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diagnosing aircon problem

Discussion in 'A4/S4 forum(B5 Chassis)' started by brendan, Aug 25, 2008.

  1. brendan
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    brendan 98 A4 1.8SE

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    [Aug 25, 2008]
    i know about three fifths of jack-all when it comes to air conditioning so could do with a little help diagnosing a problem with mine...

    firstly, since i owned the car it's never really blown that cold, although i've gathered that that's usually the case with audis. anyway recently it's packed up altogether. normal heating works fine, it's the air conditioning that doesn't seem to function (and when you're had ac/cc, you can never go back :)).

    these are the symptoms:
    1. press aircon button, light comes on as usual in the little display.
    2. temperature of air doesn't change at all.
    3. speed of air doesn't seem to change (though that could be me!).
    4. there's no drain on the engine.
    5. there's no added mechanical noise from the pump/engine - previously i could detect a slight noise when the aircon was actuated.

    only things i've checked are that there's still a belt and that the fuse is ok. is there some sort of process i could go through to determine what the problem is? could it be that the gas has totally leaked out? what's this relay that the haynes mentions about once? also i read on here something about a clutch - what's that about?

    any help / suggestions appreciated - cheers.
    #1
  2. dantdi
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    dantdi ...

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    [Aug 25, 2008]
    :hi:alright mate i had same thing. Have search under my name at aircon hope it helps.
    Dan
    #2
  3. Siena
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    Siena Active Member

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    [Aug 25, 2008]
    1) Aircon compressor clutch defective.
    2) R134-A refrigerant low.
    3) Pressure switch defective.


    I'd say it's number 2. Low refrigerant will trigger the low pressure switch, which will disable the compressor, to preserve the pistons.
    #3
  4. Blue_Thunder
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    Blue_Thunder Active Member

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    [Aug 25, 2008]
    You can get a defect code up on the Climate Control panel by doing the following:

    1) Hold recirc button and press the up arrow on the right hand side so that 1C is displayed.
    2) Press recirc button once (you can scroll through various other codes using the + or - buttons)
    3) This should show a fault code, ie: 20.1

    The codes are:

