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Heating and Air Conditioning :: Replacing the A/C Compressor Clutch Coil

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Old 07-04-2012, 09:48 PM
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Heating and Air Conditioning :: Replacing the A/C Compressor Clutch Coil

If you're A/C has gone warm, it could be due to a number of problems, but one of the common ones that seems to be popping up is a faulty A/C compressor clutch coil. My A/C died suddenly after accelerating up a hill, so it seemed very unlikely to be due to a low refrigerant issue.

Thankfully, replacing the A/C compressor clutch coil isn't too expensive or difficult to repair. Most shops will tell you the coil is not available alone and that you have to install a new compressor - a very costly repair. This is not true!

First, you should confirm that your A/C problem is the clutch coil. This can be done by testing the resistance of the coil from it's relay. The relay is located in the engine bay fuse box. Unplug the relay and test the resistance between the terminal for pin 87 and the negative terminal of the battery (see picture below for the wiring on the relay). If you don't get a relatively small reading, your problem is likely the A/C clutch coil. My new OEM clutch coil has a resistance of just over 25 ohms. The faulty coil had a resistance of over 51k ohms! A faulty coil may also simply cause a completely open circuit.



Second, check the front of the engine block for a build of road grime and oil. This could be a sign of a weeping crank position sensor o-ring, and you can get to it more easily during the clutch coil replacement - might as well consolidate repairs. The o-ring only leaks/weeps when the car is running so you won't see oil drops on your garage floor from it either. Mine had a lot of grime build up and I wish I had known beforehand so I could have consolidated repairs.

Assuming you've pinpointed your A/C problem to be a faulty compressor clutch coil, here's how to proceed. As always, any repairs you do are at your own risk, and I assume no responsibility for anything that might result from using these guidelines.

What you need:

- Jack, one Jack stand
- ratchet and 10mm, 13mm, and 16mm sockets
- T30 socket
- T25 socket or screwdriver
- Load strap
- Philips screwdriver
- Snap ring pliers
- Threadlocker (optional)
- New A/C compressor clutch coil or clutch coil with pulley (aftermarket coil alone was available on eBay at the time of writing this. OEM clutch coil w/ pulley is Delphi part #01650060, available from Rockauto, ships from Great Britain. The Delphi part is what I used and I recommend it, since you get an OEM coil with connector and a new pulley bearing too.) EDIT - as of 7/5/2012, both these sources no longer have the part available. Hopefully this is temporary! For now, your best/cheapest option is to go with an aftermarket one on eBay, Aliexpress, Amazon, etc.
- Serpentine belt wrench tool (there are other ways getting the belt off, at least on an R50 - see below).
- Medium Duty impact wrench (I used Harbor Freight item #67845)
- Box, or something else to support the A/C compressor once loosened.
- Optional - new serpentine belt if you haven't replaced yours in a while.

What to do:

1. Remove the connector on the negative terminal of the battery. Secure it from coming into contact with the battery. On an R50, I usually replace the battery cover after removing the connector.

2. Remove the serpentine belt. Here's a how-to for the R50. Here's one for the R53. I do not have the R50 serpentine belt tool, but instead use a long bar and jack to raise the tensioner from underneath. It's not ideal, but it does get the job done.

3. If you didn't remove it for the serpentine belt, remove the undercarriage protection. Three 10mm bolts under the front bumper and two philips screws further back on the subframe.




I also recommend removing the wheel well plastic protection, as it will allow you to see more, but it could be considered an unnecessary step by some. The wheel well plastic protection is removed by loosing a bunch of plastic philips screws and three metal philips screws. The plastic screws pop out when loosened.



4. Remove the lower engine mount. There are two 16mm bolts holding this in. Getting it out requires a little wiggling.



5. Re-insert the forward bolt for the engine mount and loop your load strap through it and attach the hooks to a secure point further back on the subframe. You can see where I attached mine. Now slowly tighten the load strap, gently easing the engine back a few inches. This will give you a little more room to loosen the A/C compressor bolts. (and get to the crank position sensor o-ring if you're doing that too)




The increased gap in front of the compressor - still pretty tight!


6. Now it's time to remove the A/C compressor. It is held in by three 13 mm bolts. Remove the forward two bolts first - they are above the compressor. It's still not much room to work with even with the engine pulled back, but there's just enough room to get a ratchet and hand in there. The third bolt is just underneath the A/C pulley.



The compressor has rubber mounts on the bottom, so you will still have to wiggle it out with all the bolts removed. Have something ready underneath to support the compressor once you have it out. Disconnect the electrical connector - it just slides out.

