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Resolved 2G A/C system not working

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cswindel

cswindel

Proven Member
404
590
Jan 13, 2023
Georgia
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
 
Solution
cswindel
A/C is working and this time it was faulty wiring entirely within the OHM harness itself (no OHM to OEM connector/pin mix ups like the last 2 issues).

Basically the white wire in the dual pressure switch as pictured:
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Is part of their under fender connector circuit on the driver side (where the OEM one is) and, from all the testing I've done and bouncing it off the OHM "engineer", the wire from the dual pressure switch that goes into the connector as pictured (all the colorful wire one):
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Was not pinned right such that the receiving end of that connector was not making contact. So basically the wires that were supposed to meet in this connector to form the halfway point in the circuit didnt meet up (so much...
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Add a little bit of PAG, I'm sure you had the system open for a long time. Monitor the pressures according to ambient charts... But I would for sure change the condenser seals, receiver/dryer and the expansion valve... It's all cheap stuff.... Vacuum the system, let it sit for 10-15minutes, make sure the needle is not dropping...if all good add PAG and whatever amount of r134 the system calls for ...

Or just add whatever is missing and see what it does...if system is restricted and have problems, go to a shop and recover all R134, so you don't poison the environment....birds need to fly, and penguins need to lay eggs or something...
 
Upvote0
Vladimir said:
Add a little bit of PAG, I'm sure you had the system open for a long time. Monitor the pressures according to ambient charts... But I would for sure change the condenser seals, receiver/dryer and the expansion valve... It's all cheap stuff.... Vacuum the system, let it sit for 10-15minutes, make sure the needle is not dropping...if all good add PAG and whatever amount of r134 the system calls for ...

Or just add whatever is missing and see what it does...if system is restricted and have problems, go to a shop and recover all R134, so you don't poison the environment....birds need to fly, and penguins need to lay eggs or something...
Click to expand...
Do you have those charts by chance? Also thank you again for all the help
 
Upvote0
Alright now something weird happened. I was running the car to finish the charging. Got it to 55psi and it sat there for a few minutes with the HI side reading about 325. After some time making sure it would stabilize the pressure on both sides crept up and once it got to about like 80 psi or so on the LO the compressor started clicking on and off. The a/c fan never kicked on so im thinking that might be the problem? Since it never kicked on to cool the refrigerant it got hot and built pressure
 
Upvote0
You still have issue with ohm wiring. That's why I asked about condenser fan so many times.I'll highlight it when I get a chance. If the condenser fan doesn't kick on pressure will climb, temp will go up. Dual press switch will kill the system. So will the temp switch.

You can for now just jump constant power to the fan. But I'll highlight the diagram for you a little later today
 
Upvote0
Ok. I remember at the very beginning you said that you see both fans kick on, once your engine reaches operating temperature. This is a good thing, it means that OHM wiring is all correct there. If that is the case and they both fans kick in, It also tells us that PIN 30 of the relay in question gets 12v and the 20 amp fuse is not blown. It also tells us that the ground that goes to the condenser motor and PIN 85 should be good. But I still highlighted them in red, because it takes only a minute to verify with you power probe.

Here some diagrams. Everything that I've highlighted in red must be checked and verified. You can jump 30 to 87 to see if the condenser fan kicks on, or just give pin 87 12v with the probe, the fan should turn on right away. If it doesn't there might be an issue with the motor or the circuit going to the motor ( corroded connector/ broken wire etc....). I say this scenario is very unlikely....but like I said it takes a second to check.

Here is what I really think is the actual problem, and it again goes to you favorite dual pressure switch. Since we know that OHM messed up both sides of the wiring (to black box and connector A-32) from the press switch, there is a very big chance that they never spliced in the trigger wire going to PIN 86. That is the original G-O wire, that is now from what I remember is Gray.. you have to do a continuity test between that wire to PIN 86 of the condenser fan relay. If the circuit is not there, the condenser fan motor will never get triggered by the A/C system itself. However! The condenser fan will still work once the cooling fan turns on, because it operates in conjunction with the cooling fan, but only when the engine gets hot. And again I'm going based of what you told me before, that you've seen both fans turn ON at the same time...

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The only pins I got continuity with for the a/c fan connector are the blue and orange wires as depicted:
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These both were continuous with pin 87 of the relay. The other 2 wires are black and did not have continuity with the relay on any pin.

