Fault Time Condition
The fault is entered if the refrigerant pressure does not rise to over 2 bar after 10 s.

Service Plan
Low refrigerant level in the refrigerant circuit is suspected. Top up refrigerantCheck refrigerant circuit for leaks

 

This is what I don’t understand because isn’t 100psi > 2 bar

 

yes 100 psi is greater than 2 bar....however, if the compressor kicks in, there are 2 sides to the system...low and hi pressure sides. when you stated gauges (plural) in assuming you attached both lines.100 psi static pressure from a distance seems low, as in an undercharged system, possible leak. with the gauges hooked up, you see 2 different pressure reading from the 2 sides, hi and low sides, when the compressor kicks in. 2 bar is about 28 psi. find and fix the leak, recharge the system by emptying it of refrigerant, vacuuming the system and recharging with the proper volume, by weight, of refrigerant.

 

Ok, gauges installed. 100psi static pressure. Start vehicle and turn on A/C. Gauges don’t move, radiator fan does not come on. Check for voltage at compressor and test light does NOT light on positive side, I do however have a good ground. fuses 8-11-31-44 check out good…

 

BMW F25 X3 xDrive28i SAV / Repair Manuals and Technical Data / 64 Heating and air conditioning / 64 50 Air conditioning, check /
64 50 ... A/C performance test
[ … ]

• If there is no refrigerant loss, continue troubleshooting using the pressure measurement (only possible for vehicles with unregulated air conditioning compressor up to series E46/E53).

BMW F25 X3 xDrive28i SAV / Repair Manuals and Technical Data / 64 Heating and air conditioning / 64 50 Air conditioning, check /
64 50 ... Troubleshooting by pressure measurement (R 134a)

Note: The troubleshooting by pressure measurement described in the following is only possible on A/C systems with uncontrolled compressors.

This includes among others:

• E53
• E46M47 up to 09/2001
• E38 up to 09/1997
• E36, E36/7
• E34
• E32
• E31

 

Also, I have code C90D60 (AUC sensor bad)
is this the issue…

 

auc code wont affect ac operation

 

I didn’t think it would, I’ve had that code for two years now and the A/C worked before…

 

Disconnect battery for 60 minutes.
scan vehicle, only code is for AUC sensor.
I disconnect wires at A/C compressor and rescan. Fault shows open circuit at A/C compressor.
reconnect and clear codes. No faults.
I can go in with my scanner and A/C pressure shows 5 bar. (It’s cooling down outside)
start car and turn on A/C, scanner shows compressor “ON” A/C pressure on scan tool dosent move off 5 bar.
no voltage at A/C compressor, I do have a good ground…

 

When you turn the AC on have you put your hand on the fat line/low line and felt if it got even slightly cold? Just a change in temperature.

 

The suction and discharge lines are the same temp.
suction does not get cold and discharge does not get hot…

 

So if its not changing in temperature, and the compressor is working, sensors are working, and the fan is blowing... then doesn't that mean you are low on Freon? Have you tried charging at all? Or have you tried draining the system and then recharging? I think to drain properly you'd have to go to a shop so you don't pollute or even risk injury or inhaling that stuff. I'm in no way a pro, just trying to think out loud with you.

 

NGU here. Top of my head, FWIW: I have older BMWs. On my cars the only electric connections the compressor has, I believe, are to the electric clutch which engages the belt-driven pulley to the compressor input shaft, turning the AC on. This clutch is part of the compressor assembly located between the pulley and the compressor frame.When you turn on the AC the electric clutch should click, if you are listening under the hood. You can not observe visually whether the compressor is going or not as you can't see whether it is internally turning. So, a possibility is the compressor is not getting turned on.
Suggest you check fuse(s), see if power is getting to the AC clutch and whether the clutch is activating. If the clutch has failed, be aware that BMW does not sell the clutch separately, They sell only the complete assembly of pulley, clutch and compressor at a high price. I think an after-market AC clutch is available from the usual online sources, if you need one.

