2004 AUDI A8- radiator fans on all the time!!
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1st Gear
Joined: Dec 2010
Posts: 18
From: IL.
auditech:so its coolant temperature sensor? what about (thermal switch)?
silver...i did change the sensor once on passat and didn't have to drain the coolant.Anyways coolant temperature sensor was the problem for engine temperature indicator sudenly go off and on in passat and after i replaced everything was fine.So on my a8(d3) the temperature is showing properly.
silver...i did change the sensor once on passat and didn't have to drain the coolant.Anyways coolant temperature sensor was the problem for engine temperature indicator sudenly go off and on in passat and after i replaced everything was fine.So on my a8(d3) the temperature is showing properly.
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From: Nor Cal
I've never had to replace the fan switch on a D3 A8, and i can't find any information regarding a fan switch on a D3, so i'm assuming the ECM is doing the brain work. Its just my best guess that the temperature sensor is sending faulty signals to the ECM and in turn it keeps the fans on. Again since i don't have access to the manual, this is just a guess, hopefully someone can run thru the diagram real quick to confirm.
As for the comment above, the sensor on the passat you're referring to is the one on the back of the engine, thats the wrong sensor.
As for the comment above, the sensor on the passat you're referring to is the one on the back of the engine, thats the wrong sensor.
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Joined: Jun 2010
Posts: 624
The part you changed on the Passat (I have 2) was the temp sensor for the gauge and ECM on top rear of motor (V6)...but has nothing to do with the fan.
The thermo switch that controls the fan on the Passat is on the lower radiator hose fitting and drains the radiator when it's removed..in fact that's how I drained the radiator when I changed the pump and thermostat, because it's easier to remove than the hose.
On a D2 the thermo switch that controls the fan is on the lower radiator and will drain it as soon as it comes out. The temp sensor for gauge and ECM on the D2 is at top rear of motor and has nothing to do with the fan operation.
I think the D3 is similar and to my knowledge, the temp sensor for ECM/gauge also has nothing to do with fan operation. In Passat and D2 the thermo switch was on the radiator or fitting, since the fan operation depends on the temp of the coolant in the radiator in particular.
EDIT: I think we were posting at the same time, but we agree...I think
The thermo switch that controls the fan on the Passat is on the lower radiator hose fitting and drains the radiator when it's removed..in fact that's how I drained the radiator when I changed the pump and thermostat, because it's easier to remove than the hose.
On a D2 the thermo switch that controls the fan is on the lower radiator and will drain it as soon as it comes out. The temp sensor for gauge and ECM on the D2 is at top rear of motor and has nothing to do with the fan operation.
I think the D3 is similar and to my knowledge, the temp sensor for ECM/gauge also has nothing to do with fan operation. In Passat and D2 the thermo switch was on the radiator or fitting, since the fan operation depends on the temp of the coolant in the radiator in particular.
EDIT: I think we were posting at the same time, but we agree...I think
Last edited by silverd2; Dec 23, 2010 at 08:57 PM.
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1st Gear
Joined: Dec 2010
Posts: 18
From: IL.
ok...i think we get mixing in too many cars..(passat, D2).
From what my mechanic say the d2 have replacable ecm.The d3 have ecm as part of fan and cannot be purchased separately.Thats why i need new fans or fan to resolve the problem.
The website i get refer from silver have universal fans and they no help because they dont have the ecm.
Bassicaly what they say i need ecm and because that cannot be purchased separately i'm stuck with only option to get new fan.
So you think auditech as well it is ecm sending the problem?
From what my mechanic say the d2 have replacable ecm.The d3 have ecm as part of fan and cannot be purchased separately.Thats why i need new fans or fan to resolve the problem.
The website i get refer from silver have universal fans and they no help because they dont have the ecm.
Bassicaly what they say i need ecm and because that cannot be purchased separately i'm stuck with only option to get new fan.
So you think auditech as well it is ecm sending the problem?
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Joined: Jun 2010
Posts: 624
NOT too many cars...they all operate on the same principles...we're trying to help you NOT get taken by a mechanic who knows more than you and is using that to his advantage.
ECM is the engine control module (NOT the fan control module!)....I don't think you're getting this. That has nothing to do with what we're getting at.
Temp sensors generally send signals to the ECM for engine management purposes (fuel mixture, ignition timing) and temp gauge in the car.
The thermal switch in question (not the temp sensor), is one that sends signal to turn on the fan to cool down the radiator....TWO DIFFERENT PARTS in both D2's and Passat.
In the case of your car (D3), it may use a temp "SENDER" to do the same thing.
At this point, it might be abetter idea to just hand your wallet to the mechanic and tell him to do what ever he thinks best....OR GET A SECOND OPINION.
I'm done....good luck to you.
ECM is the engine control module (NOT the fan control module!)....I don't think you're getting this. That has nothing to do with what we're getting at.
Temp sensors generally send signals to the ECM for engine management purposes (fuel mixture, ignition timing) and temp gauge in the car.
The thermal switch in question (not the temp sensor), is one that sends signal to turn on the fan to cool down the radiator....TWO DIFFERENT PARTS in both D2's and Passat.
In the case of your car (D3), it may use a temp "SENDER" to do the same thing.
At this point, it might be abetter idea to just hand your wallet to the mechanic and tell him to do what ever he thinks best....OR GET A SECOND OPINION.
I'm done....good luck to you.
Last edited by silverd2; Dec 23, 2010 at 11:44 PM.
