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#11
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Radiator Fan Controls
Stephen Clark wrote: > Thanks, Tony, I was vaguely aware of how the fan controls work. The only > thing I have noticed that is abnormal, other than the fan coming on very > briefly when the car is off after a hot run, is that fan speed two has not > worked with the a/c off for quite some time. For example, if I am in stop > and go traffic in the winter, and the engine gets hot enough, fan speed > three will come on ( sounds like an aircraft taking off! ) until the > coolant temp drops below it's preset threshold. The engine never overheats, > so this has not been a problem from a practical point of view, so I have not > done anything about it. > > However I usually have the a/c on about eight months out of the year, > because it's hot and muggy in Houston even in the spring and fall. Fan speed > one is sufficient to keep the coolant temp normal with the a/c on, and I'm > not sure that fan speed two ever comes on when the a/c is kept on all the > time. > > I'm thinking maybe I should check/replace the relay for fan speed two? If > the temp sensor were the culprit, why would fan speed three operate at all? > Am I on the right track? > > I'll send Steve Sears your greeting! > > Have a great Memorial Day weekend... > > Sounds lie you are on the right track in diagnosing the fan. I would suggest changing the thermo switch on the bottom of the radiator as it is most likely the problem with speed two. It could also be the fan speed two relay. You can easily unplug the thermo switch and jumper the connections to operate speeds two and three. If Two doesn't run then its the thermo switch. However, given that your fan seems to be operating fairly well I would guess that your battery drain is due to something else. You could try pulling relays / fuses and checking for current draw with the ingition off. |
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#12
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New information after 3 days...
I have let the car sit for three days without using it, in order to monitor
the battery's state of charge. Started out three days ago with a full charge of 12.63 volts. It is now down to 12.38 volts after three days of sitting. That's about a 0.25V drop over three days. Measured the residual current draw at the battery cable connection to be 81.5 ma. This is with everything off, including interior lights. The only draws should be clock, radio memory, and alarm. Is this a reasonable draw? Might I still have a battery that is not holding charge sufficiently? The auto parts store won't warranty it, because their equipment shows the battery to be good, and it is only six months old. Also, the radiator fan has not come on in three days, so I am ruling that out as a possible cause of a sudden discharge. I am puzzled as to what could have brought the battery to it's knees in the brief 10 minutes I was in the grocery store three days ago. Nothing was left on that would have drained the battery that fast. I can only assume that there is a fault in the battery, but I can't prove it to the auto parts store folks. -- Stephen Clark 89 Audi 100 Houston, Texas USA |
#13
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New information after 3 days...
On Sat, 26 May 2007 18:23:01 -0500, "Stephen Clark"
> wrote: >I have let the car sit for three days without using it, in order to monitor >the battery's state of charge. > >Started out three days ago with a full charge of 12.63 volts. It is now down >to 12.38 volts after three days of sitting. That's about a 0.25V drop over >three days. > >Measured the residual current draw at the battery cable connection to be >81.5 ma. This is with everything off, including interior lights. The only >draws should be clock, radio memory, and alarm. Is this a reasonable draw? >Might I still have a battery that is not holding charge sufficiently? The >auto parts store won't warranty it, because their equipment shows the >battery to be good, and it is only six months old. > >Also, the radiator fan has not come on in three days, so I am ruling that >out as a possible cause of a sudden discharge. I am puzzled as to what >could have brought the battery to it's knees in the brief 10 minutes I was >in the grocery store three days ago. Nothing was left on that would have >drained the battery that fast. I can only assume that there is a fault in >the battery, but I can't prove it to the auto parts store folks. 82 MA (I rounded up) is a *bit* high, but totally out of line. Generally you want it below 50 MA if possible. Consider also that some loads may come and go, so a current logging setup may be needed. |
#14
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New information after 3 days...
PeterD wrote: > On Sat, 26 May 2007 18:23:01 -0500, "Stephen Clark" > > wrote: > >> I have let the car sit for three days without using it, in order to monitor >> the battery's state of charge. >> >> Started out three days ago with a full charge of 12.63 volts. It is now down >> to 12.38 volts after three days of sitting. That's about a 0.25V drop over >> three days. >> >> Measured the residual current draw at the battery cable connection to be >> 81.5 ma. This is with everything off, including interior lights. The only >> draws should be clock, radio memory, and alarm. Is this a reasonable draw? >> Might I still have a battery that is not holding charge sufficiently? The >> auto parts store won't warranty it, because their equipment shows the >> battery to be good, and it is only six months old. >> >> Also, the radiator fan has not come on in three days, so I am ruling that >> out as a possible cause of a sudden discharge. I am puzzled as to what >> could have brought the battery to it's knees in the brief 10 minutes I was >> in the grocery store three days ago. Nothing was left on that would have >> drained the battery that fast. I can only assume that there is a fault in >> the battery, but I can't prove it to the auto parts store folks. > > 82 MA (I rounded up) is a *bit* high, but totally out of line. > Generally you want it below 50 MA if possible. Consider also that some > loads may come and go, so a current logging setup may be needed. I remember hearing that batteries can develop internal shorts due to residue below the cells but that is only likely in the case of old or re-cycled batteries so probably not what you experienced. A problem that the T44 series had that caused battery drain and the occasion fire was due to the battery being under the rear seat and close to the steel seat springs. The battery included a nylon cover that snapped over the positive battery terminal to insulate from the springs when people sat in the seat. If the part was not replaced when changing batteries there was the potential for problems. I am not sure if this is possible on your car but might be something to consider. Let us know what you find. |
#15
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New information after 3 days...
