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

 

[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

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

 

[cswindel]

I just checked the clutch and it spins nicely but that still doesn't rule out the magnetic failure being a possibility. But for that I could send 12v to the pin as a dry test to see

I tested the signal wire on the compressor for ohms and it read 114. That seems pretty steep for resistance

Alright so I went ahead and sent 12v to the clutch. I did 3 pulses and on all 3 the compressor clutch engaged. Ill have to run the car again I guess and re-verify the voltage readings I got to make sure that there is in fact 12v going to the signal wire from the harness side

Could it be a pressure switch still?

 

[Vladimir]

There should not be 114 ohms resistance at the clutch wire. That high resistance would indicate that either there is corrosion in the wire connectors or loose connectors. Or depends how you tested it. If you tested the control wire coming out of the ECU that wire will go through the pressure switch, temp switch and the relay before it gets to the clutch. Check everything in between. It's good that the clutch is working. Your problem right now is in the control side

And do make sure that there is enough pressure in the system. Pressure switch will not make circuit without proper pressure, for the clutch to kick

 

[cswindel]

Just want to say thank you for your time on this and all the help!

Okay just so that I dont get a false hope haha, let's say i run the car and there is 12v being pushed from the harness side to the signal pin on the ac compressor for the clutch when I meter it. Would that then just isolate it to the compressor wires or could I still get that 12v and nothing happens

Also when you say pressure switch do you mean the dual pressure switch on the ac dryer? Thats the only pressure switch I've jumped or you mean there is a pressure switch internal to the compressor itself?

When the shop charged the system I believe they only pushed 40-50 psi if I remember correctly. Would that be too low?

Also could you help point me in the right area of behind the glove box where the thermo sensor is? I generally understand but haven't seen a picture of where its actually located and wire diagram stuff kinda gets me there but still uncertain.

Haven't tested the accu yet either due to not being sure of what pins to test for what

 

[Vladimir]

If the a/c clutch pin gets 12v and it doesn't engage the compressor (no click) the clutch should be replaced or the whole a/c compressor because it's extremely difficult to find replacement clutches.

We are talking about the same pressure switch next to the dryer, yes.

I'm not sure on what the shop did. They were supposed vacuum the system and put whatever the required amount is. If the shop just pulled vacuum and they noticed the needle dropping, they probably aborted the whole operation because the system is not sealed (leaks at seals etc...) There is actually no way to set up PSI on the A/C charging machine, it goes by volume of gas only, and psi pressure results from the amount of r134 that goes inside the system. The pressure is always different because it is dependent on ambient temperature and compressor output when it is engaged. If there is abstractions the pressure changes as well.

I seriously doubt your system was sealed if you didn't change the O-rings with proper new ones when you removed the condenser. One the first thing you should do to begin diagnosing A/C problems is to connect a manifold and check pressures. IF there is no r134 or insufficient press, dual press switch will not close circuit for the relay to energize and open power to the clutch .

I am not sure exactly where the thermo sensor sits. It should either be on the evaporator fins with a pigtail extending through the HVAC unit near glove box, or maybe around the intake lines that lead to the evaporator core. I haven't worked on a 2g in that area in particular.

From what I remember both the thermo sensor and dual press sensors need to be operational for the A/C relay to engage and power the clutch. Both sensors work as protection mechanisms.

If you want to try and bypass them for 10-30 seconds max. You can jump pin 30 to 87 on you A/C compressor relay and see if cold air work. BUT FIRST make sure you have r134 in you system and it's not dry. If it is, go buy a small 10oz can and charge it up yourself, hose in Walmart for low side is like $10 and a can is about $10-15. Do that ONLY if there is no pressure on the gauges or the low side shows very low psi, it should be around 60-80 at minimum with a/c off .

I heard you can rent an A/c manifold in O'Reilly's or AutoZone, but don't quote me on that

 

[cswindel]

Please forgive me but I tested the harness side of the a/c compressor again and there IS NOT 12v going to the signal wire like i originally thought but there is 12v power. Must have looked at the connector wrong on the first go.

