[Kaz26]

I drove my car the other day for the first time in about 2 weeks and the AC wouldn't get cold. I drove for about 20 minutes and it was still blowing warm. I'm trying to troubleshoot it, but my knowledge is limited on AC systems and info seems scarce. Help figuring this out will be appreciated.

What I've checked:
I checked the fuses, they all looked good, then I checked the low side pressure refrigerant line with the car running, AC on full blast set to the coldest temp (60F degrees) and it seems rather high at 85psi. I haven't checked the high side yet. Ambient air temp was about 80 degrees when I checked the low pressure side.

When I looked at the compressor with the car running, the center part just spins constantly whether the AC is running or not. So it seems like the problem is related to the compressor in some way. I will post INPA screenshots below. I'm not sure what to look for in it, but maybe someone here will.

[dpaul]

You need to look at high side pressure as well but I'll make a guess anyway.

85psi is about right for 80oF if your compressor is not working. I would anticipate you'd see the same on the high side and if so, you compressor is not functioning. The absolute value of the pressure will change depending on the outside temperature.

The spinning you see is normal - there's an electric clutch inside. My guess is that your compressor clutch has failed.

Somewhere in INPA is a toggle to activate the compressor clutch.
Maybe: Body > Air Conditioning > Activate > Digital Output > Air Conditioning Compressor. Going from memory here, could be wrong. Anyway, google it. Activate it and you should hear a "click". No click probably means bad compressor clutch (but wiring issue could be the problem too)

Try looking here:
https://www.e90post.com/forums/showthread.php?t=1512155

[NinetyEight740]

85psi means compressor is not turning on. That is pressure at a standstill

[gbalthrop]

Originally Posted by Kaz26

I drove my car the other day for the first time in about 2 weeks and the AC wouldn't get cold. I drove for about 20 minutes and it was still blowing warm.
What I've checked:
I checked the fuses, they all looked good, then I checked the low side pressure refrigerant line with the car running, AC on full blast set to the coldest temp (60F degrees) and it seems rather high at 85psi. I haven't checked the high side yet. Ambient air temp was about 80 degrees when I checked the low pressure side.
When I looked at the compressor with the car running, the center part just spins constantly whether the AC is running or not. So it seems like the problem is related to the compressor in some way. I will post INPA screenshots below. I'm not sure what to look for in it, but maybe someone here will.

Your compressor is NOT operating. The key is in the SECOND screen you attached, which is actually the FIRST screen
in F1 AnalogPorts when you select that from the F5 Status Screen after connecting to the IHKA Module.
A correct translation of the German technical terminology used in INPA is found in the attached INPA IHKA Tutorial pdf.
I have attached a copy of that screen translated properly to English, with some additional Notes on the significance of the data.

1) The bar graph in the Lower-Left of that screen is HIGH SIDE Refrigerant (R-134a) Pressure in bar units, 1 bar - 14.5 PSI.
7 bar = 7 x 14.5 = 101.5 PSI & 101.5 PSI - 14.5 = 87 PSIG; The original German was "Druck Kaltemittel" = Refrigerant Pressure

2) The Evaporator Temperature (temp of the A/C cooling coil in dash) is shown in the 2nd bar graph from bottom on Right, degrees C

Refrigerant pressure of 6 or 7 Bar is certainly sufficient to engage Compressor Valve, so your issue is NOT low refrigerant.

Your Evaporator Temp (per sensor contacting Evaporator/ Cooling coil) is 44C which is 15C HIGHER than Outside Temp -- NO Compressor.

If you have manifold gauges connected to BOTH High Side and Low Side, BEFORE starting engine, after sitting overnight,
you would find the High Side & Low Side pressures equal, the system having attained equilibrium after ~ 5 hours static condition.

Measure the High Side & Low Side pressure any way available to you. That IHKA screen from INPA shows HIGH SIDE,
so if you have a charging handle/ Can Tap with gauge to measure Low Side, you can read BOTH. NOW, start engine and
with "Snowflake" LED on R side of A/C control panel lit and A/C MAX button pressed, see if either High or Low side readings change.
If they do NOT, then you have NO compressor operation. Check back with test results and someone can suggest "next steps."

COMPRESSOR VALVE:

The Denso Compressor used on (Most?) E9x models does NOT have a clutch
but rather uses a "Compressor Valve" to control whether
the compressor pumps R-134a or NOT. The Compressor Valve (Y2b) is connected to and controlled via the JBE Module.
The front of the Compressor ALWAYS looks the same, whether the compressor is pumping or NOT. You will see NOTHING
different as far as what is turning externally whether pumping or not. There is NO clutch plate to "click in" or turn when engaged.
Here are some links for more information about the Compressor & System:
https://www.newtis.info/tisv2/a/en/e...eos/1VnY9cKgnR
https://www.newtis.info/tisv2/a/en/e...ioning/25K67rA

Here is the TIS circuit diagram for Climate Control Functions on your 2008 335i E90:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

NOTE: the Refrigerant Pressure Sensor (B8) and Compressor Valve (Y2b) are BOTH connected to the JBE, and you
can also read information and Fault Codes (F4 Fault Memory/ Fehlerspeicher) by connecting to the JBE Module.

