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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 03-16-2009, 12:22 PM   #1
Rene325ci
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Talking A/C Recharge 56k beware

This is a DIY for recharging your A/C System. The vehicle being used is mine it is a 2002 325ci. I have a leak somewhere in the A/C system (have not diagnosed it yet) and have run low on Freon. I am going to show how to recharge and how to read the gauges. This is a very basic DIY, but should be able to help you diagnose low Freon on your system. I am skipping some of the steps in order to explain and illustrate what it takes.

Steps I am skipping (since I still had Freon in system). I did not recover any of the Freon in the system. I did not vacuum the system after a recovery since I did not do a recovery. I did nothing more then a top-off of the Freon in the A/C system.

I know these pictures are kind of large, but i wanted people to be able to read them.

Freon: R-134a (what our cars use)
Gauges: Blue is low side, Red is high side, Yellow fill hose
Temp Gauge: Infra Red Temperature gauge

First picture is of the car off and gauges hooked up notice equal pressure on gauges. This is normal they should be equal.


This here is a picture of the hoses connected to the High and Low Side on the M-54 motor. They are different sizes so only one-way to put them on. Make sure no hoses are near the belts or fans.


This third photo is the temperature outside according to car.


Third picture is the Engine Running gauges reading pressure amounts. Compressor is functioning. Notice the pressure numbers @30 low side @140 high side.


This is an interesting pair of pictures of temperature at left and right center vent (A/C set at 59)
I have seen people talk about right hot, left cold. Oddly enough, it seems that when the BMW A/C is low on Freon it does this. The reason for this I do not know, could be heater core and evaporator position, but cannot say for sure.


This is a picture after I recharged the system of the gauge pressures. I used less then one (13 oz) can of R-134a to fill my system back up. You can tell that the pressure is now higher while the system is running. At the bottom of this DIY I have placed a how to fill A/C. Step by Step.


Here is another pair of pictures of the temperature after the refill. Notice the difference.


The right is still a little warmer, do not understand it, but I have A/C now.


STEPS FOR A REFILL.

1) Connect Gauges and read them.
2) Verify interior temperature as being warm and that low and high numbers are low (outside temperature can make a pressure difference; it was 80 degrees when I did mine.)
3) Connect new Freon can to the fill hose (puncture the can according to gauge instructions)
4) With engine running open fill valve
5) Fill only thru the low side (trust me only way it can be done, unless you like blowing things up)
6) Do small amounts at a time (overfill bad) watch the pressure numbers and check temperature coming out of vents in car. When you reach desired temperature, you can stop filling. More Freon then is needed will degrade the working efficiency of the A/C system or damage it.
Reminders:
1) BMW uses r-134a Freon (all E-46, older cars used r-12)
2) System (325ci) holds 1.63 lbs of Freon total.
3) I cannot be held responsible for your use of this information or any damage that you may cause to your system from doing this improperly. This work needs to be done by a trained technician (I am MACS certified)
4) This is also more of a guideline on how to do it.
5) All of these tools can be purchased through our fine sponsors as well as local shops.

I hope this helps and if their something you feel I should include or say about this please PM me and I will add it. I know a few people here are Techs and can give me more info and I am always willing to add it in and give proper credit to those that give me more information. Good luck and it is nice to have A/C again.

I will write up a diagnosis DIY eventually (when I have time to do it) and explain how to find the leak and what tools you can use to do that.

Sincerely,
Rene
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Old 03-16-2009, 02:27 PM   #2
Rene325ci
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no comments?
Should i even make anymore of these?
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Old 03-16-2009, 02:40 PM   #3
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i could use this .. where did u get that compressor thing? rent it or bought?
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Old 03-16-2009, 03:43 PM   #4
Rene325ci
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If you are talking about the gauges i bought them years ago (hence why they look so beat up) and you can get them at your local auto parts store.
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Old 03-17-2009, 07:59 PM   #5
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really nice write-up, will be looking forward to the leak diagnoses from you
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Old 03-18-2009, 07:56 AM   #6
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Thanks for sharing your knowledge.

Could you please tell us more about when to stop filling?
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Old 03-18-2009, 09:06 AM   #7
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I thought i had. Oh well no big deal. When i do a fill by gauges only i tend to open the low side fill valve for a few seconds and then close it. I then read the numbers. In normal Florida weather (about 80 Degrees) the gauges read like you see on the pictures at the end. I may have been able to put some more, but the numbers looked good to me so i left it alone. I don't know what the numbers are that BMW/NA recommends for the gauges (don't own a Bentley manual) to show they are perfect so i use personal knowledge and experience as my guide.

I may have to do a write up about how the A/C system in our cars work.
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Old 03-18-2009, 10:02 AM   #8
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Thanks for sharing, bro!

My AC is blowing warm right now and I need to get it taken care of before it gets stupid hot here.