So with that, I will still procure a manifold gauge to measure the pressure because even if I troubleshoot all the electrical I could still end up with a failing system due to pressure requirements not being met. Or at least that is what I am gathering.

 

[cswindel]

Okay so I hooked up a manifold and did the first charge and on the second charge when you run the car there was no pressure drop on the low side so I forced the clutch on the compressor to engage. Pressure started dropping and I slowly added the second can. Got like 2 minutes in and the car died because rpm dropped super low. And now im left with the pressure readings as depicted. So this is definitely an electrical issue I would imagine. As a note when I initially hooked up the manifold pressure was zero on the HI and lo sides

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[Vladimir]

Your pressures were at 0 in the very beginning cause either the shop never added anything or it all slowly leaked out.

When you started adding the first can did you add it to both sides at the same time or through low side only. If low side only what did the pressure reach?

The reading that is on the picture indicates that your system is severely clogged. When you forced the compressor to start running, you bypassed both the pressure switch and thermo and forced the compressor to work while the system is clogged/ severely restricted. What that did is created absolute vacuum on low side and left whatever amount of r134 you added on the high side. I am actually amazed and impressed how you were able to create absolute vacuum on low side that takes skills ))).

What happened most likely is when you originally took your condenser and whatever lines off, you never protected the system from dirt and dust being introduced. If you did and put paper towels or whatever in the lines/condenser to protect it from dirt going in while it was off, you might have left a paper towel inside and put the system together without removing it . That severely clogged the system.

Only thing that you can do now is take the whole system apart blow through the lines clean with pure alcohol and compressed air. I'm assuming most likely your expansion valve/orifice is clogged and should be replaced because that's the number one suspect always, you have to replace your receiver/dryer as well when you do that. Evaporator and condenser can also get clogged but it's a lot harder to do.

I am very interested however which pressure did you obtain on the first can of you charged from low side only? Without forcing the compressor to run

Also make sure your lines are not bent anywhere

 

[pauleyman]

You never add to high side. Freon will equally distribute when the system is static. If one side stays at zero there is a problem.

 

[Vladimir]

You never add to high side. Freon will equally distribute when the system is static. If one side stays at zero there is a problem.

Yes, sir. That's why they sell charge cans with low side hookups. But he used a manifold and I'm thinking that both valves were open low/high when he started charging the system. Pressures should have equalized but he Forced the A/C ON and created vacuum on one side cause there is no flow.

Chances are there was nothing wrong to begin with besides the fact that the system was taken apart and clogged. I'm sure the shop never added the freon and the system is doing exactly what it is designed to do. There might not be any electrical issues at all. It's just the diagnosis was started backwards under the assumption there was pressure in the system. Now that he got the manifold it's obvious that there was none. And after him adding freon it's obvious that it's restricted. Everything is backwards as usual in the DSM community))

 

[pauleyman]

Yes, sir. That's why they sell charge cans with low side hookups. But he used a manifold and I'm thinking that both valves were open low/high when he started charging the system. Pressures should have equalized but he Forced the A/C ON and created vacuum on one side cause there is no flow.

Chances are there was nothing wrong to begin with besides the fact that the system was taken apart and clogged. I'm sure the shop never added the freon and the system is doing exactly what it is designed to do. There might not be any electrical issues at all. It's just the diagnosis was started backwards under the assumption there was pressure in the system. Now that he got the manifold it's obvious that there was none. And after him adding freon it's obvious that it's restricted. Everything is backwards as usual in the DSM community))

I concur. There is likely a blockage. You can open high side manifold when static but i see no reason to.

 

[cswindel]

Yeah so when I did take off the a/c components I used blue paper towels to plug holes

I had a reading of approx. 117 psi when I filled the first can and that was filling from the lo side only. I believe the hi side was at about 100 psi. I can't remember the HI side well because I was more focused on the LO side and just going thru the process correctly.

This is what I got when I went out this morning (gauge reading depicted). Temp is very different and much cooler so im assuming that caused the change. Also the engine has cooled off as well.

