DIY: Replacing the AC Compressor

[licwid]

Hey Guys,

I am in the process of changing my AC compressor, and thought I'd try and document the process for others. I am using this as a placeholder for now, and also as a place to save my reference links.

Once I am done I will put together the steps and fill in any gaps that I can with pictures of the process.

Resources:
BMW Manual - http://bmw.workshop-manuals.com/1_Se...ex.php?id=2527
Torque Spec References - http://bmw.workshop-manuals.com/1_Se...ex.php?id=3491
Cowl, microfilter, and airbox removal - http://www.e90post.com/forums/showthread.php?t=654820
Charge pipe removal - http://www.activeautowerke.com/pdf/A...ff%20valve.pdf

Step 0: Have a shop evacuate your AC system and tell you how much oil you need to add back
Step 1: Prepare Cowl for Removal
1a: Unclip the 6 clips holding the wiring over the engine
- *Careful, these clips break easily (just ask the tech who broke 2 while doing work on my car.)
1b: Remove the 6 8mm bolts holding on the Pollen Micro Filter, and remove the filter and housing.
1c: Remove the 2 rubber tabs (1 on each cover) holding the ECU/ABS covers on.
1d: Unclip the plastic covers and remove them. (2 clips on each cover)


Step 2: Cowl Removal
2a: Remove the 2 8mm bolts securing the cowl
2b: Remove the two electrical clips, and unhook the wiring from the cowl (just pull up on the clips)
2c: Remove the 2 rubber tabs. 1 on each side of the cowl
2d: Lift up on the cowl, then pull it out towards the front of the car



Step 3: Remove the Airbox
remove vacuum fitting (squeeze it off) and unhook the hose

Remove front hose clamp with a flathead screwdriver
unclip snorkel/scoops from airbox

unhook (pull up) 3 rubber wire holders on the back of the airbox
Unscrew the hose clamp (already undone in the photo, sorry)

pull up on airbox. it is held on by 3 rubber grommets

Step 4: Remove Air Intake Scoops
4 torx bolts


Step 5: Remove chargepipe
disconnect diverter valves (slide/twist the grey clips clockwise and the valves then just slide off). I hung these out of the way instead of disconnecting the vacuum line.
use a flathead screwdriver and pull up on the raised part of the metal clip holding the pipe to the throttle body
remove hose clamp on other end of charge pipe (flathead screwdriver)
Remove the torx bolt securing the chargepipe
unclip sensor wiring near the back of the throttle body (squeeze)



Step 6: Remove Radiator fan
remove 1 torx bolt on the top of the passenger's side
unclip (squeeze) wiring harness on driver's side (top)
unclip the wiring harness from the top of the radiator
unhook clip near top/middle of the fan bracket on the driver's side
unclip FMIC charge piping from radiator fan bracket
unclip coolant hose on top of the fan bracket
lift up very carefully

Step 7: Loosen intake piping for more space to work
remove 2 torx bolts holding the front turbo intake pipe to the block


Step 8: Loosen coolant/AC lines for more space
remove the coolant lines around the compressor from their holder's/clips to allow flexibility of the lines
Unclipped the AC hose that runs in front of the engine to allow more room for removing the compressor through the top of the engine

Step 9: Remove serpentine belt
make note of the belt routing
Insert the T60 wrench into the tensioner pulley and apply pressure to loosen the tension on the belt
Slide the belt off the pulley and ease off the pressure on the tensioner pulley


Step 10: Compressor Removal final prep
Remove wiring clip from AC compressor (squeeze)
remove the 2 torx bolts holding the coolant lines from their holder's/clips


Step 11: Loosen 3 13mm bolts holding in AC Compressor
One is hard to get to as you cannot see it from the top. It is directly below the top bolt on the front, and the same size. You can find and loosen it by feel. I was not able to remove the bolt from the hole entirely until I removed the compressor (I was able to loosen in 100% however.)

Step 12: Remove the AC Compressor
The bolt holes for the compressor actually sit on a little lip, so you will have to pull the compressor up about 1/4" to get it off this lip. Then you can free remove it.
Once the compressor was off of the lip, I moved it to the front of the engine, and pulled it up between the engine and the radiator to remove it from the engine bay.

Step 13: Replace the Drier
It is cheap, so why not do it now too.

Step 14: Start with step 12 and work your way backwards to install everything

Step 15: Put a pump on the A/C for at least 1 hour, then charge the AC

[licwid]

reserved just in case

[Pablito1702]

Other than the compressor, what parts did you replace (serpetine belt, belt tensioner, etc.) Also where did you find the best prices for these parts? Thanks

[RimasRS]

Thank you. i need to do same thing. Was looking fir diy

[RimasRS]

One more question... Anybody know where AC pressure sensor/switch is located?

[an3ony]

resurrecting an ancient thread, has anybody with an N55 done this? My compressor is weeping oil and this repair will be in my future

[BMWFERN]

Originally Posted by an3ony

resurrecting an ancient thread, has anybody with an N55 done this? My compressor is weeping oil and this repair will be in my future

Mine just disintegrated today actually, I second the question if anyone has ever done this on a N55!