I'm NOT aware of any way to Activate or Control the Compressor Valve for test purposes, either when connected to IHKA or JBBF/JBE.

ANYONE knowing of any way to Activate or monitor actual Control Valve position please advise.

George

[dpaul]

Oh well, sorry for the misinformation about the compressor clutch which may not exist. Never replaced compressor on my E90 vehicles - 'click' must have been my E46 or E39 may they rest in peace.

[mecheng77]

Take a screenshot of the pressure in bar before turning the a/c at all in the last hour or so then another picture with a/c engaged after 10 min to see if the pressure changes

[Kaz26]

I checked the pressure again and it was pretty much the same this morning. So then I started the engine and ran the AC on Max at 60F and the low side pressure went up to nearly 100psi and the high side is now at 6.5 bar and seems to be staying there. So the high and low are indeed about the same pressure as predicted, and it seems to have plenty of refrigerant, so it's looking like a compressor issue.

I went in through INPA and found an activation ability for "Clima-compressor Relay KOREL". When I activate it, I can definitely hear it doing something. It isn't a "click", but it sounds like it's putting a very small, but discernibly audible load on the engine.


Does the compressor need to be replaced or if something else is causing the compressor to not run properly?

[Kaz26]

After some searching, I found a youtube video where a guy was troubleshooting a very similar situation with his AC on an X5 and his problem ended up being the pressure sensor switch. His error codes were different, but it got me to look in the same place in INPA. in "Body>Junction Box Passenger>Error Memory.

The errors I found are:

A6CF - AUC Sensor
A6D0 - Kompressorventil


** For those who want to access the compressor actuator Activation, it's found in INPA in the "Engine" section under Component Triggering, then Actuator Activation 1. You will then see it on the bottom left side.

[gbalthrop]

Originally Posted by Kaz26

...The errors I found are:
A6CF - AUC Sensor
A6D0 - Kompressorventil

** For those who want to access the compressor actuator Activation, it's found in INPA in the "Engine" section under Component Triggering, then Actuator Activation 1. You will then see it on the bottom left side.

That's why most folks START with reading Fault Codes.

In this case the AUC Sensor and Compressor Valve (as well as the Refrigerant Pressure Sensor) are ALL connected to the JBBF/JBE, per the attached TIS "Heating & Air Conditioning Functions" circuit diagram:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq

So you need to read fault codes in the JBBF as well as the IHKA module. Here's what BMW Fault Code Lookup provides for a Definition for A6D0:
A6D0 | JBE: Control valve in A/C compressor | jbbf87 | Junction Box electronics

That code, taken together with the lack of development of ANY High Side Pressure when static system pressure is 7+ bar, points rather clearly to a bad Compressor Valve. A replacement Valve is available for ~ $40 I believe, but I'm NOT sure that anyone recommends just replacing the valve, rather than installing a Reman Denso Compressor, given what is involved in removing the Compressor to replace the valve.

BTW, if you could copy & post INPA screens of the following here, it would be very helpful:

1) the Fault Details when you read the A6D0 Fault in JBBF. If you just read codes in Functional Jobs, you need to connect to JBBF and get the FULL DATA on both A6D0 & A6CF.

2) the DME > F6 Activations Screen used to Activate the Compressor Valve; are you referring to the F6 | F1 | Shft+F2 "KOREL" (Compressor Relay) screen?

Thanks for helping us learn from your experience,
George

[dpaul]

Originally Posted by Kaz26

After some searching, I found a youtube video where a guy was troubleshooting a very similar situation with his AC on an X5 and his problem ended up being the pressure sensor switch. His error codes were different, but it got me to look in the same place in INPA. in "Body>Junction Box Passenger>Error Memory.

The errors I found are:

A6CF - AUC Sensor
A6D0 - Kompressorventil


** For those who want to access the compressor actuator Activation, it's found in INPA in the "Engine" section under Component Triggering, then Actuator Activation 1. You will then see it on the bottom left side.

well done Kaz26! Looks like compressor valve indeed!

[kkasson]

It's too bad that code description is so vague - I wonder if it's a circuit problem or a problem with the valve itself. The description of the problem (worked fine, sat for 2 weeks, doesn't work at all) makes me think it might be a wiring issue. Rodent damage, maybe?

