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a/c mystery

Discussion in 'Air Conditioning' started by photoguy7174, Jul 19, 2009.

  1. photoguy7174
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    photoguy7174 New Member

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    hi, first time poster. i have a 2000 tt quattro, recently my a/c quit blowing cold air. i thought it needed rechg. i took it to my mechanic who said it was still good. he checked for any leaks an did not find any. the compressor was also working along with the fans turning on. he is stumped as to why no cold air . one of the hoses gets cold when the a/c is on but only up to the refill cylinder then beyond that its warm ,he feels there might be somthing blocking the line . however we removed the high pressure line and blew it out with air . any suggestions would be great. a complete rebuild was suggested for 2000 dollars yikes
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  2. Staz
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    Staz is a retronaut Staff Member Moderator

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    Welcome!

    When you say removed the high pressure line and blew it out with air what do you mean exactly?

    It could be that there isn't enough refrigerant in the system. Although there is some there, and I'm guessing enough to not cause the low pressure cut out to trigger, it could cause a reduction in the efficiency.

    Just try one thing for me please. Start the engine and put the air con in ECON straight away. Turn the climate control to Lo and select the recirculation mode. Give it a few minutes like that to get the cabin temperature to the lowest it'll get to without cold air.

    When you're happy it's stabilised deselect ECON mode. I know you've said the condensor fans kick in ok but just double check that you hear them start.

    Once the fans kick in just check if there is any reduction in temperature whatsoever.

    This'll tell you if it's either just not working efficiently or not working at all.
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  3. photoguy7174
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    photoguy7174 New Member

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    thank you for your timely response. to clairfy about the hose, i completely detached the hose at both ends (compressor and firewall),then per my mechanics reccomendation blew it out then reattached the hose took it back to my mechanic who then refilled the system with freon. needless to say it did not resolve my problem. now to get to your suggestion. i followed your directions as you requested but when i disengaged the econ button the fans did not turn on. i wonder if they only turned on for me when the car was hot.
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  4. Staz
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    Staz is a retronaut Staff Member Moderator

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    Ok well your mechanic is an idiot. You can't just vent refrigerant to atmosphere, as it's illegal. And blowing air through the system will put moisture into it. Before refilling it he would have needed to do a deep vacuum. This can take an hour or 2. Did he do that?

    Depending on the model the fans will also be using for cooling the engine, that's probably where the confusion lies.

    Did ECON actually disengage? If you had left it running I would expect the high pressure cut out to trip and then ECON would be engaged all the time.
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  5. photoguy7174
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    photoguy7174 New Member

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    im starting to feel like the idiot here. i know my mechanic did a deep vacum before he told me to remove the high pressure hose and blow air thru it. but after i replaced the hose i took it back to him and all he did was put freon back in th system. did this ruin my entire a/c? as far as the econ goes i did not see it re-engage after i turned it off, and what i mean by this is that the econ light never came back on , nor has it ever done this ever since the a/c quit working. also im a little confused about the fan sitaution. could you please explain again when exactly each fan should turn on. again thanks for your help and patience
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  6. Staz
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    Staz is a retronaut Staff Member Moderator

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    It won't be ruined no, not so soon. Basically when you refill a system it should be empty to start with. As in pretty much a vacuum. By filling it with air and then refrigerant you now have air and refrigerant going around the system. The air also contains moisture. There's a thing called a filter drier that absorbs moisture but it won't last forever. So any extra moisture will cause damage (rust) inside the system. Plus as the system now has air+refrigerant the efficiency is compromised.

    What you now need is a recovery, a deep vacuum to remove all the moisture and then a fill of FRESH refrigerant as the other lot contains the air.

    The fans thing I don't know about for your car but it can be worked out. On an A3 for example there are 2 fans attached to the front of the car. 1 alone is used for the air con and both together are used for cooling the engine.

    Because of this you should check the air con system when the engine is cold so initially no fans are running with the engine on. Then when you press ECON to turn it off the only fan to run will be the condensor fan. If no fans are running at all then the system SHOULD realise it and disable the air con (putting the ECON light on permanently). It seems that this is not always the case though and you'll think everything is fine but the fan isn't running (although the fans WILL be running if the engine is hot don't forget!!). If you run an air con system without any air flow over the condensor you'll get a build up of high pressure and then the HPCO (High Pressure Cut-Out) will trip and then the system WILL be disabled and then the ECON should come on and stay on.

    The problem with faults on air con is there are so many factors and it's important to suss out each of the main symptoms before going deeper. The fans not coming on is a pretty big one.

