AC Problem
 

Now that I finally got my X put back together and took it for a drive, I realized that my Air Con is pretty temperamental. It only works when I'm moving at like 25-30+ MPH and sometimes doesn't work even then. It's not that it isn't cold, it just moves no air, because when the air does move it's like an icebox in my car. Anything I should look at to solve the problem? Common fixes? Whatever advice you can give!

Does the aux fan ever come on? AC when the car is moving but no ac (warm air blowing out of the vent) when the car is stationary points to a Aux fan that is not turning on.

No air movement from the vents means a bad blower motor. It may turn on depending on where the brushes are in contact with the commentator of the motor. Good Luck trying to fix that.

Well when I'm not moving there is no air at all, warm or cool. Air just stops flowing. Where is the Aux fan located or what should I check just to be sure?

Aux fan is located in front of the radiator. The fan that pushes air thru the evaporator coil is located behind the dash in a box-like structure.

Does the dash have to come out to check the latter of the two?

A video is worth a million words according to Confucius.

https://www.youtube.com/watch?v=St_S1xFv-mU

Sounds like it might be the blower motor resistor. Sometimes the fan won't work on low speeds but does on high.

https://www.youtube.com/watch?v=7_D-Ki_Kk2k

So after thinking about it, I’m not sure the blower runs at all. If the blower motor wasn’t working would cold air still enter the cabin through the vents, being pushed by the aerodynamics?


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The upper-right button on the environmental panel is a maximum fan speed setting for quickly clearing a fogged windscreen. Hit that - if it sounds like a hurricane in the car, the dash blower is working. It's pretty unmistakable....

Yes when my FSR fully went out, there was no blower at all. However, heat or cold air would still push through the vents if the air recirculation was turned off and outside air was pushed through by the pressure created by velocity.

Is there a way to visually inspect the FSR without just replacing it.

Don't think so. It's actually a solid-state device, like a transistor. Potted and near-impossible to open.

Okay so while I am looking. Is there anything relevant to my predicament in the engine bay relay/fuse box by the windshield washer fluid resivoir on the passenger side.
(Also where does the bottom of that little divider go to, because I may or may not have dropped a tool.)


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You can check for power and ground. If you have power going to the FSR and nothing coming out of it than the FSR is basically toast.

So with that being said, could I bridge some of the ports on the plug with a wire to see if it will solve the problem? That would answer wether or not it is the problem


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You will need to get a wiring diagram to know which terminal is supplying power to the FSR. Don't know what you mean "Bridging" some ports on the plug.

I would suggest you take it in and let a tech look at it.

By this I meant to take a piece of wire and go between the different plug pins on the plug to bypass the resistor to see if it’s the issue.

Oh, I don’t know if I would suggest that.

Assuming your envirnment controls are automatic (with didgtal displays etc. and NOT the manual rotary dial type, it's not a resistor and you risk causing some serious damage to your A/C system (namely the IHKA) by poking wires in there.

But here's the wiring diagram... N2 is the motor speed controller - what you are calling a resistor...

https://www.newtis.info/tisv2/a/en/e...-stage/nuR0BZ3

And it seems someone did actually open one of these up...

https://xoutpost.com/bmw-sav-forums/...r-fix-diy.html

Love the way people come up with inventive ways to fix cars. NOT. With so much electronics in these cars if you don't know what you are doing it will be cheaper, in the long run, to bring it to a qualified Technicians. I have been on this board long enough to read a lot of DIY projects gone bad.

You can short pins 1->4 and 2->5. The blower should run with full speed.

:iagree:

Lots of folks here know lots, lots of folks post like they think they do. I haven't met anyone here that hasn't given wrong advice or knows everything.

The folks that spend the least amount of time and money to get something fixed ask questions and wait for several posts before tackling the project. They do the troubleshooting necessary to be as sure as possible they are fixing the core issue. As said, they also know when they need to turn it over to someone more experienced, when they only know enough to be dangerous and they don't have the right tools.

Yep - that's very clear from the wiring diagram but I didn't want to suggest it, as getting it wrong could end badly. But at least it eliminates the FSR as the problem. :thumbup:

Not everyone can read wring diagrams well... ;)

If trying this, be aware that the 12v on pin 2 is live all the time (via F64 and F200.

While I did not end up attempting to bypass the sensor, I just ordered it and it turns out that’s all it was. Thanks for the good direction!


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Glad you got it resolved! My AC is acting up and I need to take it to the shop. It get's hot here in AZ! Even in the mountains!