    [SIZE=-1]00.0[/SIZE] [SIZE=-1]No malfunction present[/SIZE] [SIZE=-1]
    02.1 (G86)[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Headliner, static open, *02.1 (see below)[/SIZE] [SIZE=-1]
    02.2[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Headliner, static short, see 02.1[/SIZE] [SIZE=-1]
    02.3[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Headliner, sporadic open[/SIZE] [SIZE=-1]
    02.4[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Headliner, sporadic short[/SIZE]
    [SIZE=-1]03.1 (G56)[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Instrument Panel, static open, see 02.1[/SIZE] [SIZE=-1]
    03.2[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Instrument Panel, static short, see 02.1[/SIZE] [SIZE=-1]
    03.3[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Instrument Panel, sporadic open[/SIZE] [SIZE=-1]
    03.4[/SIZE] [SIZE=-1]Interior Temperature Sensor, in Instrument Panel, sporadic short[/SIZE] [SIZE=-1]
    04.1 (G89)[/SIZE] [SIZE=-1]Fresh Air Intake Duct Temperature Sensor, static open, *04.1 (see below)[/SIZE] [SIZE=-1]
    04.2[/SIZE] [SIZE=-1]Fresh Air Intake Duct Temperature Sensor, static short, see 04.1[/SIZE] [SIZE=-1]
    04.3[/SIZE] [SIZE=-1]Fresh Air Intake Duct Temperature Sensor, sporadic open[/SIZE] [SIZE=-1]
    04.4[/SIZE] [SIZE=-1]Fresh Air Intake Duct Temperature Sensor, sporadic short[/SIZE] [SIZE=-1]
    05.1 (G17)[/SIZE] [SIZE=-1]Outside Air (Ambient) Temperature Sensor, front, static open, *05.1 (see below)[/SIZE] [SIZE=-1]
    05.2[/SIZE] [SIZE=-1]Outside Air (Ambient) Temperature Sensor, front, static short, see 05.1, *05.2 (see below)[/SIZE] [SIZE=-1]
    05.3[/SIZE] [SIZE=-1]Outside Air (Ambient) Temperature Sensor, front, sporadic open[/SIZE] [SIZE=-1]
    05.4[/SIZE] [SIZE=-1]Outside Air (Ambient) Temperature Sensor, front, sporadic short[/SIZE] [SIZE=-1]
    06.1 (G110)[/SIZE] [SIZE=-1]Engine Coolant Temperature (ECT), A/C static open, *06.1 (see below)[/SIZE] [SIZE=-1]
    06.2[/SIZE] [SIZE=-1]Engine Coolant Temperature (ECT), A/C static short, see 06.1[/SIZE] [SIZE=-1]
    06.3[/SIZE] [SIZE=-1]Engine Coolant Temperature (ECT), A/C sporadic open[/SIZE] [SIZE=-1]
    06.4[/SIZE] [SIZE=-1]Engine Coolant Temperature (ECT), A/C sporadic short[/SIZE] [SIZE=-1]
    07.1 (G109)[/SIZE] [SIZE=-1]Ambient Temperature Sensor at Fresh Air Blower, static open, *07.1 (see below)[/SIZE] [SIZE=-1]
    07.2[/SIZE] [SIZE=-1]Ambient Temperature Sensor at Fresh Air Blower, static short, see 07.1[/SIZE] [SIZE=-1]
    07.3[/SIZE] [SIZE=-1]Ambient Temperature Sensor at Fresh Air Blower, sporadic open[/SIZE] [SIZE=-1]
    07.4[/SIZE] [SIZE=-1]Ambient Temperature Sensor at Fresh Air Blower, sporadic short[/SIZE] [SIZE=-1]
    08.1 (G92)[/SIZE] [SIZE=-1]Temperature Regulator Flap Motor Potentiometer, static open, *08.1 (see below)[/SIZE] [SIZE=-1]
    08.2[/SIZE] [SIZE=-1]Temperature Regulator Flap Motor Potentiometer, static short, see 08.1[/SIZE] [SIZE=-1]
    08.3[/SIZE] [SIZE=-1]Temperature Regulator Flap Motor Potentiometer, sporadic open[/SIZE]
    [SIZE=-1]08.4[/SIZE] [SIZE=-1]Temperature Regulator Flap Motor Potentiometer, sporadic short[/SIZE]
    [SIZE=-1]08.5[/SIZE] [SIZE=-1]Temperature Regulator Flap, static block, *08.5 (see below)[/SIZE] [SIZE=-1]