At this rate I might just delete the a/c. Too much stuff to go wrong is one system

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[pauleyman]

Yeah so when I did take off the a/c components I used blue paper towels to plug holes

I had a reading of approx. 117 psi when I filled the first can and that was filling from the lo side only. I believe the hi side was at about 100 psi. I can't remember the HI side well because I was more focused on the LO side and just going thru the process correctly.

This is what I got when I went out this morning (gauge reading depicted). Temp is very different and much cooler so im assuming that caused the change. Also the engine has cooled off as well.

At this rate I might just delete the a/c. Too much stuff to go wrong is one system

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That looks about right. Both gauges are reading the same. Compressor kicks on low side should be maybe 30 to 40psi and high side 150 to 250 depending on outside temp.

 

[cswindel]

That looks about right. Both gauges are reading the same. Compressor kicks on low side should be maybe 30 to 40psi and high side 150 to 250 depending on outside temp.

Should I try and kick it on or do you think it won't matter if there is a blockage even if I were to force the clutch to engage again

 

[dwb]

Did you pull a vacuum on the system with a vacuum pump after opening it up? Did you flush the system or add any oil to it?

 

[cswindel]

I looked up some YouTube videos and all of them had about the same steps that I followed:
- hook up manifold
- pull vacuum on just middle/yellow line
- open HI and LO side on manifold and let vacuum pull for about 20 min
- Result was about -28 in HG
- Closed HI and LO side on manifold and let sit for about 20 min
- Still had same vacuum after letting it sit
- Pulled additional 5 min of vacuum and still was at -28 in HG
- Closed off HI and LO side, disconnected vacuum pump and I did try to get some PAG 46 oil in the middle line (maybe like 0.25 of an ounce of even that) since some leaked when I removed the compressor
- reconnected yellow/middle line to manifold and then hooked up refrigerant to yellow line
- cracked open can and then opened tap so r134 started to flow in yellow line
- bled yellow line and the opened LO side on manifold.
- Let all the r134 get into system and made sure LO side gauge was stabilized before turning car on

 

[Vladimir]

At this rate I might just delete the a/c. Too much stuff to go wrong is one system

There is not much going wrong. The system is clogged with something for sure. Pressures equalizing in the morning does not mean it will work now. It will be the same issue again if you force the compressor ON. Expansion valve and dryer at the very least should be replaced.


Note tho. Since the pressure equalized in the morning and both sides showed about the same pressure , did the A/C attempted to very briefly running the compressor? Those pressures on the picture should make the clutch engage very briefly till low side goes low to vacuum again. Pressure switch will see it and cut the clutch again. But it should briefly cycle on its own when you press a/c button

 

[cswindel]

There is not much going wrong. The system is clogged with something for sure. Pressures equalizing in the morning does not mean it will work now. It will be the same issue again if you force the compressor ON. Expansion valve and dryer at the very least should be replaced.


Note tho. Since the pressure equalized in the morning and both sides showed about the same pressure , did the A/C attempted to very briefly running the compressor? Those pressures on the picture should make the clutch engage very briefly till low side goes low to vacuum again. Pressure switch will see it and cut the clutch again. But it should briefly cycle on its own when you press a/c button

No I haven't tried to turn the a/c on yet. I wanted to see if there would be any pressure changes on the gauges as the morning went on and how drastic those changes were

 

[pauleyman]

I concur that should be enough to turn on all on its own. If low side goes to zero id say yiu have a blockage. If it was open a l time dryer is fried for sure. I concur with previous posts on dryer and expansion valve. Ac isn't hard but it's tedious.

 

[cswindel]

Just to verify the next steps to take:
- Leave HI and LO side of manifold closed and don't let anymore refrigerant in
- Start car and try to run a/c
- Check manifold gauge
- If a/c compressor doesn't kick on and if 0 psi on LO side replace dryer and expansion valve

Which one is the expansion valve? It's not the dual pressure switch on the a/c dryer right?
Also am I looking for anything specific on the HI gauge?