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BMW A/C – Air Conditioning Non-Functional – Won't Turn On

April 14, 2010

This answer is applicable for many BMWs in addition to the one listed below.

Q
My wife has a 2006 X3 3.0i with 68K on it.  An air conditioning problem has reared its ugly head with the warm weather coming. She recently ran her air conditioner and it never got cold with it being about 80 degrees outside. She does run the air conditioner a lot, but 68K seemed to be very early for a problem to arise so I read through a bunch of threads on various forums.

You would know more, but this problem seems to be more common than I thought on both the X3 and the earlier X5. It varied from people “needing” a new evaporator for $2K from the dealer or a leaky valve fix for $200. It also seemed that people had mixed results when going to an independent shop or the dealer and the dealer almost always said it needed a new evaporator. With all that said I am looking for your opinion on the subject. Also, air conditioning in a car seems to be a very complicated thing so would a air conditioning specialist be a good route to go instead of a general independent BMW shop?.

A
Yes, there have been some common A/C problems with the X3 chassis, as well as many later BMW models, to include leaking evaporators and expansion valves. Naturally, your issue could be one of these or anything else.

If the system is not turning on, the most common fault would be low refrigerant (low system charge) and this would only happen if there is a leak. The other possibilities include faulty pressure switches, faulty compressor clutch, a fault in the climate control panel … etc. You will need some initial basic testing in order to determine what part of the system is at fault. The first test should be to check the pressure in the system. If it is lower than the shut-off point for the low-pressure protection switch, then it’s likely that you have a leak in the system.

In order to diagnose a leak, the system must be charged (with refrigerant) and then a leak detector is used to search through the system, looking for the source of the leak.

I would suggest that you stick with an A/C specialist or a BMW specialist (or dealer) that is familiar with the common faults on these models.

Once you have a diagnosis, we can check out the parts price and availability.

3 Comments
  1. Roadoman permalink

    Hi,same problem here 2004 x5 4.4 not blowing cold air. What I have confirmed. Compresser does not engage. Static pressures evan high and low around 85-100 (not at car now going by memory plus I drained evacuated and recharged refigerant), I get voltage to the compressor something like 3-4/v. I was told these systems send pulses to the compressor rather than the old systems or streight battery voltage. So anyway, you mentioned above causes. 1, compressor which seems most likely to me. 2,faulty pressure switch to me maybe not because I do get a voltage reading at the compressor clutch. 3, the climate control panel. Is there a way to diagnos the control panel? Also in another post someone mentioned to check the voltage requlator which I will do as soon as I get to the car.

    Thanks in advance
    Roadoman

  2. Roadoman permalink

    One more thing to add. With the compressor wire disconnected, I did momentaraly put 12/v to the compressor and the compressor did not engage. Hopefully this isn’t a no no for this system.

    Roadoman

    • For the moment, let’s center on the clutch not engaging when you applied voltage to it. The compressor clutch should have engaged with the 12-volts applied directly to it. You may have a faulty clutch unit. have you tried applying the voltage when the engine is not running, to see if you can hear a ‘click” at all? If there is a click, but it does not engage, the clutch is faulty. If no click, check the resistance of the clutch coil by applying your ohm-meter from the clutch input wire to the case of the compressor (I believe your unit only has one wire …. if it has two, go between the two wires). The sample compressor that I just tested, here, showed 3.7 ohms across the clutch coil. If you have an open circuit, the coil is faulty and, therefore, the clutch is faulty.

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