Tell me about aircon pumps.

  1. ukracer Forum Supporter

    OK chaps I am in need of a lesson. How does an aircon pump as filled to a B6 2008 2.0 TDI 16 Valve Passat actually work.

    I think the end in the middle is supposed to stay still until the aircon is on. What I dont know is a few things lol
    How is the 3 vane clutch is pulled in...I can only assume its Hydraulic as I cant see how an electro magnet would work in this type.

    If the Pump is stuck on would/should the aircon be on all the time. (It was not working even when filled with Gas) Chap filled it with Gas .we tested it and it did not get cold so he took it all back out again so I could take the pump off.

    Upon taking the pump of we can see the inner and outer were seized together. Even now they are not seized together it is hard to push in and out (leading me to think its hydraulic)

    Finally the Bolt had come out of the end of the pump and reading on line it seems to be a common thing.....not nice when you have to remove the damn front of the car to change the pump....

    I stand by to be educated... Thanks in advance.
     
  2. gordon stephenson

    gordon stephenson Forum Supporter

    Messages:
    6,340
    Location:
    Skelton in Cleveland U.K.
    As far as I know the air-con pulley is pulled in electrically,
     
  3. welshpug

    welshpug Member

    Messages:
    84
    South Wales
    typically yes its an electromagnetic clutch, sanden or valeo are the two most common brands found.
    with no gas/oil in the system the pump will likely be worn out if the clutch did seize on, which I think is not likely as the default no power applied is off.

    the bolt coming out of the end I have heard of, the splines of the shaft to the hub can be damaged if this happens.

    service position on many vw's involves moving the front panel one screw forwards after removing the bumper skin so not unusual there!
     
  4. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    I think that pump uses an internal cluchso nothing to see unless you strip it.

    Did you san the air con system for fault codes? If you lose pressure it will store a fault code for it. Just regassing without clearing the fault won't allow the air con to work.
     
    rtcosic likes this.
  5. ukracer Forum Supporter

    Mmmm no they just regassed and did not clear fault codes.
     
  6. ukracer Forum Supporter

    If its electro magnetic where is the power to it? There is only power to the valve...
     
  7. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    If it has an external clutch there will be two wires running to a little fitting right next to the pulley, but i think B6s use an internal clutch pump. Do have a picture of it? The pulley on that should only have a damper in it.

    You need to scan the HVAC module for faults. I've had a number of VWs with no AC due to failed pressure switches (easily bypassed for diag) or even ones that've lost gas, had the leak repaired and been regassed but no codes cleared so no AC.

    Next step is to scan for codes and go from there.

    Was it actually low on gas to start with? If so, you need to go a nitrogen/dye test and a vacuum test to check for a leak.
     
    rtcosic likes this.
  8. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    If it looks like this and the 2-pin connector is on the back then your clutch is internal.

    Genuine-Sanden-AC-Compressor-A-C-06-07-VW-GTI-_1.jpg

    This is a pump with conventional electromagnetic clutch pulley:

    61Zu63fR3LL._SX425_.jpg

    (See the wires running to connection behind pulley.)
     
    eddie49, Parm and rtcosic like this.
  9. ukracer Forum Supporter

    Its internal clutch like this . But how does it work. The inner and outer were constantly spinning...

    How do i bypass the pressure switch as its saying closed circuit on delphi diagnostic. Its also 3 wire connector.
     
  10. ukracer Forum Supporter

    Screenshot_20190717-011813_eBay.jpg

    But i cant fathom out how they work and how the clutch is operated...
     
  11. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    There is no inner and outer with an internally-clutched pump. The pulley has a damper inside which is just 6 little rubber blocks, it works like a dual-mass flywheel. The clutch is inside the pump, so you will not be able to see it.

    If you have a 3-pin it's harder, the older 2-pins you just bridged. I'll ask a mate if he knows a bypass for 3-pin.

    Does your Delphi show any fault codes in HVAC? You should at least have one for low pressure. (Since there's no gas)
     
    rtcosic likes this.
  12. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    That's not for your car. Like i said, it's internal to the pump. So not a serviceable item.

    On an externally-clutched pump the outer pulley spins all the time with the engine running. Turn on AC, electromagnetic clutch switches on and the clutch engages. It work opposite to a transmission clutch; normally disengaged by spring pressure, the electromagnetic clutch will engage the plates together to lock the inner and outer pulley parts and spin the pump.

    Yours works in the same principle, but the clutch is inside the pump assembly.
     
    eddie49 and rtcosic like this.
  13. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    External clutch:

    compressor-clutch.jpg
    The clutch coil is mounted to the front of the pump housing.

    The pulley's bearing inner race is mounted to the "nose" on the front of the pump housing, allowing the pulley to spin free, yet held in place by the bearing.

    The clutch is attached to the pump shaft, which passes through the nose of the housing. (riding in it's own bearing inside the nose) there are two friction surfaces, one on the clutch and one on the pulley. (the brown ring) the clutch springs (the 3 fingers in the pic you posted) are the clutch springs which hold the friction rings apart with the clutch disengaged, when the electromagnetic clutch coil is energized it pulls the clutch closed, engages the friction rings and locks the clutch (and so the pump shaft) to the pulley to spin the pump.
     
    eddie49 and rtcosic like this.
  14. rtcosic

    rtcosic Member

    Fortunately I didn't need all this information, but I appreciate posting all that detail, so a thank you to Moose McAlpine :thumbup:
     
    Anguz, ukracer and stuvy like this.
  15. ukracer Forum Supporter

    20190717_124958.jpg 20190717_125009.jpg 20190717_125014.jpg
    Thats whats confusing me. See pics above your quote thats my actual compressor.

    But the only electrical connection to the pump is purely the valve......and as i say unless its hydraulic i can see how it works.

    Its a solenoid but only operates a valve not electromagnet as far as i can see.

    Before it was removed the whole pulley was spinning....we freed it up and just the outer was spinning....

    Which is why i cant see why aircon was not working (as i have tested valve and it works) unless the Air pressure switch had failed.

    I.e it should have been constantly running aircon pump as it was seized in the operating position.
     
  16. ukracer Forum Supporter

    My pump definately has that type of pully. But the original brand new one seems not to. BUT the repair kit looks like the pulley on my pump........my concern is that the pump fitted its the wrong one as all ebay vehicle checkers are saying 5K0820803A does not fit my car.....aarrrgggg.
     
  17. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    Has the air con ever worked? That front drive pulley definitely broken, the spring ends have come away from the centre hub.

    Did you remove the solenoid from the back of the pump? There will only be one electrical connection on the pump.

    It looks like yours is a variable displacement pump, and as such there is no clutch. It runs all the time and that control valve regulates its operation.



    Anyway that pulley should not spin independant of the centre hub. Have you tried VW for a repair kit? They usually sell them so you can repair the hub and get the right part.

    Did it have any fsult codes?
     
  18. ukracer Forum Supporter

    20190718_174648.jpg

    Only code left on now.....new pump and air pressure switch fitted..
     
  19. Moose McAlpine

    Moose McAlpine Member

    Messages:
    327
    Location:
    Watford Hertfordshire
    Is it now gassed too?
     
  20. ukracer Forum Supporter

    Not till tomorrow mate. (later today now) lol
    We are guessing that error would be there if it has no gas or the Air con pressure switch is duff.
     
Advertisements