Hi

 

I have been trying to identify the cause of a problem (checked various forums) and am finding mixed info but no definitive test to locate what is wrong with my 06 Octavia.

 

The problem is that the both radiator cooling fans start running full blast when the car is parked and they are flattening the battery, this is intermittent and even happens if the car has not been run for days so is stone cold.

 

So far I have:

1. extracted and visually checked the ECU - its dry and all contacts are clean and ist now had a spray of ACF50 (better than WD40) to expel moisture. Note - the fault even occurs if the ECU is removed!

2. Stripped out the fuse board in the engine bay, cleaned and dried it and given a coating of ACF50 to expel moisture

3. Checked external temp sensor it seems to be working correctly as it is responding to hot /cold accurately

 

Questions:

A. Is there a reliable way of testing the fans on their own to see if the integral unit is the cause?

B. what should the voltage values be on the 2 control signal wires be at the harness plug where the fans are connected to the body wiring?

C. whats left/ what have I missed out?

 

Thanks 

A scan for fault codes may help.

Sent from my Nexus 4 using Tapatalk

About what car we talking about?

Anyway sounds like defective Fan Control Module.

A fairly common problem on the Octavia, see here for the fix...

 

http://www.briskoda.net/forums/topic/132047-vrs-engine-cooling-fan/?hl=%2Bfan+%2Bstuck#entry1759291

Thanks for the suggestions but have exhausted the previous threads.

The car is 06 MK2 Octy 2 litre Laurin and Klement fsi petrol.

There is no external fan control. It's not the same as the mk1 which did have external unit ( been there done one of them I the past)

Edited 13 January, 201511 yr by ownerjag

There is no external fan control. It's not the same as the mk1 which did have external unit ( been there done one of them I the past)

Yes, you're right MKII has a relay, like  silver1011 mentioned that could be your problem.

Mine did this when the coolant temp sensor went. No fault codes stored either. Replaced sensor all been fine since.

Mine did this when the coolant temp sensor went. No fault codes stored either. Replaced sensor all been fine since.

Mine did this when the coolant temp sensor went. No fault codes stored either. Replaced sensor all been fine since.

Mine did this when the coolant temp sensor went. No fault codes stored either. Replaced sensor all been fine since.

Faulty sensor doesn't mean 'fault code'...wrong readings will never count as error and ECU react all readings taken in account.

Hi

Fans kick in with no ecu fitted.

Getting a 7 to 8 volt reading on the red and blue coloured wire at the plug on the fan cowling.

Suggestions?

Hi the large fan is the control module. You have 4 wires big red = live ..big brown= earth 2 smaller wires can't remember colours . One of the small wires is an activation on wire from climatronic and the other is activation from ecu for fan activation via temperature. So you have 3 suspects engine ecu or climatronic or larger fan (which is the control module for the smaller fan) if I was you i would get a 2nd hand .. larger fan with the same part number and try that 1st. Had a similar experience on mk5 golf fsi many years ago and the larger fan cured it. Good luck with it.

Edited 19 January, 201511 yr by FLAPPERJACK7

I hate to tell you this but mine also did this under warranty. It was recovered twice. The found no errors and tried the relay. In the end it required replacment of the ECU. It cost £2,500 but luckily Skoda paid out.

 

Im sure that there will be a cheaper way of resolving this.

 

Good luck.

 

Garnett

mine has done this twice in the last year, put alarm on and five minutes later fan starts going full pelt, starting the car stopping starting again fixed it but still a worry. Especially the last time as i was 200 miles away from home. Both occasions have been 6 month apart.