Hi All,

I'm bumping this thread as I just replaced my compressor coil today and this thread was very helpful. Thank you for going through the effort to write this up! I have a couple of things to add based on my experience today:

• I just recently bought this R50, so I wasn't sure... but you don't need the proprietary tool to remove the serpentine belt. I just put a piece of pipe on my floor jack and pushed the tensioner upwards from the bottom.
• This project sucks! It wasn't terribly time consuming, but it could have been so much faster if there was better access to the compressor. I did remove the engine mount arm and pull the engine back and it was still extremely tight getting to the front two bolts. I am happy I won't have to do this again.
• I much prefer shopping on Amazon to Ebay, so I went there to buy my coil. There is a listing for just the coil, but from the reviews, it does not have the correct bore size so I would steer clear of that one. The one I bought came with the entire coil/pulley/clutch assembly.
• Mine had two wires like the ones posted about above. At first I thought that I would remove the second wire because I'm sure the coil grounds through the body like the factory one, but then I thought better... I DID NOT want to take this thing back apart again, so I played it safe. I put the ground wire under the T25 bolt that holds the coil connector to the compressor housing. It works perfectly this way, but I am unsure if it is necessary. Both the ground and the connector wire are longer than they need to be though.
• When I pulled my compressor out, I noticed that the pulley was able to spin freely. When I got everything back together, I noticed that the clutch and pulley were already engaged and the pulley would barely turn. The kit I bought came with two new shims -- I played around with it and ended up using the two original shims and one of the new ones. I have never pulled an AC compressor apart before, so I may not know what I'm doing here, but intuitively it really didn't make sense to me that the clutch would be engaged with the pulley right off the bat.
• Just a tip: Buy high quality snap ring pliers.
• When I got it back together and started up the car, it was still blowing hot air! I ran to the auto parts store really quick and picked up a can of R134a with a gauge attachment. I don't remember the exact pressure, but mine was at the low end of the green zone on the dial. I charged it up and it is blowing ice cold now.

Thanks again for the write up, it was very helpful. For anyone looking to do this job, just be sure to be patient. Nothing is particularly difficult, it just takes longer than it should and that can be frustrating. Now, on to the window regulator. Cheers.

 

I'm an original owner of a 2004 R53 currently at 71k miles. AC has never had issues but recently experienced the AC compressor coil failure. Lots of great info here (many thanks to all) to help diagnose and get the job done. Currently a replacement AC coil/pulley/clutch package is being sold on eBay for less than $40 which is pretty amazing. To try to add anything useful here based on my experience:

• Prior tip above to buy high quality snap ring pliers is a good one. In the very helpful video posted by Mod-Mini on this procedure, he recommended this lower cost tool for the job which I purchased, but I just had no luck with getting to work. He handled it like the pro he is, but for this rookie the pins kept bending and my fat fingers just could not make it work. Picked up a high quality pair at Home Depot (these)...seemed excessive at $30 but made it simple and was a night and day difference.
• The pulley did not come off easily for me. Took some WD-40, a rubber mallet and a little patience to get it off.
• As mentioned the kit I purchased off eBay came with coil/pulley/clutch - but ultimately I decided to only use the coil. The new pulley did not spin as easily...this may have just been due to it being new and the grease being tightly packed and not worn in...but spinning by hand it would spin one rotation...where the old one would keep smoothly spinning for more times than I could count. The old one just felt like way less resistance, was still smooth and made no noise. I was concerned the tolerances with the aftermarket part were not as good, so re-used all other parts (clip rings, pulley, clutch). Not sure if this was the best decision but I have the backup/new parts if something fails here.
• To do the job, I elected to put the car in front end service mode (removing bumper, etc.) since I'm familiar with the procedure and figured it would likely give me the most room for my hands to get the top bolts. Worked fine for me going this route - though likely significantly slower than using a strap to pull back the motor and shown by the original poster here (gknorr) and Mod-Mini.

 

Thanks to the OP and you as well maxp.

Subscribing as I'll be doing this soon....

 

The two bolts that hold the ac compressor on the top did break any ideas how to get these out ?

 

You'll probably need to drill out and re-tap the threads, so you'll need to remove the front bumper to get better access for the project. If you haven't removed the front bumper yet, a quick search on youtube will bring up a good how-to. It's not hard and has to be done for a lot of repairs, so it's a good thing to learn. Good luck!

 

The A/C in my 2005 Mini cooper S JCW recently began blowing hot air. No gradual transition from cold to hot air, just hot all one day. I checked all of the fuses and after reading a bunch of threads, I'm wondering if its the clutch coil. So if I test for resistance b/t pin 87 of the AC relay and ground and get an open circuit/OL, is it likely that the clutch coil is bad? Does it matter if the car is running? Thanks!

 

An open circuit does point to the clutch coil being bad. The wiring on the connector for the clutch coil on the compressor tends to deteriorate over many years, and does completely come apart sometimes, causing that open circuit. The car does not have to be running when you test the resistance. You can also do a visual check of the compressor pulley with the car running. When looking down from the front of the car, see if the AC pulley (the one with the three circles on it) spins when the AC button is pressed.

