On my 09 Xk 5.0 when engine cold if I press the def button fan turns on full and blasts air into footwell however after about 1.5 miles then the windscreen vents start working. So with engine hot works as expected however if I stop for 10 minutes then restart and press the def button again no air on windscreen just the footwell but after 1.5 miles the windscreen vents start working. All a bit strange, is this normal or is there something going wrong ?

 

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I keep my XK garaged so DEF isn't normally required but I tried it on a sub zero morning yesterday.

On a cold start:
1. front and rear screen heaters come on
2. engine RPM elevated for over a minute
3. blower running BUT no output from any vents
4. engine revs drop to normal (after initial "fast" warm)
5. screen vents open

All air is directed to the screen; nothing to the footwells.

I think this is normal operation and certainly seems logical although the 2014 Owner's Handbook makes no reference to DEF other than the drawing showing the button location.

Graham

 

I’ve not heard of the deflector actuators becoming worn on these cars, yet. but they are getting up there in age.
Certainly have heard about the complicated replacements of actuators on other vehicles…. typically the dash has to come out.