Heater booster

[maysani]

At which temperature the heater booster can be activated, I was under the impression that it get activated when the ambient T is 5C or below. However, we had a mild weather recently and the heater booster in my TDI 2003 Galaxy gets activated eve  11C, is that normal?   

[SilverBeast]

The MKII gets activated at around 10C, I understand the MKI was around 5C.  Mine comes on about 10.5C from the climate/dash display.

It uses a different sensor (clipped to the back of the wiper mechanism, just in front of the  filter on the heating air intake) to the one in the dash/climate display (visible through the lower grill next to the front foglight on the passenger side) and is just an on/off sensor.

[Mirez]

As above, officially its 5*c for Mk1 and 10*c for Mk2.

In practice it seems the sensor isn't exactly calibrated though as the heater has been known to fire right up to 15*c in some cases!