AC Compressor / System 4.8i

[gregg3gs]

Hello All,


My 08 e70 is starting to develop AC Compressor issues (140K miles)
It still works but the barring or clutch is starting to squeak like a failing pump does.

From the manuals I see it is easy to replace (or so it seems).
BMW Workshop Manuals > X Series E70 X5 4.8i (N62TU) OFFRD > 2 Repair Instructions > 64 Heating And Air Conditioning > 52 Compressor > 3 RA Removing And Installing_replacing A_C System Compressor (N62TU)

My plan:
- I plan on having local shop evaluate the system
- next I want to replace the compressor (and maybe a dryer as well)
- from what I read you should not drive the car until you refill the ac system, I wanted to drive to the mechanic to get the system refilled

Here are few questions:
- is there something I can do to fill the AC system temporarily?
- is there a chance I can drive the car with AC belt off?
- is there a diy that maybe I missed?
- if the system is working: do I have to replace the dryer?

All your input is greatly appreciated.

[lanbrown]

You could always put some freon in the system and then let the shop properly fill the system. The LCI models take 1.54 pounds of refrigerant. My system would cool just not extremely well and the dealer only evacuated .51 pounds of refrigerant. So it was 1/3 full and the system would work and could cool the cabin on a 80 degree day; 85 degrees it struggled with. So if your system takes 1.54 pounds, put a 16oz bottle in and then let the mechanic put the rest in.

[gregg3gs]

Originally Posted by lanbrown

You could always put some freon in the system and then let the shop properly fill the system. The LCI models take 1.54 pounds of refrigerant. My system would cool just not extremely well and the dealer only evacuated .51 pounds of refrigerant. So it was 1/3 full and the system would work and could cool the cabin on a 80 degree day; 85 degrees it struggled with. So if your system takes 1.54 pounds, put a 16oz bottle in and then let the mechanic put the rest in.

Sounds like the approach I may be taking.
Good idea.

What about the compressor oil?

[lanbrown]

I do not know about the compressor oil. You would need to get a service manual or access to one to see what the official word is.

[Doug Huffman]

The essential operation usually unavailable to the DIYer is evacuating and drying the system. It will never work right with air in the freon vapor and evacuation boils off any moisture in the system.

[mkurniawansyah]

Can't you just disabled the AC compressor using the snowflake button?
I'm under the impression that this will disengage the compressor clutch (compressor shaft not rotating) but the pulley remain rotating along with the engine.

[gregg3gs]

Originally Posted by trader4

Since no one has responded, I'll give you my 2 cents. The issue here
would seem to be whether the compressor can turn, thereby damaging
itself before being properly charged. You can disable the clutch by
leaving the wire disconnected or pulling the appropriate fuse. The only
remaining issue I see would be whether a compressor with no charge
is so easy to spin that somehow, even though the clutch isn't engaged,
it would turn some anyhow. I doubt that's possible, but I'm no expert
on the AC compressor.

But for sure without the AC belt on, the compressor can't turn at all.

My thoughts exactly.
I was hoping to leave the AC compressor belt off but the 4.8 engine uses single belt.
I am not sure about leaving the electrical connector off.
It certainly will keep the compressor from coming on but the pulley is still spinning.

[Davidf]

Originally Posted by gregg3gs

My thoughts exactly.
I was hoping to leave the AC compressor belt off but the 4.8 engine uses single belt.
I am not sure about leaving the electrical connector off.
It certainly will keep the compressor from coming on but the pulley is still spinning.

No, the A/C compressor has its own ribbed belt. So, yes you can leave the belt off. But, you can certainly install the belt and leave the electrical connector disconnected. I think if you simple turn off the compressor (with the snow flake button) there might be instances where the climate control system will activate compressor anyway (i.e humidity control). But, the system has a low pressure cut-out switch so it probably would not engage anyway.

Be warned that the A/C compressor tensioner pulley adjusting bolt is a real PITA. Many of us cut a notch in the end of the bolt so a screw driver can be used to snug it up (or loosen) before final tightening. once you look at it, you will see what I mean. This might only be an issue if you have Dynamic Steering, Sport, etc.

If the compressor clutch does not engage, then there is no harm in having the belt installed. The clutch bearing is sealed/self lubricating. if you have the compressor rebuilt, ask the shop to fill with the proper viscosity oil. If you purchase new, you need to do your research and fill with proper amount and the proper viscosity PAG oil. The proper oil viscosity (i.e. 43, 56, 100, 150, etc) is CRITICAL. If you find data for total system oil quantities, then assume 1 oz of oil remains in each major component (other than the compressor).

Good luck.