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Discussion Starter #1
Howdy, I went to fill the system up with freon, I thought that's why it's not blowing cold air, found out that the ac clutch is not engaging, what can be the problem? electric?
Thanks
 

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There is a series of thinks that have to happen before the electric AC clutch will engage.
  • the pressure switch on the R134a refrigerant (Freon hasn’t been used in decades) dryer has to tell the climate control module in the dash (IHKA in BMWspeak; IHKM if it’s a manual module) that there’s a proper amount of refrigerant in the system
  • the ambient air temperature sensor has to tell IHKA/IHKM the outside air temperature (the system won’t work if the sensor is missing or disconnected; it’s located in the cavity between the left front tire and the front bumper)
  • the IHKA/IHKM has to send a request to the engine computer (DME) to enable the AC compressor clutch (this allows the DME to shut off the AC if the engine is running hot).
Now, the first thing is to make sure the AC fuses are good. They are fuses 28, 62 and 63. Next, there’s a relay located above the fuse panel in the glovebox. The link below will show you where the relay is located.


Also, the AC system in the E46 is sensitive to overfilling and underfulling of R134a. The only way to know if the system has the proper amount of R134a is hook up gages to the low and high sides of the system. The connectors are easily accessible under the hood. Now, the clutch is engaged when 12VDC is applied to the small connector near the clutch. With the engine running you could unplug the connector and apply power to the compressor’s connector. That’ll tell you if the clutch is ok.
 

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Put 12V on the A/C clutch, and see if it engages. If not, it's broke. If it does, there's a chance the A/C relay is toast. They do go bad. Had to replace mine only a couple months ago.
 

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Discussion Starter #4
I checked the fuses and they are all good , i was last week at the service , they put 700ish grams of freon in the system , when i turn the car on the ac automatically enables too(the snow flake button) if you know how to disable this it’s annoying in the winter, i will check with a 12 volt in the weekend , thats when i got time , also i is will check the relay too, I’ll be back with updates when i manage to do these steps , thanks for advices
 

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you can check it with PA soft. You can see 3 lights
  • A/C Button (lights up if your snowflake button is pressed)
  • A/C request (only lights up if your snowflake button is pressed AND if there's enough pressure and if it's not freezing outside, so if this light is on, it's a sign that the pressure sensor should be working, and that it wants to engage the A/C compressor
  • A/C compressor (if this lights on, but still compressor won't engage, relay is fucked. This was the case with me. Relay has 2 outputs, one to the DME and one to the compressor. My output to the compressor was fucked, yet the DME thought that it was engaged)
 

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Discussion Starter #6
I checked the relay is good , it gives electricity, maybe the clutch doesnt work anymore , will see in the weekend
 

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As suggested above, apply 12VDC directly to the clutch connector. 700 grams of refrigerant is roughly 1.54 lbs. I’d search this forum to find out if that’s the proper amount of R134a. The E46 AC system is sensitive to under and over-filling. Did you add any compressor oil?
 

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Discussion Starter #8
As suggested above, apply 12VDC directly to the clutch connector. 700 grams of refrigerant is roughly 1.54 lbs. I’d search this forum to find out if that’s the proper amount of R134a. The E46 AC system is sensitive to under and over-filling. Did you add any compressor oil?
Yeah i will check it in the weekend thats when i have time , i did not add oil
 

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A decent modern A/C machine should automatically add some oil to its R134A. Well, at least those I worked with. Except for the really old stuff where I did have to add a specific amount of oil.

If I can go slightly offtopic: I am not 100% sure about adding oil. IF you have a tiny leak, and after weeks your A/C system is empty, isn't it likely that the gas did evaporate, but the oil is still in there? If you add oil on top of refilling your system, wouldn't you have too much oil in your system?
 

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Discussion Starter #10
I found the probleme, the cable that gives power to the ac was disconnected , I plugged back in and it’s blowing very cold air , thanks everyone .
 
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