Air con problem diagnosis

Beefbeefbeef Apr 19, 2015

  1. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Tried the air con the other day, admittedly for the first time in months, and it's not working (I know, you're meant to turn it on occasionally just to keep the seals from drying out but I haven't).

    On listening carfeully, I can't hear the compressor kicking in which may mean a compressor problem. I did have a problem a few years ago with one of the air con pipes corroding but because a few of the pipes had corroded together, i had to replace a long stretch of pipework which cost a bomb to replace.

    Anyway, does anyone have any alternative theories as to why I'm not hearing the compressor? I'm getting it looked at tomorrow.
     
  2. farmerboy

    farmerboy New Member I am in uk

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    Interior fan switched on I suppose?
     
  3. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Yes, full blast.
     
  4. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    Magnetic clutch failure - had 3 of those happen to me. Last one seemed ok. I think they fit them two g sometimes ;)
     
  5. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Thanks Gary. interesting. Any idea what the magnetic clutch does so that I can talk semi competently in front of the air con man? I didn't follow your last sentence - "two g".
     
  6. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    Damn autocorrect. Should say 'badly'.

    The magnetic clutch is what drives the compressor when it's switched on by the A/C switch on the dash - can get very noisy and then fail. I think it's possibly bearing related. It's linked in via the serpentine drive belt on the front.

    Easy-ish test is to open bonnet, have engine running and get someone to switch on A/C - you should hear a clack as it engages.

    It won't do that if there is no gas though - I also had bad seals in the piping cause issues.
     
  7. StarCruiser

    StarCruiser Well-Known Member Supporter Guru I am in uk

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    As Gary says, there will be a low pressure switch in the piping which stops the compressor during normal operation and if there is insufficient gas. The modern refrigerant is such a small molecule it leaks out through the compressor shaft seal, especially if not used once a week or more. Chances are, the system may be short of gas. An easy fix to have it checked by a refrigeration engineer and topped up if necessary. Or, Halfords do a self recharge canister which has a gauge but if I were you I would go the pro route.

    The electrical side of the clutch can easily be checked with a multimeter. There should be a plug in the wiring for a single wire near to and feeding into the clutch which sits inside the pulley on the compressor. Carefully separate the connector and test, with the meter on 'Ohms', across from this wire on the compressor side to a good earth, compressor body is fine for this. You should get a reading, not sure what but no reading means a fault in the coil. Test from the other side of the connector that comes from the rest of the wiring on the car. With AC, engine and fan on there should be battery voltage on this wire. Again test with the meter on 'V' to the compressor body or any earth point on the car. No voltage reading indicates probably shortness of gas, blown fuse, or other electrical problem.

    First place to start is get the system checked for gas level. You can look for leaks around any pipe work joints which leak a tiny amount of oil and attract dirt. If there's a lot of these it may be worth emptying the system and replacing all these seals before recharging with gas.
     
    Last edited: Apr 19, 2015
  8. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    And the seals can be found online - Halfords do a set but no idea what they're like quality wise
     
  9. farmerboy

    farmerboy New Member I am in uk

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    Try Quik Fit for a re-gas - if it does not work they do not charge.
     
  10. StarCruiser

    StarCruiser Well-Known Member Supporter Guru I am in uk

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    If you do decide to change seals then ensure system is depressurised first and clean scrupulously around any joint you open and maintain this level of cleanliness until the system is reclosed. It must then be put on vacuum (which any proper refrigeration engineer will do) before adding the correct amount of gas.
     
  11. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    My compressor isn't kicking in - I can normally hear the clack from the inside of the car (plus the revs change a little as it loads the engine) and can't at the moment. Saying that, if there is not enough gas in the system then I understand the compressor won't start so it could be a leak or a compressor problem. My usual air con guy has retired (I found out today) so need to find someone else.
     
  12. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Thanks. My only concern with that is that when I had a leak last time, the re-gas worked initially until all the new gas leaked out a day or two later! So I would have handed over my cash to Kwik-crook by then and I wonder how easily I could get it back off them!
     
  13. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    That 'clack' is the magnetic clutch engaging. If all the unicorn fart leaked out after 2 days then QED there is a leak. And not aways from a joint - check the pipe in front of the radiator for corrosion too.

    Good luck!!
     
  14. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    No, it leaked out in two days four years ago when I had a corroded pipe.

    If there is no leak but a problem with the magnetic clutch then I guess the symptoms would be the same as I have now i.e. no "clack" noise. So at the moment it could be either a leak or a clutch / compressor problem.
     
  15. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    Have you looked in the sight-glass to see if you have a bubble?? If there isn't one chances are the gas is gone
     
  16. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Where is the sight-glass located?
     
  17. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    In the engine room just to the right and fwd of the air filter housing is the A/C pipework - you should see a bubble glass viewer in the pipe there. I 'think' there may be another - I'd need to go look at some pictures or the FSM
     
  18. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    Thanks. Will have a butcher's later on.

    BTW, is there a separate compressor running the rear air con?
     
  19. Gary Stockton

    Gary Stockton Super Moderator Supporter I am in zimbabwe

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    No compressor I think But there is a fan behind the right rear panel in the boot, next to the subwoofer. All runs on the same system - but you can turn the rear a/c off on the console controls obviously.
     
  20. Beefbeefbeef

    Beefbeefbeef Member I am in uk

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    I can't recall ever getting chilled air in the rear and wondered why (the blower works though). I have ignored it as the front fans are pretty strong and soon cool the rear with the air con on full blast.
     
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