswindel]

Alright electrical nerds I need to be graced with you assistance as I am no good with electrical.

Current situation:
- A/C is not blowing cold air although the system has been charged recently without the system actually pulling in r-134 because well it dont work haha
- I dont have any prior knowledge of whether it worked or not before or after my teardown of the car
- As a side note I am running OHM harnesses throughout the engine bay and interior and running ECMLink v3

Current untested areas and possible theories:
- A/C compressor is dead and I have not ran 12v power to it such that I can test if the clutch engages or not
- Seeing if there is a setting in ECMLink that I am missing since the a/c and rad fan both kick on when signal for rad fan to kick on gets pushed out
- Thermo sensor is poop but havent checked and the wiring diagrams confuse me on where it is physically located behind the glove box and there arent really any pictures when i look.
- ACCU is poop but havent checked and not sure which wires in the connector to check but havent dug into that area yet because its a pain to reach

Steps I have taken thus far:
- Checked continuity from ECU pin 22 to A/C compressor relay in fuse box (Good continuity)
- With key in ON position and engine not running, I have voltage going to the a/c fan (connector A-39), Dual pressure switch (A-47), and the A/C compressor (A-95)
- With the engine running I checked for voltage at the same connectors and nothing concerning
- With the engine running and a/c switch active I checked voltage again and still nothing concerning. A/C compressor ground showed grounding too.
- With the engine running, I jumped/bypassed the dual pressure switch and no result came about from that
- As mentioned prior, I noticed that the a/c fan and rad fan kicked on at the same time when the signal for the rad fan got passed through the circuit (I dont know if this is normal or not but hey 2 fans is better than 1).

Just wanting to see what your inputs are with this matter before I start going down unnecessary rabbit holes without much guidance (because I will get lost, sad, and confused and it might all occur simultaneously). I believe I have covered the majority of what I have done and assessed to get this thread rolling at least

 

[pauleyman]

I gotta ask, fan was on?

 

[cswindel]

I gotta ask, fan was on?

No the fan never kicked on and I mentioned that to Ohm when I was talking to them but they never said anything about it. Only time I've seen the a/c fan come on is when the rad fan kicks on to cool the rad

 

[pauleyman]

No the fan never kicked on and I mentioned that to Ohm when I was talking to them but they never said anything about it. Only time I've seen the a/c fan come on is when the rad fan kicks on to cool the rad

I mean the fan switc in the car. If switch is off ac is off also

 

[cswindel]

I mean the fan switc in the car. If switch is off ac is off also

Oh yes yes the fan and blower motor operate just fine. The knob and fan have always worked on the car that I do know

 

[Vladimir]

Ok I ask my brother to log in at home. I would look the diagrams tonight around 2am but meanwhile here for you

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Supposedly this is automatic controls

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[Vladimir]

This is manual control

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I haven't check any diagrams yet but maybe you can start or examine them. We can go from here now later.

 

[Vladimir]

Ok. So the system might be a little bit more complicated. I'm not sure why all the diagrams are getting downloaded like crap with horrible resolution, but I'm gonna try to attach another set in this post.

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The first thing that we should probably establish is if in fact your model DSM has two different control modules for the A/C system. I have circled the module that should be located in yellow. Verify please that your vehicle does in fact have this module. It should be in the glove box next to blower motor and it should look like the one on the picture attached .

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[cswindel]

Sure do! Dont know if the silver box one is relevant but while I was under there I grabbed a Pic of it too

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[Vladimir]

Ok. Great.

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Looks like the ECU provides both power and ground to the A/C clutch relay. . you have been at that relay already. We have to establish if there is any changes at pin 1,3 of that relay when you turn A/C ON. Give me before and after.

Go to your pressure switch under the hood, pin 1 green/ red line wire. What do you get at the pin with a/c ON and OFF. Also check for continuity between pin 3 of the relay to pin 1 of press switch. They are spliced together.

Lastly check Pins 38 and 64 coming out of your ECU if you never gotten any changes, they are harder to get to, and should not be necessary if there is power and ground changes at the previous test points we would know that there is no opens and continuity between the ECU control and a/c relay + press switch.

Pin 38 of ECU, pin. 1 of press switch and pin 3 on relay should all be continuous.
Pin 64 ECU pin 1 A/C relay should also have continuity . They are the power and ground controls from ECU.