    08.6[/SIZE] [SIZE=-1]Temperature Regulator Flap Motor Potentiometer, malfunction[/SIZE] [SIZE=-1]
    08.7[/SIZE] [SIZE=-1]Temperature Regulator Flap, sporadic block[/SIZE]
    [SIZE=-1]11.1 (G112)[/SIZE] [SIZE=-1]Central Flap Motor Potentiometer, static open, *11.1 (see below)[/SIZE] [SIZE=-1]
    11.2[/SIZE] [SIZE=-1]Central Flap Motor Potentiometer, static short, see 11.1[/SIZE] [SIZE=-1]
    11.3[/SIZE] [SIZE=-1]Central Flap Motor Potentiometer, sporadic open[/SIZE] [SIZE=-1]
    11.4[/SIZE] [SIZE=-1]Central Flap Motor Potentiometer, sporadic short[/SIZE] [SIZE=-1]
    11.5[/SIZE] [SIZE=-1]Central Flap, static block, *11.5 (see below)[/SIZE] [SIZE=-1]
    11.6[/SIZE] [SIZE=-1]Central Flap Motor Potentiometer, malfunction[/SIZE] [SIZE=-1]
    11.7[/SIZE] [SIZE=-1]Central Flap, sporadic block[/SIZE] [SIZE=-1]
    13.1 (G114)[/SIZE] [SIZE=-1]Footwell/Defroster Flap Motor Potentiometer, static open, *13.1 (see below)[/SIZE] [SIZE=-1]
    13.2[/SIZE] [SIZE=-1]Footwell/Defroster Flap Motor Potentiometer, static short, see 13.1[/SIZE] [SIZE=-1]
    13.3[/SIZE] [SIZE=-1]Footwell/Defroster Flap Motor Potentiometer, sporadic open[/SIZE] [SIZE=-1]
    13.4[/SIZE] [SIZE=-1]Footwell/Defroster Flap Motor Potentiometer, sporadic short[/SIZE] [SIZE=-1]
    13.5[/SIZE] [SIZE=-1]Footwell/Defroster Flap, static block, *13.5 (see below)[/SIZE] [SIZE=-1]
    13.6[/SIZE] [SIZE=-1]Footwell/Defroster Flap Motor Potentiometer, malfunction[/SIZE] [SIZE=-1]
    13.7[/SIZE] [SIZE=-1]Footwell/Defroster Flap, sporadic block[/SIZE] [SIZE=-1]
    15.1 (G113)[/SIZE] [SIZE=-1]Air Flow Flap Motor Potentiometer, static open, *15.1 (see below)[/SIZE] [SIZE=-1]
    15.2[/SIZE] [SIZE=-1]Air Flow Flap Motor Potentiometer, static short, see 15.1[/SIZE] [SIZE=-1]
    15.3[/SIZE] [SIZE=-1]Air Flow Flap Motor Potentiometer, sporadic open[/SIZE]
    [SIZE=-1]15.4[/SIZE] [SIZE=-1]Air Flow Flap Motor Potentiometer, sporadic short[/SIZE]
    [SIZE=-1]15.5[/SIZE] [SIZE=-1]Air Flow Flap, static block, see *15.5 (see below)[/SIZE]
    [SIZE=-1]15.6[/SIZE] [SIZE=-1]Air Flow Flap Motor Potentiometer, malfunction[/SIZE]
    [SIZE=-1]15.7[/SIZE] [SIZE=-1]Air Flow Flap, sporadic block[/SIZE] [SIZE=-1]
    17.0[/SIZE] [SIZE=-1]Vehicle Speed Signal faulty[/SIZE]
    [SIZE=-1]18.1[/SIZE] [SIZE=-1]Fresh air blower voltage, static[/SIZE] [SIZE=-1]
    18.3[/SIZE] [SIZE=-1]Fresh air blower voltage, sporadic[/SIZE]
    [SIZE=-1]20.1[/SIZE] [SIZE=-1]A/C compressor voltage not OK - static, *20.1 (see below)[/SIZE]
    [SIZE=-1]20.3[/SIZE] [SIZE=-1]A/C compressor voltage not OK - sporadic[/SIZE]
    [SIZE=-1]22.1 (F118)[/SIZE] [SIZE=-1]A/C Refrigerant High Pressure Switch, static open, *22.1 (see below)[/SIZE]
    [SIZE=-1]22.3[/SIZE] [SIZE=-1]A/C Refrigerant High Pressure Switch, sporadic open[/SIZE]
    [SIZE=-1]22.5[/SIZE] [SIZE=-1]A/C Refrigerant High Pressure Switch, 120X open, *22.5 (see below)[/SIZE] [SIZE=-1]
    29.1[/SIZE] [SIZE=-1]Belt slip detection "soft", static[/SIZE]
    [SIZE=-1]29.2[/SIZE] [SIZE=-1]Belt slip detection "hard", static[/SIZE]
    [SIZE=-1]29.3[/SIZE] [SIZE=-1]Belt slip detection "soft", sporadic[/SIZE]
    [SIZE=-1]29.4[/SIZE] [SIZE=-1]Belt slip detection "hard", sporadic[/SIZE]

