[DeobandiPrince]

Hey guys. Bought my car without checking if the AC worked and trying to get it up and running before it starts to get hot.

Some quick points to mention:

• I pulled a A6D0 code from INPA
• When the car is on (whether or not the climate control and/or AC is on or off) I can see the AC compressor in the engine bay spin.
• Bought an AC recharge kit and when I use it, the pressure gauge shows 0 and as I begin to fill it up, I just hear a gas leak sound and smell really strong Freon. I wore a mask and tried charging it but it just continues to make a gas leak sound and a smell of freon and the pressure gauge on the recharge canister barely goes above 0. I can't really tell where exactly in the engine bay the hissing noise is coming from and from what I've heard of how toxic freon is, not sure if I want to stick my face inside the nooks and crannies of the engine bay.
• When I press the AC button in the car, I can see the revs drop a little at idle. When I turn it off, I can see the revs climb a little. Tested it enough times to know it's not a coincidence. I also used INPA and in the AC compressor tester, the indicator for "compressor active" would turn on whenever I turned the AC on and would indicate off as I would indicate off.

Here are some screenshots from INPA


It was a scalding day today and I was sitting in the car with the car blowing hot air for a 5-10 minutes before I took these screenshots. Interesting to note the "Print Cooling Agent" shows 0 bar of pressure.

Lastly, I ran a UV dye AC recharge kit and followed the lines all around and nothing showed up. I even checked (what I think is) the condenser from the lower front grill and still nothing. I did notice though that around the AC Pressure switch, some fresh green dye. There's so much crud and dirt around it that it was hard to get all of it off with a screwdriver but you can make it out here next to the coolant reservoir tank and windshield washer fluid bottle.



Is it a safe bet to say that I should replace the AC pressure switch from FCP euro? Or is it the whole line that it's attached to? Or am I not even in the right direction and based on the info provided, should I be looking else where.

Any guidance is appreciated!

[gbalthrop]

Originally Posted by DeobandiPrince

A6D0 code from INPA. When the car is on (whether or not the climate control and/or AC is on or off) I can see the AC compressor in the engine bay spin. [That pulley ALWAYS turns. There is NO Clutch on pulley, but rather a "Compressor Valve" inside the compressor causes the compressor to pump R-134a or NOT.]
Here are some screenshots from INPA:
Interesting to note the "Print Cooling Agent" shows 0 bar of pressure. [That's a MIS-translation of "Druck Kältemittel" which PROPERLY Translated is "Refrigerant Pressure" (in bar).]
Lastly, I ran a UV dye AC recharge kit and followed the lines all around and nothing showed up. [Did you check at the compressor shaft?] I even checked (what I think is) the condenser from the lower front grill and still nothing. I did notice though that around the AC Pressure switch [it's actually a Pressure Sensor that INPA would read on the Lower Left bar graph of your FIRST INPA screen (IF there were pressure ;-)], some fresh green dye. [That Pressure Sensor is located on the High Side, next to the Windshield Washer Fluid Filler Tube.]

You obviously have a LARGE leak. Your Refrigeration Oil (PAG Oil) will probably have leaked out, and that will leave an oily area around the leak, which will get coated with dirt. If the car is "new to you", and you don't know how long the leak has existed, the compressor may be toast, and you will need to change the desiccant. I believe your 2009 model has the desiccant incorporated IN the Condenser, which means you will have to change the Condenser, as opposed to simply inserting a new Desiccant Tube.

But rather than worry about replacement parts NOW, the FIRST thing is identifying WHERE the leak is. Unless the Pressure Sensor has been removed, or broken somehow, I don't see HOW that could leak that FAST. You do NOT want the Compressor Valve to run since you don't have any Refrigerant Pressure AND you have NO Refrigeration Oil. If you have an air compressor with controlled pressure at say 50 to 70 PSIG, and can hook that up to the refrigeration lines (remove the high side or low side Schrader Valve), you could probably find the leak, listening for a hiss, at least with a mechanic's stethoscope.

Your FIRST INPA ScreenPrint "Read Analog INPUTS" shows "0 bar" Refrigerant Pressure (lower-right bar graph), and 41C Evaporator Temp, which should be between 0C & 10C if system were charged and Compressor Valve pumping.

The DEFINITION of the A6D0 Fault Code, per either ISTA, or BMW Fault Code Lookup:
A6D0 | JBE: Control valve in A/C compressor | jbbf70 | Junction Box electronics
That is NOT the Pressure Sensor, but the Compressor Valve which causes the Compressor (shaft always turning since NO Clutch) to Pump Refrigerant (and Oil), or NOT.

That code has NOTHING to do with the Refrigerant Pressure Sensor, other than NO pressure signal from Sensor will prevent Compressor Valve from engaging. You said the Low Side gauge (on can tap?) showed 0 PSIG? That means the ACTUAL High Side pressure is "0" when system is at equilibrium (compressor NOT functioning). Manifold gauges (~$35 @ Amazon) would confirm that.