7. Remove the bracket for the electrical connector - it is a T25. Remember the little metal piece's orientation.




8. The bolt on the A/C pulley is a T30. This bolt appears to have some kind of threadlocker on it and is just about impossible to remove without an impact wrench. With an impact wrench, it comes out in under 5 seconds. Make sure you have an impact wrench! I used an electric medium duty one from Harbor Freight and it worked perfectly. The top piece on the pulley will now pull off - it will take a little wiggling. There are little shims in this piece - do not lose them! You will need to reuse them on the new one!

The bolt:


The impact wrench I used:


The shims:


Where they go:


9. The pulley itself is held in with a snap ring - expand the ring and remove it with your snap-ring pliers. Now the pulley will slide off.



Snap ring pliers:


10. The clutch coil is also held in with a snap ring - expand and remove.



11. Now install the new clutch coil and pulley. Don't forget to include the shims on the new pulley. For the bolt on the pulley, tighten by hand first, and then tighten it for a very short amount of time with the impact wrench. I also used some blue threadlocker on it, since it seemed to originally have some kind of threadlocker on it. Remount the connector bracket/connector and plug it in.



Compressor ready to be bolted back in:


12. There is a decent how-to for the crank position sensor o-ring replacement on motoring alliance if you're planning on doing that too. A quick search should lead you to it...

Tightening torques:

3 A/C Compressor bolts - 25 Nm (if you can even get a torque wrench on the two front ones!)
2 engine mount bolts - 100 Nm

13. After you have A/C compressor bolted back in and the serpentine belt on, connect the battery, turn it on, and test out your A/C. Hopefully it's nice and cold again!

14. I have seen suggestions to do a break-in procedure for the new clutch (only applies to those who got the Delphi part that includes a new pulley). It can supposedly help make the compressor clutch capable of a higher torque. Here's one such suggestion:

Cycle the compressor clutch approximately twenty times (five seconds on, then five seconds off). During this procedure, set the A/C control to the recirculation mode (Max-A/C), the blower motor switch in the highest speed position, and the engine speed at 1,500 to 2,000 rpm.

15. Although unnecessary, you might consider getting a refrigerant evac and recharge done afterwards, just to make sure the system is operating as efficiently as possible - it should reduce wear on your compressor over time. My MINI is nine years old and the A/C system has never been touched. Even under normal conditions, the system will lose trace amounts of refrigerant over many years (on average, 6-7% per year - I have a study on this - PM me if interested). Mine had about .5 lbs in before the recharge and is now up to the full .9 lbs (415 +/-10 grams) after the recharge. Admittedly, the actual cooling performance didn't change much, but I still feel good about it being up to full operating potential...

16. Enjoy the cool air!


For any interested, the old A/C clutch component certainly had plenty of usable life left. Here are some pics of it:




The wire on the old coil was also frayed, which contributed to the coil's failure. After dissecting the coil, there are a few additional components - a diode and a capacitor I think - one of these is probably the main point of failure.


 

Last edited by gknorr; 08-23-2018 at 09:01 AM. Reason: Relinked pictures.
  #2  
Old 07-06-2012, 07:05 AM
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I believe this part went out on me yesterday....Time to look for the clutch...

Could any other damage occur to the compressor or A/C or belt if this does go out.

Is the car still safe to drive if this goes out...

Sorry for the Noob ?'s but I do Computers not Car Engines
 
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Old 07-06-2012, 07:11 AM
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Originally Posted by nharrison21 View Post
I believe this part went out on me yesterday....Time to look for the clutch...

Could any other damage occur to the compressor or A/C or belt if this does go out.

Is the car still safe to drive if this goes out...

Sorry for the Noob ?'s but I do Computers not Car Engines
No worry for other damage and the car is perfectly safe to drive - when the clutch coil dies, it simply keeps the compressor off all the time.

If you haven't replaced your serpentine belt in a while, it could be a good time to put a new one on though - I'll add that note to the how-to
 
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Old 07-07-2012, 06:11 PM
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That make me feel a whole lot better about trying to drive it to a local shop to get it checked out at least to see if this is infact the faulty part or if the entire AC comp. went out on me...Now If this is infact the faulty part I just have to find it....
 
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Old 07-07-2012, 06:25 PM
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Originally Posted by nharrison21 View Post
That make me feel a whole lot better about trying to drive it to a local shop to get it checked out at least to see if this is infact the faulty part or if the entire AC comp. went out on me...Now If this is infact the faulty part I just have to find it....
Pretty easy to check on your own if you have a multimeter. If you don't have a multimeter, you could probably get one from Harbor Freight or Walmart for cheaper than a shop would charge for a diagnosis...

