Col
17-07-2008, 02:18 PM
I think I know the answer already but if anyone knows anymore or has had any experience of this, please let me know?
The car is a 2002 Passat Estate PD TDI (130hp) Engine code AWX, this may also effect Audi A4's or A6's as well.
Symptoms;
Whilst stuck in a lengthy traffic jam the other night the aircon hissed and cut out. (good shows the pressure switch / safety system is working).
Water temp remained at 90 (these are hopelessly inaccurate anyway so I don't trust it).
My aux oil temp gauge, fitted with sump mounted sender, rose up to 100 degrees, normally it is always bang on 90.
Anyway I put the climate into econ mode and sat it out. Note I never ever normally get stuck in traffic like this so this problem proabably pre-exists me owning the car. Also the aircon normally blows ice cold.
Anyway, got through jam onto open road, oil temp soon returned down to 90 and I pressed the auto button on the climate to re-engauge the aircon, nice cold air again.
My tests and diagnosis;
Having not had any previous problems until I researched this issue, the fan should run at low speed all the time the aircon is on. My fan does not.
Test 1. - Fan
Disconnected fan wiring and connect straight to battery, this would make the fan work at full speed. Nothing at first, I then tapped the fan motor body and it slowly sprung to life. It now starts a high speed ok.
Test 2. - Power supply to fan.
Removed under panel by pedals and checked all the hidden fuses mounted on the relay plates first of all.
Pulled of 4 pin coolant temp switch plug on bottom of rad (this one only controls the fan). It is a 2 speed switch. Anyway I bridged the following (with ignition on);
terminals 1 and 4 (brown and red/green) = Fan worked on high speed.
terminals 2 and 3 (brown and brown/black) = No worky fan
I could hear both the high and low speed relays clicking inside the car so that rules them out.
Test 3. - Supply voltage at fan plug (the plug on the holder by the power steering res).
With terminals 1 and 4 bridged = Battery voltage
With terminals 2 and 3 bridged = 8.2 volts
This test in my mind eleminates the fan resistor.
My questions and conclusion...
My conclusion is, having tested, checked and verified everything is working, is that the fan itself is simply worn out! It struggled to get going under full battery voltage and in my opinion the reduced 8v to run the low speed simply doesn't provide enough oomph to make it spin.
Questions;
1, Should the low speed voltage be 8v ?
2, Is it possible to remove the fan without removing the rad ? I accept it will be necessary to put the lock carrier in the service position.
Any help, comments or suggestions more than welcome.
The car is a 2002 Passat Estate PD TDI (130hp) Engine code AWX, this may also effect Audi A4's or A6's as well.
Symptoms;
Whilst stuck in a lengthy traffic jam the other night the aircon hissed and cut out. (good shows the pressure switch / safety system is working).
Water temp remained at 90 (these are hopelessly inaccurate anyway so I don't trust it).
My aux oil temp gauge, fitted with sump mounted sender, rose up to 100 degrees, normally it is always bang on 90.
Anyway I put the climate into econ mode and sat it out. Note I never ever normally get stuck in traffic like this so this problem proabably pre-exists me owning the car. Also the aircon normally blows ice cold.
Anyway, got through jam onto open road, oil temp soon returned down to 90 and I pressed the auto button on the climate to re-engauge the aircon, nice cold air again.
My tests and diagnosis;
Having not had any previous problems until I researched this issue, the fan should run at low speed all the time the aircon is on. My fan does not.
Test 1. - Fan
Disconnected fan wiring and connect straight to battery, this would make the fan work at full speed. Nothing at first, I then tapped the fan motor body and it slowly sprung to life. It now starts a high speed ok.
Test 2. - Power supply to fan.
Removed under panel by pedals and checked all the hidden fuses mounted on the relay plates first of all.
Pulled of 4 pin coolant temp switch plug on bottom of rad (this one only controls the fan). It is a 2 speed switch. Anyway I bridged the following (with ignition on);
terminals 1 and 4 (brown and red/green) = Fan worked on high speed.
terminals 2 and 3 (brown and brown/black) = No worky fan
I could hear both the high and low speed relays clicking inside the car so that rules them out.
Test 3. - Supply voltage at fan plug (the plug on the holder by the power steering res).
With terminals 1 and 4 bridged = Battery voltage
With terminals 2 and 3 bridged = 8.2 volts
This test in my mind eleminates the fan resistor.
My questions and conclusion...
My conclusion is, having tested, checked and verified everything is working, is that the fan itself is simply worn out! It struggled to get going under full battery voltage and in my opinion the reduced 8v to run the low speed simply doesn't provide enough oomph to make it spin.
Questions;
1, Should the low speed voltage be 8v ?
2, Is it possible to remove the fan without removing the rad ? I accept it will be necessary to put the lock carrier in the service position.
Any help, comments or suggestions more than welcome.