The resistor module controls fan speed, not temperature.

 

Well, then it's not (only ?) that module...because the temperature doesn't seem to change. And, actually, when I turn the temperature all the way down (even below the said "range" mentioned in the OP), it stops blowing altogether...tough to pinpoint where that could come from.

 

Time for a specialist?

 

I guess I'll have to pay a visit (before paying something else...) to the local Jag dealership, indeed...

 

A little update on this issue...

So I brought it to the local Jag dealership to have it fixed, having tried the suggested DIY approaches without success.
It was indeed the blower motor and resistance module that weren't working. They changed them and now the A/C works fine...except...now it pees in the passenger footwell instead of under the car!

I got the car back on Friday afternoon, the flooding of the carpet began the very next day (without rain) and I had to leave a fan heater in the passenger footwell for a few hours to dry it all. I also drove it a bit yesterday (Sunday) and, again, water was running down there.
So I brought it back to the dealership first thing in the morning today (Monday), telling them about it. One guy from the workshop said it may have been water leaking in, as the motor they changed was all rusty. To which I replied it can't be, as I had experienced no leak of water inside the car before, but that it used to pee underneath the car before and now it does inside. So it has to be A/C condensates no longer finding their way out.

I don't think it could be the duck bill (unless they changed it but I don't see why they'd do that), because I had never experienced that issue in 1.5 year of ownership (don't know if it had been severed to let condensates run more smoothly, though) and it would be a fantastic coincidence that it would get clogged right at the same time I took the car there... So my guess is that they messed up something (fitting a pipe badly or pinching it...) when mounting the new blower motor on the car. What do you guys think it could be?
Come to think of it: could it be the duck bill that got clogged, causing the water to overflow, that resulted in that motor dying?

Anyway, now the car is at the dealership, with no guarantee as to when I can get it back (I told them I absolutely need it on Friday morning though) because this time unlike last week I had no appointment... I'll keep you posted anyway.
But this is such a pain in the butt, frankly...

 

Yes

 

Oh sh*t... So that motor is on the "usual" path of water when it overflows from the duck bill, then?

But then something is odd: how come no water was dripping into the passenger footwell before that motor was replaced? I don't get it...

 

Maybe some crud got dislodged when the motor was changed and found it’s way into the duckbill, fully plugging it. Must have been a slow duckbill previously, backing up with water and getting the old motor wet so it rusted.
Slice off your duckbill and be done with those water issues.

 

The problem is that now I've left my XK at the dealership and told them to fix the issue...but I sure don't want to go 'the dashboard removal way' when I can do it with simple tooling...

 

Typically, the fan motor and module are ruined by water not draining properly through the duck-bill pipe ends. And typically it is water on the passenger side floor that is the first sign. In the case of my XK this was the pattern: first the water on the floor, then two weeks later, failure of the fan motor and module. In between these two events, my dealership, by my instruction, did NOT dismantle the dash. They lowered the transmission to give access to the duck-bill ends, which they simply cut off. The result was that water freely exited under the car as designed. But unknown at that point was that the fan motor and module had already been damaged.

Lowering the transmission for access to the drain hoses was an easier path. Problem solved. Replacing the fan and module does not require dashboard dismantling.

 

Thanks for sharing...but in my case I didn't have any water in the passenger footwell before the blower motor died. Which kind of makes me not 100% sure it was the duckbill in the first place...

 

I think the motor gets wet before you get water on the floor, otherwise the motor wouldn’t get damaged as the water would leak onto the floor only. You may have just been lucky in the past with low enough humidity and short drives such that the water never overflowed onto the floor.
My duckbill issue didn’t occur until a fairly lengthy drive on a hot summer day. So I was probably having some water backup previously but not enough to overflow, until that first long drive on that hot humid summer day (sure surprised my wife when it actually happened!).

 

The resistor will fail with age, regardless of water. Fan bearings can fail as well, as did mine at a young age, without water, but a rusty fan likely means water. I doubt the specialist caused the water back up.

 

Based on you guys' feedback (big thanks to all of you!!), I've decided to call to take the car back tomorrow, hoping they haven't started working on it yet (no appointment this time, and they told me they didn't know when they could take care of it). Then I'll do the duckbill surgery to be rid of that problem, once and for all I hope.

Speaking of which, by the way...how far from the tip do you recommend to cut it? At the bottom of the funnel?

 

I sliced off what I could reach, sight unseen, but I got 1/2 to 3/4 of an inch off:

 

Anything off past the flat part, and Bob's your Uncle.

 

I have borrowed my brother in law's endoscopic camera tonight. I'll have a look tomorrow when the car is cold. Right now there's a fan heater in the passenger footwell to dry the carpet...

I have thought of one possible scenario: they may have replaced the blower motor and, meanwhile, removed the whole duck bill, to make sure it leaks and make me come back to have the whole dash removed.
That would make them crooked b*st*rds, but it still could be possible...I guess.

Hence the following 2 questions:
1. If the whole duck bill is removed, will water leak into the passenger footwell or will it run underneath the car, as normal?
2. Can the duckbill be accessed (and removed) when the blower motor is removed?

Thanks for your answers guys!

 

Hey George. It's not likely that a she would use our DIY procedure on the duckbill. You can lower the transmission a bit to access it and it's doubtful they did that if their goal was to repair the motor.

 

Can’t get to it from the location of the blower. Either from the right engine compartment if your hands are small and your arms are long, or perhaps a stick with a razor blade as some have done or drop transmission.

 

Thanks guys for your answers.

@ Sean: what I suspect is that they may have done that (removed the duckbill) to create another problem so they can "fix" it and make me pay once more...and a hefty price at that, given it would require removing the whole dash...

But just to make sure: would water get into the passenger footwell if the duckbill is off?