Erratic climate control? Typical or fixable?
03-06-2002, 05:32 AM
#1
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Erratic climate control? Typical or fixable?
I have a problem getting heat settings to generate a consistently comfortable temperature. With both sides set a 71 degrees, I will often find cold air puffing on my feet, and at other times in my face; and of course this morning the car was a sauna. I can usually achieve comfort by manually setting the fan speed and output vents, but then I'm defeating the system. Could it be a bad sensor?
03-06-2002, 05:52 AM
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Definitely doesn't sound typical. In all 3 A6's that I've owned, the climate control system has
maintained a fairly even temperature. My only complaint is that the fan motor/blower is definitely too loud.
03-06-2002, 06:37 AM
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Mine's eratic, too, doesn't do a good job of dealing with solar radiation
Another problem is that the system simply doesn't move enough air, although it makes an impressive amount of noise for the volume of air it does move.
Regards
Regards
03-06-2002, 08:58 AM
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I've had infrequent (1/week) problems in which it is about 5 degrees too cold...(long)
For example, on one cloudy day when sun should have been a minimal factor, it was perfect at 70 for awhile. Upon restarting, it needed to be turned up to 75 to give the same result.
It is most noticable in summer and cold winter, as that is when the fan speeds need to be highest.
first, we checked for obvious sensor errors... the AC computer is only capable of detecting outright short or open, not intermittencies of any other type (not as smart as the engine ECU). So far, we haven't found anything. Another possibility is that the interior air sampling fan (tiny grate in middle of console between seat warmers, I think) may be malfunctioning or dead. It could be an AC unit electrical or even software problem.
My dealer has a request for info into Audi. I'll let you know if I learn anything. You can do the same at your dealer... may prompt them to look into it. At first, typically, they come up with rationale such as the sun sensor to explain that it is working normally. But I allow for that, and only "blame" the system in clear-cut cases of the problem.
Keep in mind that the car's roof and other sensors go into the determination of what the blower air temp should be. It is not the desired temp, but an extreme temp to help bring the cabin towards what it thinks is the right temp. Using all the interior and exterior sensors, it makes a guess as to what you're experiencing at present. So, to determine if there is a real problem, it is best if you haven't just restarted the car after sitting in the sun, and better if the problem comes on without having to restart and under stable environmental conditions; then you can be more sure it is a real problem and not just "normal" behavior.
One way to check what temperature the AC thinks it is in the cabin is to turn up both settings until the fan reaches minimum speed. That is the temp where least change is needed. I find it to be either right on, or about 5-8 degrees off, never in between. This tells me there is a real problem.
I have yet to find information on the diagnostics available by pressing key combinations... I can access them, but I just don't know what each channel means, and there are dozens, perhaps a hundred, including speed, sensor temperatures, and more.
It is most noticable in summer and cold winter, as that is when the fan speeds need to be highest.
first, we checked for obvious sensor errors... the AC computer is only capable of detecting outright short or open, not intermittencies of any other type (not as smart as the engine ECU). So far, we haven't found anything. Another possibility is that the interior air sampling fan (tiny grate in middle of console between seat warmers, I think) may be malfunctioning or dead. It could be an AC unit electrical or even software problem.
My dealer has a request for info into Audi. I'll let you know if I learn anything. You can do the same at your dealer... may prompt them to look into it. At first, typically, they come up with rationale such as the sun sensor to explain that it is working normally. But I allow for that, and only "blame" the system in clear-cut cases of the problem.
Keep in mind that the car's roof and other sensors go into the determination of what the blower air temp should be. It is not the desired temp, but an extreme temp to help bring the cabin towards what it thinks is the right temp. Using all the interior and exterior sensors, it makes a guess as to what you're experiencing at present. So, to determine if there is a real problem, it is best if you haven't just restarted the car after sitting in the sun, and better if the problem comes on without having to restart and under stable environmental conditions; then you can be more sure it is a real problem and not just "normal" behavior.
One way to check what temperature the AC thinks it is in the cabin is to turn up both settings until the fan reaches minimum speed. That is the temp where least change is needed. I find it to be either right on, or about 5-8 degrees off, never in between. This tells me there is a real problem.
I have yet to find information on the diagnostics available by pressing key combinations... I can access them, but I just don't know what each channel means, and there are dozens, perhaps a hundred, including speed, sensor temperatures, and more.
03-06-2002, 09:12 AM
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Same complaint; dealer has tried unsuccessfully to fix it.
I think Audi's sensor(s) and/or control algorithm are poor. It seems impossible to get a true set & forget setting. My M/B autotemp setting never froze or baked me. Not a big deal, but it is a peeve.
