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22 Posts
Sorry to bring up a old thread but I have a problem with my air conditioning/heater that I can't figure out. I have a 2001 325i automatic and the issue is my a/c blows as well as my heater but I'm not getting cold air on the AC and no hot air on the heater. I have read the above posts and have turned the dials to which ever one I'm using, blue for AC and red dots for the heater but nothing! Please help guys!

· Registered
6 Posts
Hot Air Balloon

Troubleshoot and Recharge Your BMW E46 Air Conditioning AC System In 3 Minutes for less than $20


Okay. So it is officially Summer here in the North East and that means two things: It is also Summer across most of the planet (except South America , South Africa & Australia) and the forums will get inundated with tons of My AC System Is Not Working threads!

Surprisingly there have not been a solid DIY for this yet (at least a DIY that could be found with a search in a the DIY Section) hence the weekly threads about AC blowing hot air on passenger side or hot air all around.

This DIY is for those folks with cars that DO NOT have major AC issues. Last year May on the first hot day of the year I noticed my AC vents were ONLY blowing cold air on the driver's side and hot or warm air out the passenger vents.

It's 80F+ Degrees out...

And your AC is on at full blast setting but...

...no Ice Cold Air is coming thru the vents :(

PART ONE: 1-3 Minute Troubleshoot

The forum DIY section didn't offer much help and I didn't want to spend my entire Income Tax Return check at the dealership. Luckily for me my friend who lives down south and owns a 2004 325i told me what was up and what I need to do.

On some E46 cars apparently the system can leak a bit of charge over the winter months when the AC system is not used for long stretches of time. You usually won't notice until the first hot day of the following spring/summer season and upon turning on your AC you realized there is cold air (or only cool air) ONLY blowing out at the driver's vents and hot or warm air streaming out the passenger vents.

Your first response is to assume the entire system is broken and something big and really expensive needs to be replaced. If you are a forum member you start one of many threads concerning vents blowing hot air or AC only blowing warm-cool air from the vents.

If your car has similar symptoms, before starting a thread or taking your car to the shop you should try this very quick, easy to do and cheap DIY to see if it will fix your AC ailments.

But even before you try my DIY make sure your center vent dial is set on the blue dots for cold air. I know it seems obvious, but lots of people overlook this simple function on the E46 and other similar BMW cars since the settings are not electronically indicated on the Climate Control Read Out Display.

In fact, you can have your Climate Control set to blow cold air (or even hot air during the winter months), but the setting on this dial takes precedence and the air coming out the vents WILL ALWAYS match what the dial is set on whether it be red dots to blow hot air or blue dots to blow cool air.

Other troubleshoot areas can be the AC Belts. Make sure you have them on your car and they are not shredded or loose. Also the AC Compressor which sits under the engine block may have been susceptible to oil leakage from a bad valve cover gasket, corrosive coolant fluid leaking from a broken hose, and/or washer fluid from a broken washer fluid tank pump (all which sits directly above this expensive to replace compressor).

So check for all these things. Worse case scenario the compressor is bad and you can either pay a ludicrous amount of money ($1,500 to $2,800) to replace it or for less than that you pack your stuff up and relocate to Beaver Creek, Yukon and hang out with my friend Jeb...

PART TWO: Recharge Your BMW AC System

Once that is taken care of and your car is still not expelling ICE COLD air then go down to Auto Zone, Pep Boys, Walmart or any sizable local Gas Station or Auto Store and spend $15 to $30 on a can of R134a freon. If this is your first can you will NEED to get a kit that comes with the indicator gauge. Generally it is cheaper to buy the can that comes with a gauge attached than buying gauge and can separate. Also most likely the gauge will be reusable so next can you buy in the future you will spend less as you will only need the can alone and that costs as little as $9.00 in some places. Also if your friend or neighbor has a gauge already feel free to borrow theirs and just buy the can alone.

Here is my big blue can of 134a + (NOTE: this size lasted me two years or two recharges to my car's system)

I don't understand the difference between the technology in my fancy looking $30 can and the cheaper plain looking $10 cans without the tech jargon littered all over the can.
But I just got the can that boasted the most on the label since this was my first time recharging my AC system I wanted it to be perfect.

My can also came with a gauge that was reusable.

And a nice bright and color coded gauge and a nice clear chart perfect for the someone that never done this before. Like I said, this DIY is already in itself so easy it is hard to mess it up and with a can like this it should be a piece of cake.

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!
I'm going to get a can soon... and check back with the forum. Very informative! Thanks!

· Premium Member
2021 Lexus ES300h Premium
29,650 Posts
You guys should figure out why your refrigerant was low to begin with before band-aiding it. I'd recommend taking it to a competent a/c shop who will test for leaks, identify the leak, then charge your system properly with professional equipment. Otherwise you'll just be chasing your tail. And wasting money.

· Registered
22 Posts
You guys should figure out why your refrigerant was low to begin with before band-aiding it. I'd recommend taking it to a competent a/c shop who will test for leaks, identify the leak, then charge your system properly with professional equipment. Otherwise you'll just be chasing your tail. And wasting money.

Very true Mango, I'm in the same situation and I'm done trying to chase it down myself, time to take it to a professional.

· Registered
431 Posts
You guys should figure out why your refrigerant was low to begin with before band-aiding it. I'd recommend taking it to a competent a/c shop who will test for leaks, identify the leak, then charge your system properly with professional equipment. Otherwise you'll just be chasing your tail. And wasting money.

NO ONE seems to understand that if you need to add freon, YOU HAVE A LEAK. many people think 'it just needs to be charged', like adding oil or gasoline.

mine makes a hissing noise when I turn it on; I'm going to need a professional to diagnose it.
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