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Discussion Starter · #1 · (Edited)
Recharge Your 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... 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!

· Registered
7,259 Posts
Discussion Starter · #2 ·
From a Professional Source:

You can if you can get your hands on the correct type of refrigerant required for your vehicle. But that is now a major problem for do-it-yourselfers because federal law prohibits the sale of R12 and R134 automotive refrigerants to "noncertified" individuals (to become certified, you must pass a written test approved by the Environmental Protection Agency (EPA) -- something which all professional A/C technicians must do before they can legally work on your vehicle). This rule has been in effect since November 1992.

The law was passed to discourage people from recharging leaky A/C systems. R12 refrigerant, which is used in all vehicles built prior to 1993, is an ozone-depleting chemical. So its sale and use is strictly regulated by the EPA. What's more, production of R12 ends December 31, 1995. After that date, the only R12 that will be available will be that which has already been stockpiled or can be recovered and recycled from existing A/C systems. As the supply dwindles, motorists will be forced to have their A/C systems converted to the new "ozone-safe" R134a refrigerant (a job which may require replacing hoses and other parts depending on the application and model year).

Until late 1994, anyone could still buy refrigerant in large bulk containers. Because of the high cost of such containers, the EPA thought few do-it-yourselfers would buy refrigerant in bulk. But even that loophole has now been plugged. So unless you're a certified professional technician, you can't buy automotive refrigerant period.

This law does not, however, make it illegal to own or use R12 refrigerant. But it does make it very difficult for the average person to obtain it.

Some companies have responded to the "refrigerant shortage" by introducing refrigerant substitutes. Unless such a product is EPA approved, however, it should not be used in your vehicle. Many of these products are flammable, which could create a potentially deadly fire hazard if your A/C system were ruptured during an accident. There is also the problem of "cross-contamination." Federal law requires professional technicians to recover and recycle the old refrigerant in your A/C system when doing A/C repairs. If there's some other kind of refrigerant in your system, it can contaminate their recovery and recycling equipment.
Recharging The A/c System

CAUTION: The high side of the A/C system is under considerable pressure. If a can of refrigerant is connected to the high side service fitting, it may explode! The system must therefore be recharged by using the low side service fitting only. If you are not sure which fittings are which, do not attempt to recharge your air conditioner yourself. Wear eye protection and avoid direct contact with the refrigerant as it can cause frostbite on bare skin.

The basic recharging procedure goes as follows:

1. Identify the low side service fitting.

2. Determine the type of refrigerant required by the system. On most 1993 and older vehicles, this would be R12. On most 1994 and newer vehicles, it would be R134a.

CAUTION: R12 and R134a refrigerants are incompatible and must not be intermixed. Use the type of refrigerant required for your A/C system only. On most 1993 and newer vehicles, there's an identification decal or sticker that tells what kind of refrigerant is required. Also, the size and design of R134a and R12 service fittings are different to avoid cross-contamination.

3. Connect a can of refrigerant to a gauge set or recharging hose and valve set. Follow the equipment supplier's directions for making the connections.

4. Open the valve momentarily on the gauge set or hose to blow all air out of the line (this is necessary to keep from introducing air and moisture into your A/C system).

5. Connect the gauge set or hose to the low side A/C service fitting on the vehicle. This is usually located near the receiver/drier or accumulator, or suction side of the compressor.

6. CAUTION: Make sure the can of refrigerant is held in the upright position so only vapor enters the line. Do not tip the can sideways or upside down as doing so will allow liquid to enter the low pressure side of the A/C system (This may cause damage to the A/C compressor). Also, never heat the can to make it empty faster as doing so may cause the can to explode.

7. Start the engine and turn the A/C system on high. The compressor should be engaged or cycling on and off (it may be necessary to jump the compressor clutch directly to the battery if the system is extremely low on refrigerant to keep it engaged). Compressor suction will pull refrigerant vapor into the system and slowly empty the can. This can take up to 10 minutes or more, so don't be anxious.

8. When the can is empty, disconnect the charging hose from the service fitting. Use care when disconnecting the "empty" can from the gauge set or charging hose as it may contain some residual refrigerant.

9. Add additional cans of refrigerant as needed until the system is properly charged.

CAUTION: The most common mistake made by do-it-yourselfers is overcharging. Too much refrigerant can reduce cooling efficiency just the same as too little refrigerant. To work properly, the A/C system needs just the right amount. Always refer to the system capacity specs in a shop manual or other source to determine how much refrigerant is required. System capacities are specified in ounces. One can of refrigerant equals about 14 oz. Usually three to four cans is enough to fully recharge a typical passenger car A/C system that was empty. If the system is low, one or two cans of refrigerant are usually all that's required.
yes you can
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