2002 BMW 540I air/conditioner not blowing air at all.
Hello, This beauty is is sadly killing me softly. Driving down the freeway and the AC and air stops blowing. No air. I pushed all different kinds of combinations of AUTO/RECYCLE and cannot get air to blow out. I replaced the cabin air filters just to make sure they were clean but now the air will work on and then turn off when it feels like. I can turn on the car and it will work, then if I turn off the car and get back in from work the ac/air bill not blow out. I can hear something turn on when I turn on the fan and ac buttons but nothing blows out. Then some days it will work like a charm cold and strong. Any ideas?
Re: 2002 BMW 540I air/conditioner not blowing air at all.
It is the Final Stage Unit/Blower Motor Resistor - changed mine and the problem never came back. After two tows and drained batteries. Most mechanics don't seem to put this one togther - you have to demand it. Funny because it is a VERY COMMON problem in BMW.
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sounds like at hi speeds the air is blowing over the intake below the wipers. because the shape of your hood it makes the air go over the intake. check your cabin airfilter, it may be clogged. if it has one it will be behind the glove box
If there is air moving through the vents most likely the final stage transistor(blower resistor) has failed. It controls blower speed from a signal from the ihka (a/c control panel). the final stage receives the signal from the ihka of the drivers preference blower speed. the final stage pwm (pulse width modulates) the blower motor. which means it turns it off and on very quickly to speed up or slow down the blower motor speed. It isn't the easiest part to replace. Usually at a dealership i would expect to pay somewhere around $600 (including diagnosis)but don't hold me to it. bmw dealerships stand behind their repairs and usually include a warranty with the part of 2 years unlimited mileage.
You may have a low charge of freon, most likely about 10 ounces, as far as the musty smell that is mold from the inside of the AC air box, they make various chemical tratments to cure this issue, but once the smell is there it can be diofficult to kill the mold that causes it.
The reason your A/C sent hot and dash showed -40 is because you probably lost your amibent sensor. Its a sensor that reads the tempature outside and if its cold it will not allow your a/c to work, if you force it, you'll cause far more damage then you'd like. You can go to www.bimmerspecialist.com and find an ambient sensor. Also check www.bimmerfest.com to get pictures where your amibent senor is located. Mine was in back of the front / passanger sensor, and it got ripped off as I hit something on the road. Hope this helps...