The gray and white wire for dual pressure switch do not have continuity at any of the relay pins
 

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There are 2 condenser fan relays, make sure you are testing the right one. Two black wires are a chassis ground, but they also must go to pin 85 of the relay, without pin 85 being grounded the relay will not energize.

Use your probe to verify you got 12v at pin 30 of the relay. If yes, put a jumper wire or a clip between pin 30 and 87, the fan should turn on. That would verify that that part of the circuit is working.

Also touch pin 85 with your probe. Does it beep for ground?

From what you are saying it sounds like OHM didn't route pin 86 (trigger wire) from dual pressure switch to relay. The black wires are ground and they must bring that ground to pin 85. Looks like the wiring is not routed there properly as well.

Jump 30-87 and lmk what happened
 
Upvote0
Connect the probe to the battery, ignition doesn't have to be on to verify-
pin 30(12v)
Pin-85 (grnd)

Just touch the tip of the probe to the pins. It will display voltage and beep.

Or it will display ground and beep differently

You can also give 12v with the probe to PIN 87 instead of jumping wire from 30 if you want.
 
Upvote0
Ok. If those 2 wire go to 87 they can not be ground. I believe something is not right with the way things got tested. I'll draw out a diagram on what's the problem is. You are missing pin 85 ground and pin 86 12v from the pressure switch. It's an easy fix, but instead of splicing wires you can show the diagram to OHM and ask them how they want to rewire it for you, just like they did last time.

Also you never confirmed if you jumped power with a paperclip or booster wire from 30 to 87....you didn't attempt that right?
 
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Yeah but for some reason OHM doesn't like the FSM wirimg diagrams because they have their own way of wiring things but as much as I ask they never send me their schematics. Hopefully they will send it tomorrow.

I didn't jump power because I didn't know if since 87 is a ground if it would mess something up
 
Upvote0
If it is truly a ground it will blow condenser fuse. Here is what we got. You can send it to them. I did notice that the wiring is different from what the actual schematics should be, when you told me both wires go to pin 87, there should be 2 pins 2relays, bet regardless it's should still work once the two points I've highlighted in red are fixed.
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In my opinion it's a pretty evil thing to do. Change all the wiring color, route power and grounds through different points, way different from the factory schematic. Get some wires mixed up and tell the owner we don't have schematics for you. Just keep fixing our mistakes by guessing what we put where .... That's not really a good business in my opinion. Also charging crazy money for a harness, I'm sure it costs close to $2k, that's a good chunk of change

Maybe it's not common for them to make mistakes. But at least they answer and try to help
 
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Yeah its whatever at this point. And yeah they do rectify things after a lot of back and forth with hit or miss communication. I just gave up with them and come here to find the problems, then I let them know and hope they fix it without needing to rip the harness out, send it to them and then re-install it.

And I'm in way deeper than just $2k haha (dying on the inside)
 
Upvote0
Well . There is not much to test with this condenser fan. It's not a complex circuit at all, compare to what we went through before. I just don't want you to start spicing in your own wires and jumping them to the two missing pins on that relay. Im sure once you tell OHM what we found they gonna know exactly what got wires wrong and how to reroute the pins without cutting wires.

There is one thing tho that we can do while you wait for them...we can make the fan run all the time by giving it power by jumping it through the relay. This way you can run the car and if there is no restrictions in the a/c system, the pressures are gonna be under control and dual pressure switch won't shut the a/c off... But for that to we need to verify why you say there is ground at pin 87 with the 2 colored wires from condenser fan going there. That's not right
 
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Back probe with a multimeter the four pin connector at the condenser fan while it's still connected. Only the two black wire should have continuity to chassis ground. The two other wires shouldnt. Verify that....if they do it's the ground pathing through the motor windings and it will not short anything out once we jump power to energize the motor. As long as blue and orange go to pin 87, we should be safe. Worst case scenario is a blown 20 amp fuse...but I really don't think the motor is shorted out, cause you told me you've seen both fans kick on before


If that is the case you'll use a jumper wire for the relay when ,,,a,/c is ON, and it won't affect anything else in the system. You would just have to pop the hood and disconnect it, every time you park until ohm gives solution
 
Last edited:
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I just want to note that helping digitally through a forum is more than what OHM who sold the product will ever do. Thank you @Vladimir for being on this forum with your knowledge and experience for the love of the game and figuring out issues.
 
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