Hey all, need some help with diagnosing cooling fans.

 

2010 Octavia FL vRS wagon. 2.0 TSI

 

• Cooling fans don't run when the car gets hot, especially idling/traffic.  The Dash gauge doesn't go above 90 in this instance, but the VCDS temp rises steadily above it.
• If I switch the HVAC on both radiator fans run.
• When I run FAN 1 VCDS output test, both fans spool up, seemingly at a gradually increasing speed, to a maximum of 87.5% load.
• VCDS reads coolant temperature, it got to 101 deg C with no fans turning on (AC Off) before I switched the car off.

 

Can't work out what's going on.  The car seems to know the temperature of the coolant, but doesn't switch on the fans.  Fans SEEM to work ok, because AC turns them on.  

 

Is there something else apart from the coolant temperature reading that turns on the radiator cooling fan?

 

Thanks heaps.

Cam

I should add, normal driving is fine, no overheating. Normal temps indicated.  It's just when sitting in traffic that the temps climb and the fans don't come on.

 

• What temps do the fans normally come on at?
• Is there more than one coolant sensor?  I'm wondering if I'm getting a reading off one (say the pump one) and the radiator one (which might be the ones the fan use) might be no good?

Thanks