Unfortunately it's probably difficult to find information on how to actually test the circuit, but you might try to visually inspect the wiring to the compressor.

[Kaz26]

We do have rats around here and in the past have found rat droppings in engines of previous vehicles, but I don't see any signs of that right now. I will look at the diagrams and follow the wiring the best I can. I will also find the sensor, check if it has electricity running to it and if so, I will try to test the sensor, or just replace it.

I'm attaching the screenshot of the two errors in the JBE and also a screenshot of the compressor activation I mentioned prior. Maybe the supplied additional numbers will mean something to one of you.

Thank you for the support, I appreciate this very much.

[kkasson]

Originally Posted by Kaz26

We do have rats around here and in the past have found rat droppings in engines of previous vehicles, but I don't see any signs of that right now. I will look at the diagrams and follow the wiring the best I can. I will also find the sensor, check if it has electricity running to it and if so, I will try to test the sensor, or just replace it.

I'm attaching the screenshot of the two errors in the JBE and also a screenshot of the compressor activation I mentioned prior. Maybe the supplied additional numbers will mean something to one of you.

Thank you for the support, I appreciate this very much.

The AUC sensor is the air quality sensor which is near the cabin filter under the hood. Super simple to replace it, but it shouldn't affect the AC compressor. It might prevent the auto-recirculate from working, but the AC itself shouldn't be affected.

There's also a refrigerant pressure sensor on the high pressure AC line. I believe that's the sensor that was bad on the X5 you mentioned. That sensor seems to be working on yours, since the pressure readings in INPA are correct. You have to evacuate the system to replace that one.

Running the German through Google translate, it says "no signal or value" for the compressor valve. That again makes me think it's possibly a wiring issue, although if the valve is actually dead and open circuited it might cause that as well. I'm not sure how easy it is to see the wiring for the compressor, but I think visually inspecting it is probably your best bet at this point. Be careful that you don't disconnect any actual hard parts of the AC system since it's still pressurized.

[Kaz26]

I will do a visual inspection as best I can, but it's looking like I will need to remove the compressor no matter how I look at this situation... In which case, I will definitely replace the compressor, and probably with a new one. I have no problem doing it myself, I will just need to find someone to evacuate the lines first.

If I'm going to have to evacuate the lines and pull the compressor, it would probably be a good idea to replace other parts that might be going out soon. All suggestions on parts to replace would be appreciated.

Thank you again for all of your help!

[gbalthrop]

Originally Posted by Kaz26

...I will look at the diagrams and follow the wiring the best I can. I will also find the sensor, check if it has electricity running to it and if so, I will try to test the sensor, or just replace it. I'm attaching the screenshot of the two errors in the JBE and also a screenshot of the compressor activation I mentioned prior.

Thanks for the ScreenPrints, and thanks for the tip on the F6 Activation of the Compressor Valve being in the DME Module Menu. I had looked in IHKA & JBBF/JBE (to which the Compressor Valve is wired according to TIS) and NOT found it. If ANYONE has a good theory of WHY it's in DME, please advise.

Actually, upon further inspection of the circuit diagram, the wiring from the Compressor Valve goes FIRST to the E-box, so that probably answers the question, as the DME is the closest module to the Component for purposes of reading or over-riding (Activating) the Activation Signal from the JBE. NOTE that Connectors X6011 AND X60551, through which the JBE PWM signal passes on its way to the Compressor Valve are ALSO in the E-box.

I will attach a jpg of Kaz's Fault Memory Screen with English Translation (per Google Translate) to the next post so as NOT to mess up the margins here. Several things are curious upon reviewing the translation:

1) The AUC (air quality) Sensor Fault Code was saved 5 miles/8 km BEFORE the Compressor Valve Fault;

2) The AUC Sensor Fault is NOT currently present. Therefore, I would simply delete the code and see if it returns.

3) The nature of the AUC fault is "Implausible Signal or Value" which, taken together with the fact that the fault is NOT present at whatever later mileage the fault codes were read, suggests that there WAS some wiring fault, perhaps a dirty/ wet/ corroded connector. I would separate the connector and clean pins & sockets with Contact Cleaner. AUC is on Right vehicle side of the upper microfilter housing at the firewall under the hood. "Installation Location" in TIS can be accessed by clicking on BLUE component ID# (B414) in this A/C Functions circuit diagram, and getting the second link below:
https://www.newtis.info/tisv2/a/en/e...bution/uZS1ONq
https://www.newtis.info/tisv2/a/en/e90-335i-lim/R8EZFJj

4) Transitioning to the Compressor Valve Fault, I was trying to find some common connector or element to explain WHY the two faults were saved within 5 miles of each other. The ONLY common factor I can identify is that BOTH components receive a PWM signal from the JBE (via different connectors), but I don't know enough about how PWM signals are generated to know if that's significant or NOT.