Did your A/C go warm suddenly while driving?
 
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Old 07-07-2012, 06:34 PM
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Yeah I was sitting at a light...heard a new/unfamiliar sound from under the bonnet....then white smoke......pulled over immediately to investigate and didnt see any life threatening problems so drove it a 1/2 mile home and noticed the A/C was now nothing but heat as it was 104 outside that day
 
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Old 07-07-2012, 07:04 PM
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Hmm...the unfamiliar sound and white smoke part seem a little alarming.

When mine went out, it was sudden, but the only symptom was no cold air immediately after accelerating up a hill.

Either way, still worth testing for the resistance between the terminal for pin 87 of the A/C Relay and ground - then you'll at least know whether or not the coil is dead. An auto parts store might even have a loaner or courtesy multimeter to use...
 
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Old 07-08-2012, 08:09 AM
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ok...so went out this morning and checked the resistance and got 45-123 as it was bouncing around...which I take it means that it is the AC compressor and not the coil
 
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Old 07-08-2012, 10:32 AM
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Originally Posted by nharrison21 View Post
ok...so went out this morning and checked the resistance and got 45-123 as it was bouncing around...which I take it means that it is the AC compressor and not the coil
That's a little high (probably due to some copper corrosion like what was on my wire), but my guess is the coil is not your problem. Given the sound and smoke, it does seem to point to the compressor.

If you end up getting the compressor replaced, try to keep the old clutch coil on the old compressor - you might be able to sell it or have it around just in case...
 
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Old 07-08-2012, 09:25 PM
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Great write up! Currently my air-cond seem blowing hot air randomly and if I lower the tempreature by 1 (ie: 22 to 21) than it start blowing cold air again... it been happening quite frequently.

I have bring to shop for service (re-charge the gas and change the dryier), it was ok during that time but now the same problem come back.

Do you think changing this part able to solve? Sorry I dont have multimeter to test sigh..
 
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Old 07-09-2012, 06:44 AM
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Originally Posted by vodka View Post
Great write up! Currently my air-cond seem blowing hot air randomly and if I lower the tempreature by 1 (ie: 22 to 21) than it start blowing cold air again... it been happening quite frequently.

I have bring to shop for service (re-charge the gas and change the dryier), it was ok during that time but now the same problem come back.

Do you think changing this part able to solve? Sorry I dont have multimeter to test sigh..
Since you're A/C is still turning on and getting cold, it's unlikely changing this part will solve your problem.

Was the system checked for leaks with the fluorescent dye? Hopefully you don't have a leak.

How hot out is it when the A/C randomly cycles on and off? I wonder if your problem is related to stage 1 on the cooling fan being out. Check out this thread:

https://www.northamericanmotoring.co...-solution.html
 
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Old 07-10-2012, 04:08 PM
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Well just heard from pep boys and they say I have this problem

https://www.northamericanmotoring.co...ng-issues.html


The hose blew out on me and since it is buried beyond belief that it is a 5+ hour job...ugh
 
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Old 07-10-2012, 05:51 PM
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Originally Posted by nharrison21 View Post
Well just heard from pep boys and they say I have this problem

https://www.northamericanmotoring.co...ng-issues.html


The hose blew out on me and since it is buried beyond belief that it is a 5+ hour job...ugh
Hmmm - crazy! I'll have to take a look at mine to make sure it's not rubbing on anything.

Part of me believes there's got to be a way to use some sort of coupling to replace the little part of the hose that's failed.

See if you can find a dedicated A/C shop, maybe not even necessarily an automotive A/C shop, and ask them if it's possible to replace just a small section of refrigerant hose...
 
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Old 07-27-2013, 05:56 AM
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Thank you

this thread was MASSIVELY helpful to me. the only thing that might make it better is to list where to get the cheapest parts!! my 04 R50 has made the noise since I bought it a year ago, and as I was driving home, ALL of the electrical systems started going crazy. (from what I assume is a very serious short in the ac compressor clutch coil) and I would also like to point out that instead of the factory tensioner tool I was able to use a basin wrench!!!
 
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Old 09-06-2013, 05:30 PM
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So mine just metered out at 30k ohms...I'm going to say that I found my problem

Off to ebay to order the part! Thanks for the great write up.
 
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Old 09-11-2013, 03:45 PM
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The symptom that my wife reported was that the air was abnormally cold. She turned the A/C off for three minutes and then turned it back on and it would no longer blow cold air. She also said it had been producing a mildew odor.

I took it to have it diagnosed (already feeling ripped off about that but I'll spare you the details) and they said it was the compressor. They would also replace the receiver drier if they did the repair.

