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

 

[Vladimir]

Grab a power probe or a test light to see if there is a 12v power being sent to the fan clutch. That will be my next step after reading this. Most of the time if the compressor is not used there is a lot of rust buildup between the clutch and compressor pulley, or just the pull in magnet deteriorate and down work no more. If there is no power when the compressor is commanded on, the problem is somewhere in the control side. If there is power, clutch is not engaging and compressor is not kicking on. Give it few love taps maybe any try manually giving power to it afterwards se if it starts clicking. Also connect a manifold to the system, you should have pressure pretty high on the low side without the compressor running. Maybe you got no pressure at all

 

[cswindel]

Yeah you know banging on stuff has worked for me many times. Reminds me of my motorcycle starter haha. Yeah I'll give that a try and see. It seems everything that needs power is getting power so im just lost on if it's electrical or if it is just the compressor being old. Would hate for it to be the compressor because I did just get the system charged like 2 months ago

 

[Vladimir]

If you can spin the compressor clutch by hand and it's not binding, compressor is not seized. As long as the compressor had no open ports in which the dirt and water was constantly falling, it should be alright. I do believe you can just buy a compressor clutch with pulley kit and not change the whole compressor.
But you have to verify that its actually the clutch that's not engaging by testing it.
In theory, when the A/C is commanded on the control unit sends power to the clutch, but it first has to make sure that there is sufficient pressure in the system from the pressure sensor before it engages the clutch. So the pressure sensor/switch acts similarly as neutral safety switch.

Even if your fans are not working properly, your condenser/expansion valve and evaporator is clogged, the system will still temporarily kick on till the pressure sensor tells the control unit to cut power do to high or low pressure.

 

[cswindel]

Okay yeah ill check to see if I can spin the clutch

Is the sensor the one that goes inside the compressor housing or is there another pressure sensor? Because I already jumped the dryer dual pressure switch and that didnt do anything

 

[cswindel]

Theoretically, since I pulled the condenser and a/c lines off when doing the rebuild rendering the whole system de-pressurized and it just got pressurized without the compressor operating, is there a chance that the refrigerant that got load in didnt build sufficient pressure since the system wasnt cycling it? If thats the case, could I force the compressor to engage while the engine is running to move the refrigerant around if it intact does still work? Or is that too much work if i can just easily bypass the pressure switch

 

[Vladimir]

The compressor does not have to be engage for the system to be charged properly. A machine must be hooked up to both low and high side ports to create vacuum. While vacuum is being created all the moisture evaporates from the system. Any reputable shop should monitor the pressure gauges for about 5-10 minutes to see if the vacuum is staying I -30hg without dropping. A drop would indicate that the system is not sealed and there is a leak somewhere ( seals, lines, condenser, dryer, expansion valve, evaporator, etc....). At that point no r134 should be added in the system.

If there is no leak and the system holds perfect vacuum, a tech would add whatever PAG oil the vehicle calls for if necessary (whatever parts were changed) and tell the a/c machine how much r134 to add, based on the vehicle needs. You can see a label under the hood that will tell you the amount. Ounce the system takes all the r134 the pressure get equalized in the a/c system and machine gets disconnected. Tech will start the vehicle and command the a/c to be on. Pressure on the low side would typically decrease to anywhere between 25-50 and the high side would go higher typically anywhere from 150-300 depending on ambient temperature.

Now, let's say you do have normal pressure and your system is full of r134 where it should be. If you decide to bypass all the safety mechanisms, put a toggle switch and give 12v to the clutch the system will work, but not for long as your pressures will go all out of wack, you might freeze the evaporator/expansion blow a line, blow up your compressor and have all the shrapnel contaminate your a/c system where you would have to change every element because they got debris now and will abstract future flow........ To much to list. I don't recommend bypassing and giving constant power. Normal A/C system always cycle, that's why you hear the click and see the room go up.

Get a manifold to check for pressure, or at the very least poke the low side shredder valve to see if r134 comes out under decent pressure.

If you got pressure and the 12v at the clutch when ac is commanded ON. 99% of the time the clutch is at fault and the compressor is changed