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Old 07-02-2012, 08:35 AM
apomerans apomerans is offline
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Location: Dallas, tx
Join Date: Jan 2012
Posts: 16
Mein Auto: 2005 745i
E65 AC compressor DIY

Preface - if you think this writeup is long - get a quote from BMW dealer on replacing ac compressor. After you get that number this DIY will rhyme as you read it, and you may feel compelled to turn it into a song

I'm NOT a mechanic, and I have replaced my AC compressor on e65 745i yesterday. Since I've found no DIY's for this, so I had to figure things out as I went.
I'm posting this so some other poor soul who wants to do it himself can fair better than I did.

Mechanically my experience before this is Changing brakes, replacing waterpump, water valve and expansion valve.
On Difficulty Scale of 1-10 where 1 is Replacing a Dome light bulb and 10 rebuilding an engine, for me this was a 5.

(Remember, you'll need metric sizes)

Obviously you'll need tools, so In this list I'm only going to list Critical ones, meaning I had to drive to Autozone 3 times to get this, otherwise
you cannot get any further.

- Extension for the wrench, long one, one not so long... At times I had to use both together to get reach
- Offset wrench 13mm
- Swivel socket adapter
- 27mm socket
- 6mm Allen bit.
- PAG ISO 46 Refrigerant oil
- Ramp (highly recommend vs having you car just jacked up)
- Rubber gloves
- Goggles

0. BEFORE you do this, be absolutely sure you know what the problem is, and the AC compressor is what you want to replace! I thought I knew things, before I took
an arrow in the knee (lol). Meaning I replaced Water valve - did not solve my issue, then expansion valve - no result. Then paid $136 at some shop to examine my
ac system and they told me it was compressor.

Here we go:

0. You need to get the Freon gas (134 thing) out of AC. You can take it to the shop, and they will draw the gas out for you. Or you can vent it into air yourself
through LOW side connection, and then from HIGH side connection. This option is illegal though. If you go option B have a fan blowing at you and wear rubber gloves,
you don't want to breathe this stuff. Drain SLOWLY not to agitate the oil. You can only guess which way I went.

1. Then I got front of car on ramp (Autozone, $50). This might get lengthy so I didn't trust the car jack with my life. Put something behind rear tires.
Then activate Magnetic Parking brake.

2. Open hood. Remove center and right side black covers.

3. You will need to remove AIR FILTER housing. Unscrew top of housing from the air pipe that goes to engine (2 star bolts), disconnect some other air pipe that's
connected to top of air filter and remove the housing top with filter. Now remove the bottom air filter bucket. Its only held by 2 smaller star screws in the front
Wiggle that bucket out

4. Get under car and remove splash shield under engine - black plastic cover.

5. Disconnect ac compressor wire from plug

6. Now you'll need to disconnect 2 hoses from AC compressor. Done from top (under the hood). Both are secured by bolts, 6mm hex. Space it tight! I took a wrench,
attached short (3 inch extension), then long (7 inch extension), then swivel socket adapter, and at the end 6mm hex bit. This gives you reach and flexibility
and torque. Remove bolts that hold both hoses, and pull hoses away. Now I would plug the two holes with something. I used paper towel pieces. This will prevent
refrigerant oil dripping on you when you wiggle compressor our from the bottom.

7. Get under car. You will need to lower stabilization bar first. Its held by 4 bolts 16mm, 2 on each side. There is also a cluster of hoses held by 1 bolt that
you will need to disconnect to give you more space. Secure stabilization bar with something, I tied it with wire next to one of the control arms so it would
not be all up in my face.