Some simple test should take more than 5-10 min we can start there

 

[cswindel]

Is pin 1 and 3 of ac relay pin 30 and 85 respectively? Also is pin 1 of pressure switch the signal wire? Ohm racing doesn't color code wires the same as OEM

If thats the case with pin 30 being the pin 1 which is constant power and pin 85 being pin 3 and I sticking the red probe in 30 to check for 12v then verifying 85 is ground or am I using the multimeter on both pin locations simultaneously? I guess im wondering how to check for changes if they are in fact constants (if I have the pin relations right)

Also I can verify that the dual pressure switch is getting power to it, I have checked that off before

 

[Vladimir]

No, you got the pins wrong, but it doesn't matter. Let's abort this stage. And start even simpler. I am not really familiar with ohm racing harnesses, I do know that they can be heavily modified and many components can be bypassed. They mostly concentrate on engine performance and tuning. )ETA go to the roots.

When you ordered the harness did you request A/C function to be left alone and unmodified?

How many connectors of that harness go to your ECU?

Do you have a factory ECU or some aftermarket standalone unit?

 

[cswindel]

No, you got the pins wrong, but it doesn't matter. Let's abort this stage. And start even simpler. I am not really familiar with ohm racing harnesses, I do know that they can be heavily modified and many components can be bypassed. They mostly concentrate on engine performance and tuning. )ETA go to the roots.

When you ordered the harness did you request A/C function to be left alone and unmodified?

How many connectors of that harness go to your ECU?

Do you have a factory ECU or some aftermarket standalone unit?

Yeah so when I ordered the harness I asked to retain a/c function and it came with all the connectors (as far as I know at least)

Im not exactly sure but a/c fan, a/c dryer, the engine relay box, a/c compressor are the connectors that are part of the harness that hook up to the components as far as I can remember

Im running stock ECU with ECMLink V3

 

[Vladimir]

Ok. I'm sure that there is gonna be a problem with the wiring controls just because your condenser fan is not kicking ON and you say that there is actual power being present at the connector for the press switch. With a/c ON as far as you know.

So, here is where a lot of this older diagrams get confusing. I do believe the way that they are showing how everything should be connected is correct but the pin out labels might be different. To make it less confusing let's start with this.

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This is the pin out diagrams for the ecu. It labels all the pins different than the diagrams we have for the circuit. I do believe this pinout diagram to be correct.

Find pins 22, 42 and 45 they are all responsible for the a/c circuit. Do you have wire coming out of those pins going into the harness?

That will verify that indeed the A/C function was intended to remain on the vehicle.

Note: I mentioned about the condenser fan with the assumption that you duel pressure switch is completely functional and your system got adequate pressure, it is not a fact that it actually does work. But we can get to that later if necessary.

Also here is a simple theory of operation onto what is happening . When you hit the a/c button power gets sent to the Auto air conditioner ECMtunning (black box) power comes out of the black box and goes towards the pressure switch and into the condenser fan relay. Ones the pressure switch has pressure it closes the circuit and sends power to the a/c compressor relay and also to the ECU. ECU sees the power and gives ground to the a/c compressor relay and the relay makes circuit sending power to the clutch. This is what it most likely looks like according to all diagrams I just want you to see it same way. I can highlight the diagrams for you. If you want? Also take the plug of from the press switch and touch the two pins the should be continuous with zero to no resistance since we have pressure in the system. Lmk

 

[cswindel]

Well it looks like they did some weird stuff again and left out a wire for pin 42 but I have 22 and 45 with 45 having 2 wires. 22 does have continuity with the relay

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Im reading 0.04 ohms on the pressure switch itself

 

[Vladimir]

Good. Almost zero resistance indicates that the pressure switch made circuit. It sees the pressure and work as intended.

We will continue. Just give me some time. I'm doing gigs again

Also if pin 42 wire is missing the a/c clutch will never get triggered, because that pin according to the diagram goes to intermediate pressure switch, which is probably another stupid way of saying dual pressure switch. Please verify that indeed 42 is missing

 

[cswindel]

Yeah there is no pin 42...the more I have troubles with this harness the more I hate how much money I spent

 

[Vladimir]

Ok, great. We might have located the main issue. Please don't try to hardwire anything in yet, we will do more testing because there is so many variables that are still unknown. I'll get back

 

[Vladimir]

This is my theory. Since all the colors of wires are wrong, because the harness has changed, and all the pins on the diagrams have different numbers only thing we can assume is this, pins 22, 42, and 45 are as followed.