03-06-2002, 10:37 AM
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panel diags and scan codes (more)
key is to be able to check the reported temps from each sensor right when it happens. do you have a scan tool or software?
re: panel codes, have you tried the tables for A4 codes (link)? might be similar... or not...
for scan tools, measuring block 008 gives you the 4 temp sensors it uses to adjust (left/right vents, floor vent, instrument panel). that with block 007 (outside and engine temp) will tell you what the climate head thinks is happening.
BTW, good call on the mini-fan in the dash - it classically fails in the older cars (like my 200). the claim for the AC head is also that it will 'suppress measured values from a malfunctioning sensor' but i doubt how well that works, especially if your malfunction is intermittent and minor - if a sensor is only off by 5F the computer probably doesn't know it...<ul><li><a href="https://www.audiworld.com/tech/int5.shtml">panel codes</a></li></ul>
re: panel codes, have you tried the tables for A4 codes (link)? might be similar... or not...
for scan tools, measuring block 008 gives you the 4 temp sensors it uses to adjust (left/right vents, floor vent, instrument panel). that with block 007 (outside and engine temp) will tell you what the climate head thinks is happening.
BTW, good call on the mini-fan in the dash - it classically fails in the older cars (like my 200). the claim for the AC head is also that it will 'suppress measured values from a malfunctioning sensor' but i doubt how well that works, especially if your malfunction is intermittent and minor - if a sensor is only off by 5F the computer probably doesn't know it...<ul><li><a href="https://www.audiworld.com/tech/int5.shtml">panel codes</a></li></ul>
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03-06-2002, 12:14 PM
#8
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Thanks... thinking about buying VAG tool, questions...
You listed some blocks to find the temps... is that kind of information (which blocks are what) something that comes with the VAG tool? Or, is found when connected to the Audi? Otherwise, where do I find this kind of info?
Got a small laptop I can dedicate to the task.
Yeah, I have a printout of codes for another Audi, probably A4, but it isn't the same (dual channel, and the channel numbers don't match).
Got a small laptop I can dedicate to the task.
Yeah, I have a printout of codes for another Audi, probably A4, but it isn't the same (dual channel, and the channel numbers don't match).
03-06-2002, 08:58 PM
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no, code stuff is all in the manual... (long post on VAG-COM)
I have VAG-COM software from Uwe Ross (below). Software is still in beta, but is a great effort for a homegrown. You can download it and see it in 'demo' mode, but need a special cable to connect it to your car, and then need to activate it to really get to do anything good.
With it some things are self-explanatory because Uwe includes cool 'Label' files that give names for measuring block numbers as well as decoding of DTC's error codes (much more than the proprietary VW tool does for you). Also you can log data blocks to disk, then graph and analyze them later. In your case, you could log temp sensor data for 2 driving sessions and compare what was happening the time it malfunctioned vs. the time it worked fine...
However, to get the most out of it requires having the factory manual CD also, which has just become available from Bentley (or through Uwe if you're a software customer). Then you have all the info to diagnose, re-code and adapt modules, change convenience features and do all kinds of scary things to screw up your car ;^)
Other sources of info for codes and usage include a support newsgroup and people like me who are happy to look up whatever you need in the A6 manual as long as I have time.
I highly recommend having this if you're at all self-maintaining or mechanically/technologically inclined or interested, however a warning: a number of people either seem to have outrageous expectations for the software ("can someone post the instructions to recode my CD player to run X-box games?") or are woefully over their head - if you have to ask what a MAF or FPR is, then getting codes about them malfunctioning isn't going to do you much good, right?<ul><li><a href="http://www.ross-tech.com">Ross Tech</a></li></ul>
With it some things are self-explanatory because Uwe includes cool 'Label' files that give names for measuring block numbers as well as decoding of DTC's error codes (much more than the proprietary VW tool does for you). Also you can log data blocks to disk, then graph and analyze them later. In your case, you could log temp sensor data for 2 driving sessions and compare what was happening the time it malfunctioned vs. the time it worked fine...
However, to get the most out of it requires having the factory manual CD also, which has just become available from Bentley (or through Uwe if you're a software customer). Then you have all the info to diagnose, re-code and adapt modules, change convenience features and do all kinds of scary things to screw up your car ;^)
Other sources of info for codes and usage include a support newsgroup and people like me who are happy to look up whatever you need in the A6 manual as long as I have time.
I highly recommend having this if you're at all self-maintaining or mechanically/technologically inclined or interested, however a warning: a number of people either seem to have outrageous expectations for the software ("can someone post the instructions to recode my CD player to run X-box games?") or are woefully over their head - if you have to ask what a MAF or FPR is, then getting codes about them malfunctioning isn't going to do you much good, right?<ul><li><a href="http://www.ross-tech.com">Ross Tech</a></li></ul>