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Joined: Jun 2010
Posts: 624
I'm a glutton for punishment and haven't quenched my thirst for knowledge. SO...First, I recommend (unless you want to burn $1800) that you:
1. Do not allow THAT mechanic to proceed to you understand your car's cooling set up.
2. Get a manual for your car. EVERYONE (whether they do their own work or not) should have one, to avoid confusion and be forearmed before blindly accepting a mechanic's diagnosis. Worth every penny...will save you a fortune. I've bought a manual for every car I've ever owned. Here is the best one for yours: http://www.bentleypublishers.com/aud...009-ebahn.html
3. Carefully read all posts pertaining to your car by aspen79, auditech79 and the latest info I am providing. We are trying to help and learn ourselves.
That said, first I did not give you a site with universal fans...the $420 fan I told you of and the site that sells it is a fan for your car WITH the built in fan control unit.
I've learned (as far as I can tell) your car actually has 2 electric radiator fans, 2 different part numbers, BOTH of which have a built in control unit:
LEFT:
4E0959455G
electric fan with control unit
600W 390MM 13 BLATT BOSCH left / PR-8Z6 BFM,BFL,BBJ, ASN,BNG,ASB
RIGHT:
4E0959455H
electric fan with control unit
600W 390MM 11 BLATT BOSCH right / PR-8Z6 BFM,BFL,BBJ, ASN,BNG,ASB
As I said before, they are BOTH available from:
http://www.genuinevwaudiparts.com/pa...?siteid=214407
At $420 each. Punch the part # into the box on the first page and you'll see each listed.
BUT, there is is NO WAY that both fans are bad at the same time...impossible (or at least EXTREMELY improbable..this should tell you VOLUMES about THAT mechanic!). Both fans are apparently controlled by a temperature SENDER. There is a 99% chance that the sensor is the reason for the malfunction, as we have suggested. The sensor is also available from the same source (above), AS I SAID BEFORE....you can find this sensor by:
1. Punch in your car
2. Look under "cooling system"
3. Then look in "cooling fan" subsection
4. Then hit "temp sending unit"
5. $17.76
NOTE: I have learned also, that there is more than 1 temp sensor on the D3 engine, each with a specific purpose. The one they have listed (above) is apparently the one that send signals to the fan control unitS. It will take a manual OR an HONEST, QUALIFIED mechanic to locate that one, which REALLY should be ON or NEAR the radiator. One parts supply drawing I saw shows it on the radiator, next to the lower hose (as on a D2)...BUT can't be sure of that WITHOUT A MANUAL or looking for myself, which I can't.
That's the best I can do with research.
Cheers
1. Do not allow THAT mechanic to proceed to you understand your car's cooling set up.
2. Get a manual for your car. EVERYONE (whether they do their own work or not) should have one, to avoid confusion and be forearmed before blindly accepting a mechanic's diagnosis. Worth every penny...will save you a fortune. I've bought a manual for every car I've ever owned. Here is the best one for yours: http://www.bentleypublishers.com/aud...009-ebahn.html
3. Carefully read all posts pertaining to your car by aspen79, auditech79 and the latest info I am providing. We are trying to help and learn ourselves.
That said, first I did not give you a site with universal fans...the $420 fan I told you of and the site that sells it is a fan for your car WITH the built in fan control unit.
I've learned (as far as I can tell) your car actually has 2 electric radiator fans, 2 different part numbers, BOTH of which have a built in control unit:
LEFT:
4E0959455G
electric fan with control unit
600W 390MM 13 BLATT BOSCH left / PR-8Z6 BFM,BFL,BBJ, ASN,BNG,ASB
RIGHT:
4E0959455H
electric fan with control unit
600W 390MM 11 BLATT BOSCH right / PR-8Z6 BFM,BFL,BBJ, ASN,BNG,ASB
As I said before, they are BOTH available from:
http://www.genuinevwaudiparts.com/pa...?siteid=214407
At $420 each. Punch the part # into the box on the first page and you'll see each listed.
BUT, there is is NO WAY that both fans are bad at the same time...impossible (or at least EXTREMELY improbable..this should tell you VOLUMES about THAT mechanic!). Both fans are apparently controlled by a temperature SENDER. There is a 99% chance that the sensor is the reason for the malfunction, as we have suggested. The sensor is also available from the same source (above), AS I SAID BEFORE....you can find this sensor by:
1. Punch in your car
2. Look under "cooling system"
3. Then look in "cooling fan" subsection
4. Then hit "temp sending unit"
5. $17.76
NOTE: I have learned also, that there is more than 1 temp sensor on the D3 engine, each with a specific purpose. The one they have listed (above) is apparently the one that send signals to the fan control unitS. It will take a manual OR an HONEST, QUALIFIED mechanic to locate that one, which REALLY should be ON or NEAR the radiator. One parts supply drawing I saw shows it on the radiator, next to the lower hose (as on a D2)...BUT can't be sure of that WITHOUT A MANUAL or looking for myself, which I can't.
That's the best I can do with research.
Cheers
Last edited by silverd2; Dec 24, 2010 at 09:36 AM.
Thread Starter
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1st Gear
Joined: Dec 2010
Posts: 18
From: IL.
silver: thank you thats what i need to clearified all inputs here.
Same think i told my indy that 2 fans respectively fan control units cannot go wrong at least 99.9%.
i think is well worthet to replace the TSU and see what happend.If i understand bumper have to be removed.
Same think i told my indy that 2 fans respectively fan control units cannot go wrong at least 99.9%.
i think is well worthet to replace the TSU and see what happend.If i understand bumper have to be removed.