Hi,

I have a Skoda Octavia Rider Classic 1.9 TDI 2005 model. The car was idle for a week and when I started found that the AC is not working. I had filled distilled water in excess in the battery and the acid had spilled below the battery compartment.

 

So far, I have checked the fuses. I have replaced both fans, battery, Fan control relay and the Temperature/Thermostat switch. When I insert the fuse, both fan starts to run for a few seconds and it stops. It happens whenever I pull out the fuse and reinsert it. When the power is supplied, the fan starts and stops. I checked the F18 3 pin connector which is hooked up to the Temperature switch. 1-2 doesn't work and the 2-3 works i.e. Low speed doesn't work and the high speed alone works. I have not checked whether the radiator fan switches when the coolant temperature raises when the AC is OFF.

 

Please post your views.

 

 

3 hours ago, Balaji27 said:

Temperature switch. 1-2 doesn't work and the 2-3 works i.e. Low speed doesn't work and the high speed alone works.

I'd suspect burnt out resistor(s) for the lower speed settings.

Thank you so much for the information. Could you please guide me in locating the resistor (s)?

5 hours ago, Balaji27 said:

When I insert the fuse, both fan starts to run for a few seconds and it stops. It happens whenever I pull out the fuse and reinsert it.

Which fuse do you mean?

 

There appear to be 3 fuses associated with the fan control module, a 10 amp one in the cabin fusebox, position 16, a 30 amp blade fuse in the battery-top holder (position 3a) for slow speed fans and a 40 amp strip fuse (middle position of the five) for radiator fan full speed.

 

Have you checked all three?

 

Were the replacement fans you fitted new or used items?

 

Have you checked that the connectors and their contacts which connect to the fan control module are unaffected by the spilt acid?

 

 

 

Yes, I have checked the fuses. I have also tried to replace with a spare one that I have. Fans are new ones. I have replaced the Fan Control Module. The contacts are unaffected by the spillage. I have also replaced the temperature switch.

3 hours ago, Balaji27 said:

Thank you so much for the information. Could you please guide me in locating the resistor (s)?

I'd guess behind the fan speed switch, but your exact model was never sold in Europe so I can't be certain.

Hi KenONeil and Breezy_Pete. Thanks a lot for your guidance.

 

It's my oversight. Please excuse me. I had checked the F18 connector without switching ON the ignition. Hence, I had mentioned that slow speed didn't work. Today, I started the engine and tested it and both fans are operating at low and high speed, when I connect 1-2 and 2-3 respectively in the 3 pin plug of temperature switch.

 

Fuse 16 (10 A) for Airconditioner and water pump is fine. I noticed a weird thing that both fans run, when the fuse 16 is removed. It runs even when the key is not inserted. When fuse 16  is inserted back, the fans stop. 

 

Please post your suggestions.

I took the car to an Electrician, he checked the Fan Control Module with his spare part. Fans didn't work. He changed the Ambient sensor with a spare one and it didn't solve. He checked the wiring completely and found that the ambient temperature sensor wire was cut off. He joined the wires and the fans started to work. AC refrigerant was less. He filled the refrigerant and everything works fine. There was no need to change the Fan Control Module, Fans and Thermostat switch.

The fans stopped working after a fews days. It worked earlier, after fixing the issue with wires connecting to the Ambient temperature sensor.  The outside temperature is not display on the instrument cluster. It shows____°C. I checked the connector of ambient temperature sensor. It shows 4 VDC. The sensor's resistance is 786 ohms. 

I have a, spare Fan control unit. Swapping the FCU doesn't help. Fuses are fine. What should I check next? 

Compressor is good and there is refrigerant I.e. no leakages. 

If repairing the wiring fixed the issue I'd be tempted to recheck it, especially if it does not now give a reading on the instruments.

 

I don't know what the sensor's supply voltage is but 4v seems suspiciously low.

The fans didn't work when I connected 1-2 or 2-3 of the radiator fan switch connector. There is 12 VDC at the radiator fan switch connector (thermostat switch). I checked both fans by applying voltage directly from the battery and they both work. There is no power supply at the connectors of both fans. Could it be ECM issue or wiring issues or something else?

If the 30A fuse in the battery fuse holder is bringing 12V on a red wire to pin 2 of the thermoswitch connector, and you are linking pins 1 and 2 of that connector with a thick wire, then both fans should start on their slow speed.  The wiring is the only other thing involved.

Direct power path highlighted by added red lines:

 

On 27/08/2022 at 07:57, Balaji2701 said:

Low speed doesn't work and the high speed alone works

 

If the resistor stack has burnt out/gone open circuit then only the highest speed will work.

It is found near the blower fan.

My sincere thanks to all who have shared your valuable inputs. The issue got fixed today. The connector which is on the 3 blade fuse box, on top battery, had melted. So there is no power supply to the fans. I have by passed the connector and added a fuse. Now everything is working as normal.