    For more details, take a look at http://www.audiworld.com/tech/ and search for 'unlocking the secrets of the climate control panel'.

    HTH
    #4
  5. brendan
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    brendan 98 A4 1.8SE

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    [Aug 25, 2008]
    cheers, fellas! :)

    BT, will give that a go tomorrow and post back.
    dantdi, hope it's not that, lol - my car isn't worth much more than a grand!
    siena, i assume a refill from a reputable air-con specialist would sort that out? (subject to the fault code report thing)
    #5
  6. brendan
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    brendan 98 A4 1.8SE

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    [Aug 25, 2008]
    aah here we go:
    22.1 (F118) [SIZE=-1]A/C Refrigerant High Pressure Switch, static open, *22.1 (see below)[/SIZE]
    this is what i got :-/
    #6
  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Aug 26, 2008]
    high pressure is unusual...

    The refrigerant normally leaks out over time and causes the pressure to drop, and as siena says that triggers the low pressure switch to save the compressor from damage...

    High pressure i could only imagine means its been overfilled with gas, not really sure how you could have managed that though without having taken it somewhere to have gas added???
    #7
  8. Blue_Thunder
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    Blue_Thunder Active Member

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    [Aug 26, 2008]
    Could a blockage in the system cause the high pressure switch to trigger?
    #8
  9. jameshughes1974
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    jameshughes1974 Member

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    [Aug 26, 2008]
    High pressure could potentialy mean you have a blockage.
    Probably between the compresser outlet and the expansion valve.
    My guess is its the expansion valve which lives in one of the aircon pipes under the battery.
    They are cheap but the regas and service isnt.
    If it is this - you need to look at it as a sympton and not the cause.

    If its blocked - what is is blocked with?
    Aircon is meant to be a sealed system with nothing but refrigerant and compressor oil in it. has any body been putting leak sealer in it- this would be bad as it blocks the expansion valve with gunk.
    Or is is debris from a failing compressor.
    The compressers on the A4 are known for failing internaly.

    It could have been overfilled as this would cause the valve to ice up and block - when it defosts the process repeats - this would be the same if moisture was in the system (The main moisture culprit would be incorrect regas procedure or somebody using the instant aircon cans from ebay/halfords)

    Check the wiring on the pressure switch (located on the condenser(aircon rad)) though as i its easy and I think it can be replaced without degasing the system.

    I have been through the "aircon world" and I ended up replacing a compressor which did cure the problem.

    I would say that if a "specialist" does a leak pressure test and it passes i would judge this to be inconclusive. Nitrogen pressure testing is done at a lower pressure than your aircon is likely to meet on a hot day in normal operating conditions.

    Remember If it leaks its because something has failed.

    Good luck
    #9
  10. dsmclark40v
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    dsmclark40v Member

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    [Aug 26, 2008]
    I had that code. does it kick in cold when you start moving? as mine had a problem with the electric fan that cools the a/c's radiator in the engine bay. the matey who fixed it for me said the pressure went up dangrously high. he said i was lucky it didn't blow! i got a new fan for about £45 if i recall. to check it your best bet would be to see if it comes on when the a/c is switched on.
    Sam
    #10
  11. brendan
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    brendan 98 A4 1.8SE

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    [Aug 26, 2008]
    hmm the plot thickens (see below).
    thanks again everyone for their input, btw - definitely food for thought.

    did another check on the way home today and using that method above, i got a result of ".0". the a/c wasn't enabled at the time so i'll have to nip out again and see if that makes a difference.

    i've had the car for 6 years and nothing has been done to the system in that time. the a/c has been working fine (albeit not arctic-like) up until a month or so ago - while not on constantly, i always ran it at least every couple of days to keep the fluids moving etc.

    dsmclark30v, stationary or moving makes no difference. i did notice today that the fan speed does change when the a/c is switched on (as normal) so everything seems normal apart from no cooling / no pumping being done.

    edit:
    forgot to mention, the car is lowered to the max and the compressor and pipes are quite close to the gound (no engine shield panel in place at the moment). having said that, i have looked underneath and can't see any damage to the pipes or compressor.

    anyway cheers for the advice that keeps coming. anything to help me fix it in the least-expensive way possible!! (certainly couldn't justify £450 when i'm struggling to find £150 to have my new cam chain tensioner fitted! :))
    #11
  12. brendan
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    brendan 98 A4 1.8SE

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    [Aug 26, 2008]
    tried it again while i was driving along - 22.1 error as before. sounds like it could be a sticky valve then? will check the connections etc. as advised.

    thx,
    #12
  13. OldAudiA4B5
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    OldAudiA4B5 New Member

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    [Jan 29, 2014]
    Did anyone ever work out what this was?

    As I have the exact same error code at the moment with the A/C Compressor not working as the compressor is not cutting in.
    #13
  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Jan 29, 2014]
    Could be a bad pressure switch or a wiring fault?
    #14

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