 

The reading of 100 is good and bad, bad because it means there is a leak, good because you may get away for now by just adding refrigerant, since there is a small amount, means that there may not be humidity in the system, make sure to follow the refrigerant’s can direction.
When ready to do the repairs, start with the basics, the shrader valves, replace them always before you pull a vacuum and refill.
good luck

 

ambient temp 85, standing pressure 100psig the compressor should start. check fuse, high and low pressure switches

 

this is what I have been trying to say the whole time. compressor should run for at least 10 seconds.
I’m glad you see this, prob the only person so far.

scan tool shows 5 bar @ 75*F so I assume high side switch is good. ( I think it’s a PSI transducer actually)
I don’t see a low side switch in the schematic, only evaporator temp switch.
fuses 8-11-31-44 are all good. All fuses are good behind glove box.
I can activate the A/C control valve inside the compressor with my scan tool, I can hear it move when activated.
I can activate the compressor clutch with my scan tool, the compressor clutch itself dosent do anything.
I disconnect electrical connection at compressor clutch and I get an open circuit on my scan tool.
I install test light at compressor clutch and activate with my scan tool, test light does NOT light up.
I have a good ground at compressor clutch.

 

I haven't had the need to work on my A/C in the x3 but have on my other vehicles and they had high and low switches. If the x3 has transducers they can still be checked. You may have a bad clutch

 

im going to check resistance across the compressor clutch tomorrow. If it’s good I will Hotwire the clutch and see what it does.

 

I thought you had voltage to the clutch, my bad.

 

12 OHMS at compressor clutch.
jump compressor clutch (with engine off) and clutch works…

 

Ok so the clutch coil is not open or grounded thats good. Relay,low or high pressure control / transducer or a switch somewhere

 

He is on the right track. Glad the clutch is not toast as that would have been a pain to fix.
12 ohms means around one amp of current operates the clutch normally.
He didn't jump the clutch with the engine-on to do a quick/momentaryAC function test. I don't think that would be risky, do you?
I'm just wondering whether there is something broken in the chain of connections that provide voltage to the clutch or whether the engine management system has chosen to shut down the AC as a result of some detected fault. I lean strongly toward the connection fault being to blame.

 

Update: apparently the electrical connector at the compressor clutch needs to plugged in when checking for voltage at the compressor. I have been checking for voltage at the clutch with the connector unplugged numerous times with no voltage. When I hot wired the compressor clutch (with engine running and gauges on) my pressures never changed. I decided to test for voltage with the electrical plugged in to the compressor clutch and my test light lights up every time I turn on he A/C.

Now, is it the compressor bad or is the control valve in he compressor bad. I can activate the control valve with my scan tool and nothing changes…

 

Hi! I don't have any reference material here, so I cannot say anything about the control valve. iI'm not familiar with it. I suggest you confirm that the clutch activates when you hotwire it with the engine running and the AC switch on. You should hear it click on, I'm pretty sure. If it activates, then the compressor has to be turning. If no ac cooling results and no coolant pressure changes are seen, I suppose it could be the valve. the compressor or something in the refrigerant pathways.

 

Kinda weird compressor. The front pulley is always turning the compressor shaft. The clutch is in the back of the compressor. And some type of a solenoid control valve for maybe a partial load or a Freon bypass of some sort.
I called the dealer and they show no such part (A/C control valve) that mounts on the compressor but it’s clearly there. dealer suggest it comes on the new compressor but Every new compressor I find has a mounting position on the compressor for this valve but no valve. I think it’s an N52 (2011-12) only thing because the N55 and the 4 banger both use different compressors.

 

Kinda weird compressor. The front pulley is always turning the compressor shaft. The clutch is in the back of the compressor. And some type of a solenoid control valve for maybe a partial load or a Freon bypass of some sort.
I called the dealer and they show no such part (A/C control valve) that mounts on the compressor but it’s clearly there. dealer suggest it comes on the new compressor but Every new compressor I find has a mounting position on the compressor for this valve but no valve. I think it’s an N52 (2011-12) only thing because the N55 and the 4 banger both use different compressors.

