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Summer is here and temperature is rising. I've searched the forums on how to fix my AC. My problem was the compressor was not turning on. I've read that if you have low freon (r134a), the compressor would not start. however, it seems as if most people have it start when the car starts but turn off when it realises it has low gas, or consititly switch on and off indicating low gas. So my problem was it didn't switch on at all, not during startup or anything. It seems the power cable leading to the compressor is not on properly. the connector looked like it was on but was very loose. So, if you were diagnosed with a bad compressor or heater valve, or something like that, check this connecting first. It could save you thousands. Really! Some places asked $2000 just to replace the AC Compressor. Post back with comments if this little Fix helped you out.
 

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it's the temperature switch located in the compressor. the wires are indeed very thin and can easily loosen on the connectors.

i'm sorry but i don't have pics of this connector, but it's part # 64528375442 on my 316i (yes, believe it :) I'm from the Philippines). you can check how it looks like on this site : http://bmwfans.info/parts/catalog/E..._air_conditioning/air_conditioner_compressor/

I hope this helps, I just discovered this today as well. mine was not turning on as well, I lightly touched the wire and then the compressor engaged. just a loose connection
 

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Just to clarify, if your compressor clutch is engaging, then this is not the issue, right?
 

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Here’s the sequence of events that happen when you press the AC button (aka snowflake):
- the climate control module (IHKA) checks the outside temperature* and the engine temperature
- IHKA checks the refrigerant pressure switch which is located on the dryer
- IHKA sends an “activate compressor clutch” request to the engine computer (DME)
- either the DME or the IHKA activates the AC compressor clutch relay
- the relay sends 12VDC to the compressor’s clutch

* The ambient air temperature sensor is located in the area between the left front wheel liner and the front bumper. If it’s sending says the outside temperature is low the sequence outlined above doesn’t happen.

So the first thing to do is to see if there’s 12VDC at the compressor clutch connector. If not, check the wiring between the connector and the relay. The AC relay is located in the relay panel above the fuse panel.

https://www.realoem.com/bmw/enUS/showparts?id=BN53-USA-07-2000-E46-BMW-330Ci&diagId=61_3382

You did check the fuses?
 

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Not 12 years ago, I had a problem with the A/C not engaging.
Hooked up PASoft, which said the car had a problem with its cooling fan
(only one because manual car)

Come to find out, on a number of cars, BMW's wire jig wasn't correct, and all the tension from
the harness to the fan connector was being borne by the 'activate' line to the fan controller.
Fast forward 12 years, and the wires are breaking. In our case, it looked like someone had
cut a 1" section out of that little wire. In junkyard cars, I've seen everything from that to
a small break in the copper and a stretched jacket.

Anyway, the short of it is, scan your car if A/C doesn't come on.

And beware of NecroThread!

heh

t
 
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