8. Now here comes the annoying part - removing the compressor. Wear goggles, so dust, or ref oil would not drip in your eyeball. Keep children away, as you may feel
the need to swear as needed to alleviate frustrations if they come.
a. Look at the compressor that YOU WILL INSTALL (not the one in the car). Look and understand where and how it connects by bolts. There are 3 long bolts
that need to be unscrewed. 2 in the front of comp (top and bottom) and one in the back. All bolts are 13mm

b. Remove front bottom bolt. I used wrench, extension, swivel socket, + 13mm
c. Remove front top bolt. I used more extensions swivel socket, + 13mm
d. Remove back bolt. Due to space and room to wiggle this may get difficult. No way to explain wiggling, figure it out yourself. Viewing From under the car,
in the back of compressor you will see a bolt. I used an offset 13mm wrench. Once removed you will realize its not a bolt, but a nut. Once nut is removed you
will see another bolt behind it. That's the one that holds the compressor. I used 13mm offset wrench to at least nudge it from "stuck" state, then
used wrench with 2 extensions + swivel socket + 13mm head.
e. Once back bolt is removed you can pull AC belt with your hands off
f. From under the car shuffling cables around take out AC compressor . NOTE: try to keep the hose holes from facing downward so that ref oil will not drip out
if your paper plug unplugs, and drips on you.

9. Once compressor is out take a cup ( you will never drink from it again) and pour oil out of compressor hose hole into cup, make sure nothing is spilled. Bang compressor
on the floor and try draining again, do it couple of times as oil permeates to the bottom of compressor hose holes from whatever is inside it.

10. Make a mark of the amount of oil that was taken out.

Now in reverse:

11. put comp back same way you've taken it out
12. Secure with 3 bolts
13. Attach stabilizer bar back
14. Attach hose cluster back

15. Take old oil in the cup and dispose of properly. Put same amount of new PAG 46 ref oil in same cup + a little tad more , use cone to pour that oil into ac compressor
hose hole that's at 45 degrees incline.

15. Attach AC hose to compressor that connects at 90 degrees
16. Attach the other hose that's at 45
17. Connect ac comp wire to ac wire connection

18. Put ac belt back on the compressor pulley. I Used 27mm socket to turn main dampener pulley (big one with 2 grove tracks) as I forced the ac belt back on
19. Attach back air bottom bucket, to air cover and connect to air pipe.

20. I should have taken the car to shop and have them treat AC system to get moisture out and create vacuum. I did not. I just attached Autozone 134 freon gas and filled
ac system that evening. It worked and now i have cold air again. DISCLAIMER - Because i didn't do that vaac and moisture thing - i dont know what may happen.
So far everything works. An auto shop guy told me that it may create hydrochloric acid if you dont get moisture out. Another guy told me - "Nay", I filled my benz 600
without doing vaac/moisture thing - its been 2 years - no problems. So I went with plan b. Plus I rationalized that its TX, 100 degree heat - what moisture?

I will update this post if this was a mistake.

You know how to do this whole thing better? POST here, other will appreciate your input.
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Last edited by apomerans; 07-02-2012 at 08:46 AM.
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Old 07-02-2012, 12:16 PM
apomerans apomerans is offline
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Location: Dallas, tx
Join Date: Jan 2012
Posts: 16
Mein Auto: 2005 745i
FOLLOWUP on the last disclaimer:

Today went to pep-boys to get more 134 refrigerant. Apperrantly they come with all sorts of additives like dye, leak sealing agents, etc... To my luck there was one that also "REMOVES MOISTURE" and "neutralizes ACID". Obviously I bought it.
So that removes almost all the risk of filling your system at home.
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Old 10-28-2012, 05:38 PM
flash_n flash_n is offline
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Location: Connecticut
Join Date: May 2012
Posts: 101
Mein Auto: 745Li
Thank you for this great writeup. It was very helpful when I replaced my compressor due to a failing bearing.