 

My Circlip that holds the coil onto the compressor was rusted and came off in pieces. Anyone know what size or have a source where to get a replacement?
Thanks,
Bill

 

Not sure of the size unfortunately. With a little luck, maybe this kit at Harbor Freight has one close enough to work:

https://www.harborfreight.com/300-pi...ent-67655.html

 

HI Guys

I was going to replace the ac compressor coil on my 2005 R53
After removing the center T30 Torx bolt, I made a real stupid mistake. Instead of removing the outer circlip, I removed both the outer and the small circlip inside the center shaft, which drained all the oil inside the compressor. I am really hoping it is the oil and not the refrigerant itself. Is there any way to refill it if so what kind of oil?

A picture of the compressor where the wrong Circlip opened is attached. The inner end of red marking is where the Circlip was

 

If refrigerant came out under pressure it would have been quite the show. There is a refill hole on the top more than likely. Mine is an r56, so I'm not positive. The parts store can tell you what PAG oil you need.

 

Hi Lex2008

Thanks for the reply! going to look around he compressor to see if there is a fill hole

fortunately, I wasn't there to witness the damage ( this just happened while I went for a break ), but a black washer shot out a feet away along with the oil or whatever it was. I was lucky it didn't happen on my face
If it is just oil, will be be under pressure?

 

Their would have been a lot of hissing and refrigerant and oil spitting everywhere.

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Agree, if this is refrigerant oil, you would have heard hissing, and the oil would have been spraying/spitting out, not just dripping. The system is under pressure, and is nothing like draining the engine oil.

Of course, that assumes the system had a normal charge and the only failed component is the AC clutch. If you're no-cold-air was due to refrigerant loss and the system didn't have any refrigerant left, then the oil would drip out. Did you verify the coil was bad? Did your AC gradually go warm, or suddenly?

When my compressor finally went out a few years ago and I installed a new one, I believe the PAG oil was added through the refrigerant line connections, with the compressor off the car. The instructions for the oil came with the new compressor, and surprisingly, I didn't see any specs in the Bentley for refrigerant oil in the AC compressor replacement section when checking tonight.

In a normal functioning system, a decent amount of the refrigerant oil is atomized in the refrigerant, and the professional AC evac and recharge systems account for this when you do an evac and recharge, measuring the oil removed and making sure the same amount is added back.

When replacing a components like the compressor or condenser, there are usually suggestions as to how much make up oil to add that come with the component. If you're pretty sure you've opened the system and lost a good amount of refrigerant oil and all the refrigerant, you will probably need to remove the compressor to completely drain it and refill with the correct amount of new PAG oil. I can try to do some searching to find the right amount, or someone here might know. If the system has been open for a while, it's also recommended to replace the drier. After the repairs are complete and the system is closed again, I'd recommend taking it to a shop so they can use their professional machine to put a vacuum on the system to clear any trace of moisture and then refill to the precise refrigerant amount.

 

I changed the AC compressor on my 2008 when I replaced the motor. I also replaced the drier, expansion valve and flushed the entire system. The new compressor had an unknown quantity of oil in it which caused me a lot of head scratching. Zero info in the instructions of the new compressor. Why they do this I dont know. These oil quantities are very very important. I ended up getting in touch with the manufacturer and after much pleading for info, it turns out they had already added all the oil the system needs to the compressor so I mistakenly doubled the amount of oil in the system which is why it wouldn't blow cold. I had to bring it to a shop twice to have them draw out oil. To this day the new AC doesnt blow cold enough. I really need to pull all the refrigerant, flush the lines, the condenser, the evaporator, change the drier. drain the compressor and start again. No thanks.

gknorr makes a great point. you need to account for how much PAG oil you've lost. Better to have a little too much (AC wont blow cold enough) than too little (compressor will seize).

 

Found the specs and guide for refrigerant oil for first gens. Really surprised the Bentley doesn't include these. See the attached PDFs.

 

Good info but you still never know how much is that new compressor unless the idiots who make them are kind enough to tell you.

 

That's why they have you drain and measure the new compressor's oil too. According to that doc, the amount they include in a new compressor is the full oil amount in the entire system, which unless you're replacing every component, will be too much. The minimum oil to include with a new compressor is 50mL, but if the old compressor had more, then you match to that amount and add another 10mL. I'm pretty sure my Delphi replacement compressor came with a sheet with these exact same instructions now that I've read them again.

 

This was 2 years ago now, but I think I tried draining first but virtually nothing came out. Clearly I did it incorrectly.

 

Lex2008 and gknorr, Thank you so much for the information and the pdf documents.
I've replaced engines and transmissions before, but never worked on the a/c systems. I am going to take this opportunity to learn the a/c system this time , as down time is not an issue anymore

Will post more questions as I get to the task. Thanks again!

 

Learn from my mistakes.... I have a thread on my ac issues and repair.

 

Happy to help and good luck with the repair!

 

I know - old thread... anyone know the bolt thread size on the A/C clutch bolt? Snapped mine off and need to drill it out and maybe re-tap - hopefully not and I will just need the bolt...

 

The guys from ECS Tuning might know....

 

Got it! Managed to drill cleanly into the bolt for a good 1/4", threaded in an extractor head, and out it came. Had a few extra bolts laying around from my recent rear suspension work and tried the closest looking size and it was perfect. The pitch of the A/C compressor clutch bolt if anyone else ever needs one is M6x1.0 and the length is 1.5 cm. I think there may even be space in there for a flange head bolt, so will check my local parts places tomorrow.