    Can you get access to VCDS (vag.com)?
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  7. photoguy7174
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    photoguy7174 New Member

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    thanks again for your response. regarding the vag, i actually had that run on my car at the same time my a/c was being worked on. the reason being was that i also had an abs light on. which turned out to be a longitudinal sensor. but there were no other error codes that came up. so im not sure if that helps eliminate anything. i also spoke to my mechanic and he said that once he got the a/c working he was going to do a deep vacum and refill of the system. at this point i was thinking that my main focus should be on the condenser fan,checking for a bad fuse or sensor and then work backward from there. any additional suggestions or advise would be greatly appreciated.
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  8. photoguy7174
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    photoguy7174 New Member

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    corection on my earlier post. i thought vcds was the scanner for diagnostic codes. my bad. so iguess the correct respone is no i dont have access .
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  9. Staz
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    Staz is a retronaut Staff Member Moderator

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    VCDS IS the scanner for diagnostics. Although not a basic one and does a lot more.

    If you have a fault code scanner I would have thought it should be able to read the same code I was expecting.

    danny104 in this thread had problems and it turns out his fan was broken although there was never a fault code logged for it.

    If you can be sure that with a cold engine turning ECON off doesn't kick one of the fans in then there's your problem mate. I would assume it's a 2 pin connector to it, if so then do a voltage check across the pins with an without ECON.
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  10. photoguy7174
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    photoguy7174 New Member

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    ok sounds good ill get right on trying to find the sensor/switch for that fan and check to see if its the problem. ill keep you posted on my progress . thans again
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  11. photoguy7174
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    photoguy7174 New Member

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    well im back. a quick update, i purchased a new fan control module put it in and did not fix my a/c problem. things actually got worse. now my fans do not turn on at all, even when the car gets hot. i checked both fans with a 12v direct connect both are functional. i also checked the fuse located at the top of the battery its good. so now im stuck with no fans and no a/c. is there a relay under the dash that could have gone bad? or is there somthing else im missing? the car has not ever overheated on me. stuck need some help
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  12. Staz
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    Staz is a retronaut Staff Member Moderator

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    I don't know the circuit mate so I can't help too much. Where did you get the fan control module?? If it's new it's unlikely that it's made the problem worse. Have you tried running the car hot so the fans would normally kick in?
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  13. photoguy7174
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    photoguy7174 New Member

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    okay i finally gave up and took my car to the dealers. at first they told me it was a blown high pressure switch and it would cost 359.00 to replace, i was actually quite suprised that i was going to be so cheap to fix such a big headache. then i got a call from the dealer that the switch didnt fix the problem and that now they need to replace the high pressure line because it has a clogged valve bringing my bill to 539.00 . well i figured its still not that bad . not done yet, i get acall again from guess who, you got it the dealers . now they tell me my compressor is not working. what? are you kidding me , i told them i never had a problem with the compressor it was working just fine to which they replied
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  14. photoguy7174
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    photoguy7174 New Member

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    sorry continued from earlier post. the dealer agreed that the compressor was working but that while they had it it just quit. the cost to replace, a whopping 1700.00. not to worry because they say there going to give me a smokin good deal considering what i have invested in repairs so far.i cant help but feel like im getting shafted here. i thought the dealerships were suppose to know what their doing. oh well thats my story i'll keep you posted and let you know how it ends. for some reason i get the feeling they're not done with me yet or my check book
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  15. Staz
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    Staz is a retronaut Staff Member Moderator

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    Unfortunately the dealers are great at replacing things but not so good at the diagnostics. There have been cases on here where they have scanned the car for faults and said it's ok instead of simply looking, listening and hearing.

    When it comes to air con it seems not many people are good at putting the symptoms together and working out the cause. I'd alway recommend going to an independant specialist rather than a dealership. I don't mean a garage that does air con too, I mean a place/guy who ONLY deals with air con.

    It's normal to charge you for their misdiagnosis mate. It's very poor practise and when it comes to paying the bill argue as much as possible. Audi service guys don't like a scene!
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  16. photoguy7174
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    photoguy7174 New Member

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    i went to the dealers today to check on my car, i was assured that the foreman and two of their most senior techs took a look at my car and guaranteed me that the new compressor and drier were going to fix the problem 100%. and the deal they gave comes out to 1200 bucks,they didnt charge me for the high pressure switch or high pressure line minus also any labor involved in tha that work. i guess if i get out only paying 1200 i will concider myself lucky. keep ya posted
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  17. Staz
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    Staz is a retronaut Staff Member Moderator

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    I'd still be a bit annoyed as the compressor worked when you took it in!
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