5) As "KK" observed, the NATURE of the Compressor Valve Fault (A6D0) is "NO Signal or Value" and that could be a wiring or connector fault, including a bad Ground. So I would check the Connector to the Solenoid Valve at the Compressor, and the other connectors between the Compressor Valve Connector and the JBE.

It would be a shame to go to all the trouble & expense of pumping out the system installing a new compressor, evacuating, recharging, etc. ONLY to find that there is a wiring issue and the new compressor doesn't pump either. If I were faced with that problem I would not ONLY inspect the wiring/ connectors visually (checking for damaged pins/ sockets) but I would ALSO test the wiring electrically for continuity, from the Compressor Connector to the JBE if possible. NOTE that X6011 & X60551 are BOTH in the E-box next to each other per this "Installation Location."
https://www.newtis.info/tisv2/a/en/e90-335i-lim/S7vd3wc

HOLD THE PRESSES!! I was about to hit "Submit" when I realized I wasn't clear on what you did when you "Activated" the Compressor Valve using F6 | F1 | F9 KOREL, so I go back to your post #7 and read:

"I went in through INPA and found an activation ability for "Clima-compressor Relay KOREL". When I activate it, I can definitely hear it doing something. It isn't a "click", but it sounds like it's putting a very small, but discernibly audible load on the engine."

So AFTER selecting "Korel ein" or Compressor Valve ON, and hearing/feeling a slight engine RPM/Load change do you get any cooling? How long will the Activation over-ride make the circle dark at bottom left of INPA screen? Can you quickly go to IHKA Module & monitor Refrigerant Pressure (High Side) & Evaporator Temp to see if Compressor is pumping, OR if you have Manifold gauges, can you see a pressure change. Leaving DME Module to check IHKA may result in return of control to DME/JBE, and result in Compressor Valve shutdown -- no pumping.

What I'm wondering is if there is a wiring fault BETWEEN the JBE and the E-box, such that DME over-ride/ Activation causes the Compressor to pump, whereas the JBE signal either doesn't exist or get's lost before it gets to the Compressor. Quite a puzzle.

Please let us know what you find,
George

[gbalthrop]

Here is the Translation of your JBBF Fault Memory Screen;
Also attached is DME KOREL Compressor Valve Activation Screen:

George

[Kaz26]

Thank you for the thoughtful and thorough response. Truly appreciated. I will do these checks again in the morning and pay attention to these things. When I did it I was only listing to hear if it was engaging. I should have investigated further with it. Also, I did clear the codes and what’s weird is that it seemed to feel like it started getting cold, but then went back to warm. I will try it again in the morning and also try to watch the pressure and evaporating temp next time. Another thing I should note, now that this is heading into the ebox, is that I have a JB4 connected. Could that have caused this at all?

I will make another evaluation tomorrow and with a little luck I will find a wiring problem that’s easily repairable. Your logic on the area by the firewall sounds solid, I will look there first. Thank you!!!

[dpaul]

Originally Posted by gbalthrop

Thanks for the ScreenPrints, and thanks for the tip on the F6 Activation of the Compressor Valve being in the DME Module Menu. I had looked in IHKA & JBBF/JBE (to which the Compressor Valve is wired according to TIS) and NOT found it. If ANYONE has a good theory of WHY it's in DME, please advise.

Actually, upon further inspection of the circuit diagram, the wiring from the Compressor Valve goes FIRST to the E-box, so that probably answers the question, as the DME is the closest module to the Component for purposes of reading or over-riding (Activating) the Activation Signal from the JBE. NOTE that Connectors X6011 AND X60551, through which the JBE PWM signal passes on its way to the Compressor Valve are ALSO in the E-box.

Just a thought, DME needs to be involved because idle has to be adjusted to account for increased load.

[Kaz26]

Haven't had time to get to it. Though a visual inspection hasn't shown anything obvious. I will check the leads for continuity this weekend and hopefully something presents itself.

[Kaz26]

To those who said it sounds like rats, they were right. I will post a pic below. I probably should have just looked at the wire going to the compressor from the start, but instead I was trying to locate and test leads. No signal led me to follow the line to what you see below. A rather obvious problem had I looked there to begin with...

I will solder it up in the morning and hopefully the problem will be resolved. Thank you for the help!!

[Kaz26]

The damage was worse than I realized and I had to replace an entire section rather than just reconnecting the lines. I would like to replace the entire line if possible, but it connects to the junction box located under the intake manifold and I cannot find any information on whether it can be opened up so I can replace just that wire with the connector.

Advice on this will be appreciated. Below are screenshots of how INPA looks now that the line has been reconnected.