To give a cost overview, these are the specific tools and parts I had to get.
Manifold Gauges - 100$
Vaccum Pump - 160$ (Loaner-tool Autozone)
Can tap dispenser - 8$
HBNR O-Ring set - 8$

3x R134a - 340gr - 30$
1x PAG46 Oil - 10$
1x A/C Receiver Drier - RD10912KTC - 15$
1x Denso 471-1483 A/C Compressor - 375$ amazon

The nut and the bolt in the rear are a real disaster to get to, as described by apomerans. I was only able to loosen with an offset wrench and do the rest with my left hand. The harbor freight offset wrenches are not superb, as I found out. Get a decent 13mm one for the job.

My compressor came with plugs for the openings. These were quite convenient to reduce leakage while maneuvering the compressor in and out.

Have a funnel long enough ready to fill the oil in. Space is tight and its a long way.
Follow the TIS instructions on how to replace the receiver dryer 64 53 517.

When re-filling the a/c, note that it takes 810gr of r134a. I used scales to measure up the weight of the last bottle. 340gr + 340gr + 130gr from the last bottle. The can itself weighs about 100gr, plus tap dispenser and hose.


I found the following youtube video helpful.

Silver 2004 BMW E66 / 745Li (DIYs):
ASK, Logic 7, blower, battery, guibo joint, active stabilizer bar bushings, diff oil, tranny sw update, vacuum pump gasket, window lift, a/c compressor, washer fluid reservoir, belt tensioner and deflector, crankcase vacuum hoses, crankcase vents, solenoid gaskets, headlight overhaul, ISM, hood lifts, driver mirror, sway bar end links, rear fog lamps, headlight washer, headlight vertical aim, VCGs
next up: P0492

Last edited by flash_n; 11-03-2012 at 03:23 PM. Reason: added pictures
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Old 08-28-2014, 10:37 PM
springwater springwater is offline
Registered User
Location: USA
Join Date: Aug 2014
Posts: 35
Mein Auto: Gremlin
flash_n, I'm going ghetto. I bought some of the r134a and am just trying to fill it via the low side port.

Problem is, the end of the hose which is supposed to fit over the low side port is way too big for that space. The low side port is so close to the engine block, theres no room to fit it between the port and engine.

In your one picture, I noticed that you were able to fit the blue hose on to the port, can you tell me the name of the part you used (or provide a link to the part)?

(Looks like your port may actually be a little further away from the engine block)
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Old 08-08-2015, 09:11 AM
paulmurphyhomes's Avatar
paulmurphyhomes paulmurphyhomes is offline
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Location: Huntington Beach
Join Date: Feb 2007
Posts: 201
Mein Auto: M3, 745li, Speclzd FSR Pr

I was just replacing my water pump (and serpintine belt, idler, tentioner, vacuum lines and hoses) and found that I had to remove the harmonic balancer to get to the final bolt. I tried my best to do the stretch deal with a bottle jack, I tried a number of other attempts and 'almost' got it on.

Then I ordered one of these from NAPA:

It didn't work either (the lip on either side of the belt channels were too thick to fit in the slot of the tool).

Then I finally found a copy of the BMW service manual that references the BMW special tool.

BMW P/N 90 88 6 641 040

Which has been superceded by

BMW P/N 83 30 0 494 518

www.samstagsales.com sells this one for US$98


Looking a bit further, I found this one on ebay for US$54.89


I should get it next week and will post up my results.

Summary: As in most all cases, the right tool for the right job.

Last edited by paulmurphyhomes; 08-08-2015 at 09:15 AM. Reason: included search terms for search engine :)
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Old 08-12-2015, 02:56 PM
paulmurphyhomes's Avatar
paulmurphyhomes paulmurphyhomes is offline
Officially Welcomed to the 'Fest
Location: Huntington Beach
Join Date: Feb 2007
Posts: 201
Mein Auto: M3, 745li, Speclzd FSR Pr
Well, the tool worked flawlessly. I live in CA and the tool was delivered in a day.

Also, if you do like I did and actually installed the belt one groove too far in, just install the tool in the area that does not have the belt on it and rotate and you can persuade it to move one groove or another. I would even bet you could remove it that way as well.

Good luck!
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