Knowing that they don't want to replace just the clutch, I checked the resistance as stated in this article and I got a very low reading meaning it appears pin 87 was well grounded.

With this information, do you think I should attempt to replace just the clutch? Or should I have a shop replace the whole compressor?
 
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Old 09-11-2013, 05:14 PM
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Originally Posted by tim781996 View Post
The symptom that my wife reported was that the air was abnormally cold. She turned the A/C off for three minutes and then turned it back on and it would no longer blow cold air. She also said it had been producing a mildew odor.

I took it to have it diagnosed (already feeling ripped off about that but I'll spare you the details) and they said it was the compressor. They would also replace the receiver drier if they did the repair.

Knowing that they don't want to replace just the clutch, I checked the resistance as stated in this article and I got a very low reading meaning it appears pin 87 was well grounded.

With this information, do you think I should attempt to replace just the clutch? Or should I have a shop replace the whole compressor?
If you got a low resistance (should be 20-30 ohms), then the clutch is most likely okay. Sounds like it really is your compressor that went out.

My understanding is that the orifice tube/expansion valve and drier/accumulator need to be replaced when the compressor is replaced, and the whole system needs to be flushed. Apparently, the compressor can release debris into the system when it fails.
 
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Old 09-11-2013, 05:16 PM
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Also, I've been following this A/C compressor on Amazon - it's the same brand as the OEM one and is a great price:

Amazon.com: Delphi CS20066 New Air Conditioning Compressor: Automotive Amazon.com: Delphi CS20066 New Air Conditioning Compressor: Automotive

Update 5/2015 - wow, the price has gone up considerably! Still cheaper than OEM though...
 

Last edited by gknorr; 05-10-2015 at 07:35 PM.
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Old 09-11-2013, 05:18 PM
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Originally Posted by gknorr View Post
If you got a low resistance (should be 20-30 ohms), then the clutch is most likely okay. Sounds like it really is your compressor that went out.

My understanding is that the orifice tube/expansion valve and drier/accumulator need to be replaced when the compressor is replaced, and the whole system needs to be flushed. Apparently, the compressor can release debris into the system when it fails.
Thanks for the reply. It doesn't look like a job I'm capable of taking on. Now to see if I can find a shop in my area who can do it for less than $1616.
 
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Old 09-11-2013, 05:57 PM
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You might see if you can purchase the parts yourself and find a shop that will install for you. There's a good chance you'll save hundreds of dollars.

Get the Delphi compressor at Amazon, and the Delphi accumulator and expansion valve from Rockauto. All that will run you about $450 (half the cost of the compressor alone from MINI), and you should be able to find a shop that will do the work to bring the total to less than $1000 easily.

Best of luck!
 
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Old 09-11-2013, 06:10 PM
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Thanks for the suggestion. MINIs aren't very popular up here so I get nervous about bringing mine to folks who are probably doing the job for the first time.
 
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Old 09-11-2013, 06:12 PM
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You could try to find a reputable BMW shop too. Just make sure the shop has experience working on AC systems and you should (fingers crossed) be okay.
 
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Old 09-12-2013, 07:59 AM
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So I ordered the Delphi A/C compressor and the URO receiver drier from Amazon for $343. I always have mixed feelings about buying from Amazon, not because I'm worried about the quality, but because I can't understand how they can sell this stuff for 30%-50% less than every other site. I feel bad for not supporting other suppliers, but on the other hand I'm not flush with cash either.

Ethical dilemmas aside, I've got an experienced local mechanic who agreed to install the for me. So if all goes well, we'll have A/C again by Monday night.
 
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Old 09-12-2013, 08:16 AM
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Originally Posted by tim781996 View Post
So I ordered the Delphi A/C compressor and the URO receiver drier from Amazon for $343. I always have mixed feelings about buying from Amazon, not because I'm worried about the quality, but because I can't understand how they can sell this stuff for 30%-50% less than every other site. I feel bad for not supporting other suppliers, but on the other hand I'm not flush with cash either.

Ethical dilemmas aside, I've got an experienced local mechanic who agreed to install the for me. So if all goes well, we'll have A/C again by Monday night.
You should also pick up a new expansion valve too - otherwise a warranty claim on the compressor might be rejected.

http://www.rockauto.com/info/Delphi/...lish_11076.pdf

Hopefully you won't have to make a warranty claim on it, but just in case...
 
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Old 09-12-2013, 08:45 AM
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NAPA has one available locally so I'll go pick that up today rather than risk a shipping delay. Anything else?

BTW, thanks for all the help.
 

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