[s-cars] AC high pressure switch

[Erik Addy]

Yeah, it happens almost immediately.  I have pulled the codes myself, and I get the high pressure cut out code as well as an intermittent speed error.  The VAG-COM is required to recode the control head for the speed senor-less operation, right?  I think it is interesting that it didn't happen for a full week after the shop touched it, makes me wonder about the integrity of the sensor connections.


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> From: Joshua Van Tol <josh at spiny.com>
>To: Erik Addy <erikaddy at yahoo.com> 
>Cc: S-car-list <s-car-list at audifans.com> 
>Sent: Friday, July 25, 2014 9:13 AM
>Subject: Re: [s-cars] AC high pressure switch
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>It could also be the speed sensor failing on the compressor. How long did it take for the AC to cut off? If less than a few seconds, there's just no way that it could be high side pressure. The fact that it doesn't turn back on points to something other than the pressure switch. You might be able to re-code the control head for a denso compressor, which lacks the speed sensor to check this theory.
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>The head unit does have diagnostics, and will tell you if the speed sensor is bad or it's cutting off due to high head pressure.
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>My diagnosis is that it's time to get a VAG-COM and a gauge set and ditch the shop.
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>On Thu, Jul 24, 2014 at 3:01 PM, Erik Addy <erikaddy at yahoo.com> wrote:
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>Sorry I didn't reply to this earlier, I had to go out of the country for work and my personal emails sort of fell off my radar.  Anyway, I believe they put a gauge set on it.  Syptoms prior to brining it in were that frequently when I would start the car in the morning, the A/C compressor would engage (no noted abnormalities like dropping idle RPM or noise), and then immediately shut off and the snowflake symbol would disappear.  Occasionally, it would stay on and operate normally for the whole drive (typically 10-20 min).  After they worked on it, it worked every time for about a week or so, but now it is back to the symptom above.  Makes me wonder if they unplugged/plugged back in some connections and that make the contact better, which is why it worked for a while.
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>>Since it happens frequently right after a stone cold start, I can't imaging it is a blocked condenser or fan (but I've been wrong many times before).   I could see a partial block at the orifice tube or something... Where is the cut out switch?  Must be different than the switch that normally turns off the compressor, right?  Otherwise, why would the snowflake go away and the compressor not try to turn back on after the pressure drops?
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>>Erik
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>>>________________________________
>>> From: Joshua Van Tol <josh at spiny.com>
>>>To: Erik Addy <erikaddy at yahoo.com> 
>>>Cc: S-car-list <s-car-list at audifans.com> 
>>>Sent: Tuesday, July 15, 2014 7:27 AM
>>>Subject: Re: [s-cars] AC high pressure switch
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>>>What makes them think the problem isn't real? The switch is likely normally closed, so that it can be wired in series with other protection devices.
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>>>If the symptom is the AC works fine when the car is at speed, but sometimes quits right after start up or when in traffic, then I think you need to look at reasons why you might not be getting enough condenser airflow.
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>>>Is the aux cooling fan working? If it is, is the viscous clutch on the engine driven fan worn out? Last but not least, the condenser might be plugged up with bugs.
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>>>My S6 had a worn out barely working aux cooling fan, and the viscous clutch was worn. Replacing both fixed the AC. Cooling of the engine was not affected.
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>>>On Mon, Jul 14, 2014 at 3:39 PM, Erik Addy <erikaddy at yahoo.com> wrote:
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>>>So my AC is sometimes not working, throwing a code for the high pressure switch.  Shop says pressures are good, think it's an electrical issue.  Can any one tell me the location of the switch, and if open or closed circuit = high pressure cut off?
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>>>>Thanks!
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>>>>http://audifans.com/mailman/listinfo/s-car-list
>>>>http://www.audifans.com/kb/List_information
>>>>
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