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E90/E91/E92/E93 (2006 - 2013)
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  #1  
Old 09-28-2011, 06:43 PM
BMWBrazil BMWBrazil is offline
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AC Freon Charge Port(low side)

HI there, I have been having problems with my A/C. Cool air o the driver side and HOT in the passanger side. I have ready it could be related to low freon.. I am trying to add a charge but i cant find the low side of the freon charge. Can anyone tell me where this is? a photo would be appreciated. thanks
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  #2  
Old 09-29-2011, 01:28 AM
GTOtoBMW GTOtoBMW is offline
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TAKE IT TO A SHOP!! This is not something you can do with a can of freon from the local auto parts store. You NEED to monitor both the high pressure and low pressure sides to enure a correct charge. Not only that, but mose of the cans on the shelf of the auto parts store include a bit of stop leak which can actually clog the system.
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Old 09-29-2011, 09:20 AM
BMWBrazil BMWBrazil is offline
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The shop near me wants to charge $254 for the freon.. I think this is a bit over priced. Hence the reason to find for a solution elsewhere
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  #4  
Old 09-29-2011, 09:54 AM
haskindm haskindm is offline
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Originally Posted by GTOtoBMW View Post
TAKE IT TO A SHOP!! This is not something you can do with a can of freon from the local auto parts store. You NEED to monitor both the high pressure and low pressure sides to enure a correct charge. Not only that, but mose of the cans on the shelf of the auto parts store include a bit of stop leak which can actually clog the system.
+1 This is not a do-it-yourself project! Too much freon is worse than too little! You could take a small problem and turn it into a MAJOR repair. Don't be "penny wise and pound foolish" get somebody that knows what they are doing to check the system.
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  #5  
Old 09-29-2011, 10:31 AM
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Zeichen311 Zeichen311 is offline
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Originally Posted by BMWBrazil View Post
The shop near me wants to charge $254 for the freon.. I think this is a bit over priced. Hence the reason to find for a solution elsewhere
Then get quotes from other shops. Without proper equipment you cannot recharge it yourself.

The A/C system needs to be charged with a precise amount of refrigerant, by weight--within +/-1 oz. The only way to determine the weight of refrigerant in the system is to start from zero. The system has to be completely evacuated then recharged. That's why it tends not to be a super-cheap operation.

The smart thing to do would be to bite the bullet and have the leak located and repaired as well. You do have a leak; refrigerant doesn't just go away or get used up over time. Otherwise you'll just be facing another evac/recharge bill before long.
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   N47 35' 30.13" E11 10' 33.36" - End of break-in...you can guess what came next. BMW CCA
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  #6  
Old 09-29-2011, 12:13 PM
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DSXMachina DSXMachina is offline
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Originally Posted by GTOtoBMW View Post
TAKE IT TO A SHOP!! This is not something you can do with a can of freon from the local auto parts store. You NEED to monitor both the high pressure and low pressure sides to enure a correct charge. Not only that, but mose of the cans on the shelf of the auto parts store include a bit of stop leak which can actually clog the system.
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Originally Posted by haskindm View Post
+1 This is not a do-it-yourself project! Too much freon is worse than too little! You could take a small problem and turn it into a MAJOR repair. Don't be "penny wise and pound foolish" get somebody that knows what they are doing to check the system.
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Originally Posted by Zeichen311 View Post
Then get quotes from other shops. Without proper equipment you cannot recharge it yourself.

The A/C system needs to be charged with a precise amount of refrigerant, by weight--within +/-1 oz. The only way to determine the weight of refrigerant in the system is to start from zero. The system has to be completely evacuated then recharged. That's why it tends not to be a super-cheap operation.

The smart thing to do would be to bite the bullet and have the leak located and repaired as well. You do have a leak; refrigerant doesn't just go away or get used up over time. Otherwise you'll just be facing another evac/recharge bill before long.
Don't listen to these guys! They are trying to put shops like mine out of business by preventing amateurs from damaging their AC systems! How can I take expensive European vacations if people stop recharging their own systems?
Your AC system has a specified charge of 590g. +or- 10 g. That translates to 20.8 oz. + or - 1/3 ounce! This is a critical charge. If you fall about 4 oz. below the spec you will get the problem you describe. If you 'add a can' of refrigerant you will be adding 12 ounces of liquid.
Now, assume your system has dropped to 16 oz. and you add 12 ounces. Now you have 28 ounces in there and you are 40% overcharged. Good-bye to a hose if you're lucky, a compressor if you're not.
Do you want to take that chance? I hope you do. I need the money, I'm going to Europe again next August.
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  #7  
Old 09-29-2011, 02:21 PM
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Zeichen311 Zeichen311 is offline
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Originally Posted by DSXMachina View Post
Don't listen to these guys! They are trying to put shops like mine out of business by preventing amateurs from damaging their AC systems! How can I take expensive European vacations if people stop recharging their own systems?

This is the key difference between the pros and us experienced amateurs--we often overlook critical consequences, like not funding DSX's "field research" into European machinery.

