Now for the Recharge DIY:
before you begin make sure your car is on, your engine is on and your Climate Control is on full blast set for the AC Cold Air Air Conditioner.
Next Go under your hood and find this small cap between the + battery terminal and Air Filter Box.
On European/Canadian/Asian models that have batteries under the hood it will be the port closest to the windshield.
There is a similar looking cap/port that sits at the front end of the bay between the washer fluid tank and head lamp housing. This is NOT the port you want so leave it alone.
And I will post a picture of it here so no one makes the mistake of touching it.
Now return to your correct port...
And begin unscrewing it. It shouldn't be too tight.
Once the cap is off you will see this. This port will give your gauge a reading of what the current pressure is in the system and will accept a charge to the system when R134a is applied.
Get your Can of R134a ready. My can had a gauge with a safety locking nozzle to prevent any mishaps during the recharge. This locking nozzle is also beneficial because you may have to shake the can whiles squeezing the trigger to apply the freon and you don't want anything to leak out during the process.
Now this is the only tricky part and here is where the gauge is super helpful. Now you do not want to overcharge the system because that would be WORSE than having a low charge. So make sure you read what your current psi is before you begin charging so you get an idea of what amount you may need to apply.
On my color coded gauge my system showed that it was filled and in the blue zone but on the lower end of the blue range. This is IMPORTANT to note because other gauges using only psi numbers may tell you that your system is full leading you to think that the problem is more deeper or elsewhere.
But make sure your system is not just filled to the lower range of full but towards the upper range before you move on.
At low blue my car was blowing cool air on the drivers vent and warm-hot air on the passenger side. At mid to upper blue my car was blowing ICE COLD air on all vents.
This lead me to believe that the AC System in our BMW cars are very sensitive to slight changes in the psi of the charge system and also our cars perhaps requires a tad more refrigerant than other cars need to produce ICE COLD air.
So once your system is fully charged and NOT OVERCHARGED you can un-hook the Can and gauge from your port, close the cap back onto the port opening and return to your cabin. If all is well with your system and there is no deeper inherent problems you will immediately feel the ICE COLD air blowing in some cases even before you get back into the car from under the hood it will be already cold in the cabin.
Sadly, our E46 BMW 3 series does not have the coveted MAX AC button on the Climate Control but once the temp is set to 59 F with the air output on high...
And the Snowflake is lit...
Then you will have MAX AC. ENJOY!