The pulley is always turning when the engine is running, but the compressor shaft is not turning unless the clutch is engaged/activated. Did you confirm whether the compressor is actually turning?

 

So it appears I’m really stupid or maybe I’m just learning as I go.
there is no clutch what so ever, even though my scan tool shows a clutch activation test option.
It’s direct drive. the A/C compressor is always turning with the engine. There is however a PWM compressor control valve, my scan tool also shows this and I can activate it.
the control valve adjusts a swash plate inside the compressor that varies the displacement of the A/C compressor.
it can vary anywhere from 0% to 100% load. This part comes with a new compressor and is mounted in the back of the compressor. I was confusing this with a rear mounted electrical clutch magnet. There is one aftermarket company that offers this control valve (they say it’s a high failure part) but the entire compressor needs to be removed to replace this valve and is one hell of a job. If this valve is bad the swash plate is stuck in 0% load and would explain everything…

 

So it appears I’m really stupid or maybe I’m just learning as I go.
there is no clutch what so ever, even though my scan tool shows a clutch activation test option.
It’s direct drive. the A/C compressor is always turning with the engine. There is however a PWM compressor control valve, my scan tool also shows this and I can activate it.
the control valve adjusts a swash plate inside the compressor that varies the displacement of the A/C compressor.
it can vary anywhere from 0% to 100% load. This part comes with a new compressor and is mounted in the back of the compressor. I was confusing this with a rear mounted electrical clutch magnet. There is one aftermarket company that offers this control valve (they say it’s a high failure part) but the entire compressor needs to be removed to replace this valve and is one hell of a job. If this valve is bad the swash plate is stuck in 0% load and would explain everything…

That description makes sense, but I wonder why they would design it that way. I guess it allows the load on the compressor to be variable. I don't like it when systems get more complicated and failure-prone (control valve and swash plate add complexity as opposed to a simple clutch) without an obvious major advantage of some kind. I have had 4 BMWs, the first with no AC. I don't expect to have another. Best of luck,

 

whats really confusing is this stupid scan tool shows both a compressor clutch active test and A/C control valve active test so I was believing it had both. I believe it’s designed for a few reasons, better fuel economy, better constant cabin temperature and the slamming of the compressor from the clutch turning on and off….

 

Hmmm. I can see the fuel economy improvement as real. And meaningful in Europe where gas prices are about double those in the US. Our cars drop their mileage 2 or 3 mpg with the AC
on. The variable load design that you have probably saves a mpg when the AC does not need to work at full output, The turn on jolt that a clutch produces does not sound to be too problematic to me.
So, they have gone to a more complex AC system design with variable compressor loading which involves additional sensors and more elaborate control circuitry vs. basic on/off functionality. I'm not sure I like the tradeoffs.
.

 

Sounds like you're chasing your tail treating this system like an old school clutch type compressor. Many modern vehicles use clutchless variable displacement compressors with PWM signal to command the control valve within the compressor. These variable compressors have been in use for a long time for improved efficiencies. There's logic that reads several different sensors to determine the PWM frequency to send to the compressor. I don't know what diag tool you're using, but I suggest using ista+ to aid in diagnosing your a/c issue, or take it to a professional

 

not really chasing my tail when I pretty much figured this out on my own when everyone else was insisting it was low on Freon. Where were you 15 days ago. I’m 100% capable of making the repair…

 

@BIG_KID Did you figure it out?

 

Im in the same boat - Scan tool shows 2 bars, AC shows as "On" in my scan tool, all fuses are good. My freon was low when checked and I topped up from what was less than 30 to now 50 PSI. Does the X3 run higher than 50psi? I went hunting for the info and will take it to the shop next but if I'm only half the pounds, Ill at min top up before I hit the shop.

Anyone know the PSI spec?

 

its not that simple as a set PSI spec, unless ones evacuates all of the refrigerant and refills with the correct volume of the correct refrigerant by weight, that is the only way to ensure correct refrigerant fill. reading pressures will not give one the an exact fill. ambient temp, vent output temp etc come in to play.
50 psi does seem a bit high, but again, variables.