Curious, DSX: Why is the tolerance so much tighter now? Is it just because the total volume is lower, compressor design, both, neither, ... ?
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   N47 35' 30.13" E11 10' 33.36" - End of break-in...you can guess what came next. BMW CCA
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  #8  
Old 09-29-2011, 07:33 PM
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DSXMachina DSXMachina is offline
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Originally Posted by Zeichen311 View Post

This is the key difference between the pros and us experienced amateurs--we often overlook critical consequences, like not funding DSX's "field research" into European machinery.

Curious, DSX: Why is the tolerance so much tighter now? Is it just because the total volume is lower, compressor design, both, neither, ... ?
Simple answer distilled; legislation. As you know R-12 and many commercial refrigerants were found to be major contributors to ozone depletion back when that was the hot topic, i.e. before generic "global warming". Then it was found that R-12 and later its replacements (for instance R134a for automotive applications) were big carbon producers.
The Montreal Protocol was an agreement among developed nations to reduce the use of what became known as greenhouse gasses. At the time automotive refrigerant was R-12, known by the DuPont trade name "Freon". It's replacement is R134a which even though it is far better than R12 is still not as good as they wanted. So, the answer was to reduce the amount of R134a in each system. This was accomplished by running at higher pressures using more efficient condensers and evaporators. The downside is that unlike with R12 (Freon) there is no significant 'reserve' of refrigerant in the system, importantly there is not even room for a reserve. To obtain the needed efficiency each system must be charged to a much finer tolerance than in the old days (pre 1995).
Because there is no room for an excess, any overcharging results in overpressures (which equals overheat) and possible refrigerant slugging; liquid refrigerant entering the compressor.
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  #9  
Old 09-29-2011, 07:58 PM
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Zeichen311 Zeichen311 is offline
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Originally Posted by DSXMachina View Post
It's replacement is R134a which even though it is far better than R12 is still not as good as they wanted. So, the answer was to reduce the amount of R134a in each system. This was accomplished by running at higher pressures using more efficient condensers and evaporators.
That explains it. The difference between the E46-era system (2 lb +/- 1 oz, per Bentley, unless they're off which is possible as they don't cover recharging procedures) and the current one had me scratching my head, since both use R-134a. Thanks.

Sounds like yet another system whose components I can expect to not live as long as their predecessors.
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2011 335xi Individual 6MT - Azurite Black Metallic / Oyster & Black / Anthracite Maple + all the good stuff

   N47 35' 30.13" E11 10' 33.36" - End of break-in...you can guess what came next. BMW CCA

Last edited by Zeichen311; 09-29-2011 at 07:59 PM.
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  #10  
Old 09-29-2011, 08:05 PM
NOLA335 NOLA335 is offline
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Haven't had problems with my ac yet but, believe me, when I do I'll be out looking for the low side fill port. I charge the '98 Mercedes myself and have never had a problem. Key is to add just enough to eliminate the high temperature from the vent. Overcharging is a concern. That's true. Getting the right type of refrigerant is a must (R134a and not "freon"). But this is a DIY project with a little education and information. Shouldn't scare anyone with a little knowledge.
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  #11  
Old 09-29-2011, 08:11 PM
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DSXMachina DSXMachina is offline
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Originally Posted by Zeichen311 View Post
That explains it. The difference between the E46-era system (2 lb +/- 1 oz, per Bentley, unless they're off which is possible as they don't cover recharging procedures) and the current one had me scratching my head, since both use R-134a. Thanks.

Sounds like yet another system whose components I can expect to not live as long as their predecessors.
Now that we all have our fancy 134a equipment paid off the powers that be have decided that R134a is no longer good enough and have come up with a new refirigerant. Are you ready? No, I'm not making this up, the name of the new refrigerant is....R1234a! God help us all.
It runs at even higher pressures, requires new (unproven!) technologies and is replaced using all new handling equipment. It cannot be used to retrofit 'old' R134a systems like we used R134a to retrofit R12 systems. It is supposedly going to cost over $50 per pound unlike R134a which I pay roughly $4 a pound for. Refrigeration repair is going to become rocket science and what you're going to have is a lot of cars driving around in August with their windows down.
Still, HVAC work is the cash cow of my business and I expect it will become even more profitable for those who don't panic and bail out.
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  #12  
Old 09-29-2011, 08:20 PM
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DSXMachina DSXMachina is offline
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Originally Posted by NOLA335 View Post
Haven't had problems with my ac yet but, believe me, when I do I'll be out looking for the low side fill port. I charge the '98 Mercedes myself and have never had a problem. Key is to add just enough to eliminate the high temperature from the vent. Overcharging is a concern. That's true. Getting the right type of refrigerant is a must (R134a and not "freon"). But this is a DIY project with a little education and information. Shouldn't scare anyone with a little knowledge.
Gotta disagree. The OP's problem may not be due to loss of refrigerant. There are other faults which can result in similar conditions. Just one for instance; the condenser fan craps out. Then the condenser doesn't...condense, and more hot gas than liquid gets to the evaporator. Or how about the expansion valve has stuck open and the evap has iced up like a 1950's refrigerator and it can no longer cool the air passing through it.
If he adds a can of refrigerant under those conditions he could cause himself some very expensive problems. Which would be great if he lived around here.
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