I'm going to see if I can pick up the hardware at harborfreight and freon at Autozone today.
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Old 03-18-2009, 10:05 AM   #9
Rene325ci
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I am glad it helps out. If you can, buy one of the cans that comes with U/V dye in it. That way if you want to help find your leak when it goes warm again that Dye can help you. You will need to buy a U/V light to see the dye. I really need to do that diagnose thread.
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Old 03-18-2009, 10:08 AM   #10
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nice...i had a leak to last summer...i used that freon with the leak detector dye...its was a green color...it was able to spot the leak which was on the AC hose near the belts.
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Old 03-18-2009, 02:02 PM   #11
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nice...i had a leak to last summer...i used that freon with the leak detector dye...its was a green color...it was able to spot the leak which was on the AC hose near the belts.
Got to love when it is that easy. hope you changed the o-rings when you did the hose. Yeah saw a guy swap out a hose once and reuse the o-rings. Then ask "why do i still have a leak?"
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Old 03-18-2009, 02:36 PM   #12
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LOL..yeah i replaced the o-ring
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Got to love when it is that easy. hope you changed the o-rings when you did the hose. Yeah saw a guy swap out a hose once and reuse the o-rings. Then ask "why do i still have a leak?"
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Old 03-21-2009, 06:58 PM   #13
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Quote:
Originally Posted by Rene325ci View Post
I thought i had. Oh well no big deal. When i do a fill by gauges only i tend to open the low side fill valve for a few seconds and then close it. I then read the numbers. In normal Florida weather (about 80 Degrees) the gauges read like you see on the pictures at the end. I may have been able to put some more, but the numbers looked good to me so i left it alone. I don't know what the numbers are that BMW/NA recommends for the gauges (don't own a Bentley manual) to show they are perfect so i use personal knowledge and experience as my guide.

I may have to do a write up about how the A/C system in our cars work.
Very interesting write-up. Concerned about the numbers, I checked my Bentley and it did not give instructions about filling, only the capacity. It seems to me the appropriate pressures should be published in a table somewhere according to ambient conditions (temperature, pressure) and the refrigerant used (like the famous Carrier tables from thermodynamics class).

The capacity listed is
740 grams +/- 25 grams
2 lb +/- 1 oz
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Old 03-21-2009, 07:10 PM   #14
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The reason you cant find instruction for filling is because ac pressures directly relate to outside temp along with humidity. So there is no set reading that the low or high side pressure should read. There is a chart you can find that will help show what the readings should be close to.
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Old 03-21-2009, 07:20 PM   #15
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The reason you cant find instruction for filling is because ac pressures directly relate to outside temp along with humidity. So there is no set reading that the low or high side pressure should read. There is a chart you can find that will help show what the readings should be close to.
Thanks, that is what I suspected. Separately I found such a chart in another auto forum. However in the course of looking for this I found the following EPA legal notice at

http://www.epatest.com/609/

It would seem that, legally, this is not a DIY job for the typical shade tree mechanic in the US. There is training required, which can be done online, but also, my understanding, a requirement that there be recovery equipment on the job site.

THE EPA REGULATIONS
Since January 1, 1993, any person, repairing or servicing motor vehicle air conditioners shall certify, to the EPA that such person has acquired, and is properly using, approved equipment, and that each individual authorized to use the equipment is properly trained and certified under Section 609 of the Clean Air Act. In addition, only Section 609 Certified Motor Vehicle A/C technicians can purchase refrigerants in any size container from an auto supply house for use in cooling the passenger compartment of vehicles, including containers of 20 pounds or less.

Section 609 Certification allows the purchase of any refrigerant in any size container from an auto supply house for use in cooling the passenger compartment of vehicles!
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Old 03-21-2009, 09:31 PM   #16
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i need to do this, i havent had a/c in 2 years i only really need it maybe 5 days out of the year but still..
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Old 03-22-2009, 12:10 AM   #17
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I had the same problem until i got the whole core replaced. It was awhile ago, but I remember he said something about replacing some hose that is known to fail too. It was cheap, so I did not care about that part. I use to have to do the whole refilling the system thing all the time and the sides were different temperatures too. Now both sides are the same, or at least pretty close. I haven't taken the temp so I cant say for sure. Good write up too!
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Old 03-22-2009, 01:43 PM   #18
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The epa thing was created back when R-12 was the main refrigerant for auto and it is known to cause the ozone layer depletion. R-134a supposedly does not do this. One of the reasons it is illegal to do is because people would dump this freon into the environment instead of recovering it with the proper machine. Machine can cost anywhere from 800 to a couple thousand U.S.. The only time i need a machine is if i am doing a full vacuum of the system. I am lucky I have a budy who lets me do work at his shop so when i do a/c part replacement on my car i can do vacuum and recharge with his machine.
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Old 04-11-2009, 09:19 PM   #19
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Nuts quick update i found my leak. The evaporator died. I was going to do a write up on how to identify and find an A/C freon leak, but i found mine quite easily. I turned the car on and got a blast of a/c freon in the face (smell). I am going to have to find myself an evaporator, drier, and expansion valve. I am so dreading the dashboard removal hate taking those damn things out of a car.
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Old 04-12-2009, 10:25 PM   #20
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Thanks for the DIY! Very useful and informational.
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