So need to find leak(s), and at least ONE of them is HUGE. Clues: Oil, Dirt on oil residue, compressor shaft, any fitting, stone damage to condenser tubes/fins, Dye if any previously added to system. If you have an air compressor, preferably a large tank so you don't need to run pump, rigging that up to one of the Schrader ports (Low Side or High Side) would give an audible hiss at leak site.

The Standard 90 PSIG setting would probably be safe for the system where high side pressures can be 2 to 3 times that. If in doubt, and can adjust to 50 PSIG, that would likely be enough to cause hiss.
George

[DeobandiPrince]

Originally Posted by gbalthrop

So need to find leak(s), and at least ONE of them is HUGE

Really appreciated your in depth advice and insight Thank you!

Not sure if you got a chance, but did you see the picture of the pressure sensor/switch and the UV dye around it? In the last picture I mean. Not sure if it's the line it's connected to, or just the sensor seal wearing out or something. Wouldn't that be a good place to start?

I actually just went back out right now to the car and had an interesting idea. Didn't want to buy things unnecessarily to I try my best to rule out things with the little tools and info I know. I took a pinch of sand from a playground and covered it around the pressure switch shown in the last picture and used my AC recharge kit to blast some refrigerant thru the system. As soon as I pulled the trigger, about half a second later, the sand I sprinkled around the valve was blown gently aside.

I think that would be a good place to start right? Should I just purchase this https://www.fcpeuro.com/products/bmw...RoC7ckQAvD_BwE or should I replace the whole line? Not sure how to replace AC lines or what part that is.

Thoughts?

[gbalthrop]

On my 3/2007 build 328xi, that Refrigerant Pressure Sensor is located just in front of the Washer Fluid Filler tube, on the High Side Refrigerant line running front to rear on top of frame rail. It is hidden behind a heat shield, and the heat shield is fastened by 3 nuts, ~ 8mm. I would suggest removing the heat shield so you can see the Sensor, and remove the Connector.

For a leak that large, either something is broken, or loose. I have NOT ever removed mine, but I can envision how someone in a rush could break the refrigerant line trying to get the Sensor Loose. OR, the O-ring may be grossly leaking, OR the Sensor itself may be broken or leaking. "Stuff Happens" when a "Mech-nik" who is NOT familiar with the system tries to "Fix" unfamiliar things (like the "Print Cooling" sensor ;-).

So carefully examine that Sensor after removing the heat shield, and see what is broken/leaking (BEFORE ordering anything ;-). Either the tube to which the Sensor Socket is joined is leaking, or the sensor is leaking. Could be a bad O-ring, but that should be a SLOW leak. What you describe sounds more like a broken Sensor OR broken tubing.
George

[gbalthrop]

Attached are 2 ISTA ScreenPrints showing procedure for removing heat shield & Pressure Sensor.
Note that Sensors (variable signal) have "B" prefix, and Switches (on/off) have "S" prefix in ISTA SSP wiring diagrams.
You SHOULD be able to completely remove heat shield by removing rear screw/nut.
Since your system has been open to atmosphere for XX days/months no need to draw off/depressurize system.
George

[DeobandiPrince]

Originally Posted by gbalthrop

Attached are 2 ISTA ScreenPrints showing procedure for removing heat shield & Pressure Sensor.
Note that Sensors (variable signal) have "B" prefix, and Switches (on/off) have "S" prefix in ISTA SSP wiring diagrams.
You SHOULD be able to completely remove heat shield by removing rear screw/nut.
Since your system has been open to atmosphere for XX days/months no need to draw off/depressurize system.
George

Update: I replaced the high pressure line and the sensor we spoke about. Payed a shop to vacuum and fill and still no AC. They said the held it under vacuum for 20-30 minutes and also checked pressures 20-30 min after filling and it held pressure fine. INPA screenshots attached below after driving the car for about 10-15 min.




Used INPA to verify that the AC compressor does turn on. When I press the snowflake button, the indictor on INPA lights up. With the AC off and I press the INPA activate button, the indicator on INPA lights up too. Cleared the A6D0 code but it comes back.

Not sure what to do? Compressor according to INPA seems OK. Maybe the mechanic shop filled it to the wrong amount wither too high or low?

INPA screenshots after turning off the car for about 20-30 min.


(Ignore the error message. Have had issues with INPA after doing a Windows repair install cause of some driver issues I was having with my graphics card)

[johnpham326]

Were you able to fix your AC? I’m having very similar issues with the same Compressor Valve error. I see that the EC-blower position in your last screenshot says “0”. I believe this is the compressor valve setpoint and should be about 5-7 when working.

My issue is intermittent. Half the time it works and works very well.

[DeobandiPrince]

Originally Posted by johnpham326

Were you able to fix your AC? I’m having very similar issues with the same Compressor Valve error. I see that the EC-blower position in your last screenshot says “0”. I believe this is the compressor valve setpoint and should be about 5-7 when working.

My issue is intermittent. Half the time it works and works very well.

I ended up noticing that there was no RPM differences when turning the AC on or off. I went ahead and replaced the compressor as well as the condenser. I did put in an older condenser from a pre LCI car since those have removable canisters for the desiccant where as the LCI ones have them built in and you'd need to replace the whole condenser just to replace the desiccant.

It's all working fine now.