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What we can do next is check the power coming out of the automatic a/c controller (black box). The wire that I've highlighted in yellow.

You mentioned before that you have 12 volts available at the dual pressure switch connector. We have to verify at which pin is the voltage present and verify the source that actually sent that voltage there.

Disconnect the connector from dual pressure switch. With the ignition on or the car running, command the A/c to be ON. With a power probe or your voltmeter verify which one of the 2 pins gets 12v. It should only be one wire.

Once you verified the wire, turn off ignition and trace the wire back to its source(Continuity test). It should be going to the little black box that is under the glove box. There is a possibility that the wire color might be green/orange at the black box connector since I doubt OHM racing harness extended all the way to there.

Tell me if the power is confirmed to be coming out of the black box, going to one of the two pins on press switch.

Also do you have anyone on here or any friends with a 2nd gen that can verify that their ECU has pin 42 going to one of the pins on the pins on the dual press switch connector?

 

[cswindel]

This is the pin for the dryer pressure switch connector that is getting any type of voltage but its random low value spurts. No constant voltage

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There is no continuity on the black box connector to dual pressure switch. I checked every wire combination between the dual pressure switch connector and both black box connectors

I think the only time I got a good voltage read off the dual pressure switch connector was when I forced on the compressor but I can't remember. Too much electrical stuff for me to remember clearly haha

 

[Vladimir]

Inconsistent spikes and no constant voltage? On that one pin for press switch? How high did the voltage get? And that one pin that was doing it, could not be traced back to the black box, correct?

Check if there is any continuity from either one of the pins on the press switch to pin 45 on ecu (the one with 2 wires coming out of it).

 

[cswindel]

No continuity and it was a super low very brief voltage. Maybe 0.5v at best but could have been a multimeter false read

 

[Vladimir]

So briefly, neither of the pins on the press switch got any continuity with pin 45 on the ECU and any of the pins on the black box, correct?

The only continuity you got is between pin 22 and one of the pins of the compressor relay? Correct?

 

[cswindel]

Yeah that sounds right

 

[Vladimir]

Ok. Since you are missing pin 42 to relay, there is no continuity on any of the pins from the pressure switch to black box and ECU and you only have pin 22 of the ECU going to the relay, and you did all the testing correctly as I described, it can only mean one thing. Here is the diagram:

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This diagram shows that both of the circuits from your black box and ECU (except pin 22) are missing and not going to the pressure switch.

By jumping power to the clutch you would also give power to the dual press switch. If you jumped power from the trigger pin. That would explain why at that time you got 12 volts at the pressure switch .

By missing or that part of the circuit being incorrectly routed that will explain why you never got the condenser fan to kick on when you bridged/jumped the pressure switch pins while the A/c was commanded to be on.

Do you have a way of getting in touch with OHM racing, maybe they safe blueprints of how your wiring is customized, because right now it's looking like the a/c option is incomplete.

There is a way you can fix all of it properly but it's very difficult to explain and requires at least a decent knowledge of how to wire thing, you have to be able to fully read and understand the diagrams I sent you, plus you are dealing with inputs going through ECU, if you miswire stuff you might damage it.

There is also another way to fully make this system independent, by buying two 4 pin relays and a toggle switch, two fuses and some wiring, we can leave the dual press switch as a safety device and it will be our gate keeper for the clutch to shut off/cycle and act as a safety device. It will probably cost you all under $60. I can draw out a diagram and explain how to wire it independently instead of fully getting rid of A/c permanently. There will be minor down sides, rpm will not go up when clutch kicks and evaporator might be getting iced up before pressures change enough to cut power to clutch.
That will probably be the easiest way, and least electrical knowledge required way. But even that doesn't guarantee that your system is not internally clogged/restricted, because we know that your low side pressure was acting like there was a clog in the system.

Lmk

 

[cswindel]

Oh geez this is terrible. Ill see if they will answer but dont hold your breath. Is it primarily because pin 42 was never routed?