On Sat, 26 May 2007 20:35:50 -0400, PeterD > wrote:
> >82 MA (I rounded up) is a *bit* high, but totally out of line. >Generally you want it below 50 MA if possible. Consider also that some >loads may come and go, so a current logging setup may be needed. I should slow down when I type, I meant to say: "*bit* high, but NOT totally out of line." IOW, it would be nice to be below 50 (or even better below 30), 80 isn't the end of the world. |
#16
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New information after 3 days...
Yes, I understood your meaning, thanks.
I am looking at the charging voltage of 13.88 volts, and thinking that's a bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that is about 14 mos. old. But, then I haven't started the car since Thursday, and today the battery voltage at the jumper post is 12.35. The original charge was 12.63 after a quick charge at the auto parts store on Thursday. Is that too much of a drop? I'm trying to determine if maybe there is a fault in the battery, like an intermittent shorted cell. Other sources say that 75 ma is the max parasitic draw, so 82 isn't extreme. It wouldn't have pulled the battery completely down during the 10 minutes I was in the grocery store. Is a puzzlement.... "PeterD" > wrote in message ... > On Sat, 26 May 2007 20:35:50 -0400, PeterD > wrote: > > >> >>82 MA (I rounded up) is a *bit* high, but totally out of line. >>Generally you want it below 50 MA if possible. Consider also that some >>loads may come and go, so a current logging setup may be needed. > > > I should slow down when I type, I meant to say: > > "*bit* high, but NOT totally out of line." > > IOW, it would be nice to be below 50 (or even better below 30), 80 > isn't the end of the world. > |
#17
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New information after 3 days...
Stephen Clark knastet inn: :
> Yes, I understood your meaning, thanks. > > I am looking at the charging voltage of 13.88 volts, and thinking that's a > bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch that > is about 14 mos. old. But, then I haven't started the car since Thursday, > and today the battery voltage at the jumper post is 12.35. The original > charge was 12.63 after a quick charge at the auto parts store on Thursday. > Is that too much of a drop? I'm trying to determine if maybe there is a > fault in the battery, like an intermittent shorted cell. To eliminate battery fault; Recharge, disconnect it, and do the same test as described above. If you find no significant voltage drop, it's a leak elsewehere. |
#18
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New information after 3 days...
"Stephen Clark" > wrote in message ... > Yes, I understood your meaning, thanks. > > I am looking at the charging voltage of 13.88 volts, and thinking that's a > bit low. Should be closer to 14.4 V. The alternator is a re-built Bosch > that is about 14 mos. old. But, then I haven't started the car since > Thursday, and today the battery voltage at the jumper post is 12.35. The > original charge was 12.63 after a quick charge at the auto parts store on > Thursday. Is that too much of a drop? I'm trying to determine if maybe > there is a fault in the battery, like an intermittent shorted cell. > > Other sources say that 75 ma is the max parasitic draw, so 82 isn't > extreme. It wouldn't have pulled the battery completely down during the > 10 minutes I was in the grocery store. > > Is a puzzlement.... > Hi Stephen, dropping 300mV in "at least" three days seems quite believable to me. Once charging has ceased (engine off) the terminal voltage will fall quite quickly to an open circuit value say 12.65V and assuming a capacity of nominally 40A/Hr a 100mA load would take approximately 14 days to fully discharge the battery down to say 10.5V My guess would be a week and the car might be hard to start? - so no obvious anomalies from your information so far. 14.2V is more suited to short runs than 13.88, depends on your normal trip duration whether your present voltage is a bit low. 13.65V is a "float" or continuous charge voltage. Regards Dave |
#19
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I think I had an intermittent short...
Thanks to you all for your kind contributions. The battery is holding now at
12.34 volts. I am beginning to think that what caused the discharge incident was an intermittent short of some kind in the electrical system somewhere, possibly the classic problem of the harness in the driver's door jamb. I have had trouble with the driver's window working intermittently lately, but it is working ok now. If I happened to cause a short when I closed the door to go into the store that day, then that could have caused the battery to go flat very quickly. I don't know why a fuse did not blow, but perhaps the current draw wasn't sufficient to blow the fuse, but just enough to drain the battery. I suppose the battery was just too low to jump, or we had bad connections between the cars. Anyway, that is my best theory to date. I'll either take a look at the harness wires myself, or have my mechanic do it this week. I'll let you all know what, if anything, we find. Happy Memorial Day to all! -- Stephen Clark 89 Audi 100 Houston, Texas USA |
#20
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Mechanic says there is nothing wrong
I spoke with my trusted Audi mechanic today on the phone, describing the
incident, and what I had done to try to diagnose it. He says there is nothing wrong as the car stands today. He said if it were a short in the driver's door jamb, it would have blown a fuse, and I would have found smoke and burned wires. He further said that those circuits are not large enough to cause a failure like I described. So I am left with an one-time mysterious event, that is undiagnosed, and will have to wait until a hard failure occurs to correct it. So wish me luck that it doesn't happen again. Thank again to all for your suggestions. Happy Motoring! |
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