2007 XK Coupe.
My A/C was working fine, at max actually, during a hot day and a very humid period during a downpour. The next day NOTHING. The A/C controls on the dash screen appear OK, but nothing functions. No blower, no compressor. No air from the vents. I am thinking a fault in the computer. I have verified good fuses in F34 40A Orange, Blower motor and F6 15A Blue, Air conditioning.
I also noticed while checking over the A/C I also may have developed a blocked air conditioning drain tube. There was wetness on the bottom dash cover of the passenger side, but not enough to be noticed on the floor.
Any ideas? Ordinarily, I might try to reboot the computer by disconnecting a battery post, but have been led to believe this is not a good idea on the XK by reading posts on this forum.

 

That possible blocked drain hose may have caused a short in the blower since you have noticed dampness near the blower housing. I'm not an expert so you may get some answers here from members that have first-hand experience with this known problem.

 

Not experienced it myself, since I have a later model, but others have reported that the water sloshing about in the A/C housing can kill the blower.

 

when you have a running engine and change the climate control to economic, ist there a change in the reving of the engine. If so, the compressor is working. In that case I would try disconnecting the battery first and wait for half an hour. You'll have to program the windows setup according to the manual and you'll notice that the engine will reset itself during the first miles of driving. My 2007 xkr convertible had a AC Waterproblem and lots of water gushed into the passenger footwell. The new drainage tube, 6 € worth, cost 750€ repairs but the blower that had shoveled the AC-water survived.
Since you're not risking anything, try the computer reset through the battery disconnection.

 

Actually, the A/C compressor is a permanently engaged variable-displacement unit, so it doesn't have a clutch that engages when you switch on the climate control. So there's never an A/C-related change in engine RPM to tell you that it's running.

 

Okay Ngarara, I just wondered why my RPM change occurs when going into economic or active mode. Its good to know that the airco is permanently engaged, thanks for the detailed info. Love to learn more about my XKR-baby. Perhaps the Rev-change is due to electric changes in current-load?

 

Could be the drain from the blower starting up, I guess. The nice thing about the permanently engaged compressor is that the lubrication doesn't gum up and the seals don't dry out during winter when there's not much aircon activity.

 

Thanks for all your help.
I did also disconnect the battery which did not change the A/C not working status.
I took it to the dealer (Jaguar of Albany, NY) today, who determined that the blower motor CONTROL MODULE needed to be replaced. The Module is on order to be installed next week. ($700 = labor and parts including diagnostic)

 

Ouch! I suggest you get them to check if the blower failure is due to accumulated water because the 'duckbill' drain tube is blocked. If that is the case, you probably need to get the drain sorted out too, or the water will just build up and kill your new blower. Unfortunately, that's a major job, because you either have to remove the dash or drop the transmission (the drain goes into a tunnel in the transmission casing).

 

^ What Ngarara said! Check it out or face the problem again in the future! There is a TSB on drain issue.

 

So? Just what happens when you go to the ECON mode? The a/c for sure does not put out cold air anymore. Just asking why when in ECON it, does not put out cold air anymore.

 

The Jaguar Denso climate control: the compressor cycles on and off in order to dehumidify the air - it is then heated as needed, or left unheated as needed to reach the cabin temperature selected. Pressing the ECON button disables the compressor (hence improving fuel economy a bit) and thus the air is no longer refrigerated - you are now getting outside air which can be heated to reach the desired cabin temperature but which cannot be cooled below the ambient temperature. This is clearly explained in your owner's manual.
Jaguar climate controls have worked this way for years and years since the old Delanaire days of the late 70's and 80's - except with that system you could not disable the compressor.

 

+1

 

It's odd; the owner's manual says that the A/C compressor can be turned off, but the workshop manual says it is permanently engaged

 

It does explain it in the workshop manual:

"When economy mode is selected by pressing the 'Econ' TSD soft button, the compressor current signal supplied by the ATC module holds the A/C compressor solenoid valve in the minimum flow position, effectively switching off the A/C function."

 

Ah, OK, so the compressor still spins, but it is set to its minimum swept volume.

 

There is no econ mode in my 2012 and I don't think there was one in the 2008.

 

On my MY11 car, there isn't an explicit 'Econ' mode - there's just a setting for A/C on/off. Off = Econ mode.

 

This is the exact wording from my manual. Page 111.

"When the air conditioning is switch off, economy mode is selected automatically. Economy mode turns off the air conditioning compressor and reduces power consumed by the climate control system. This will reduce air conditioning performance."

Don't know if this makes it any clearer, but there you go.

 

They should check the blower motor module. I've had three of these go bad due to the blockage of the a/c drain. I think it will short it out before it gets the motor or it has in my case. Easy test would be to "hot wire" the blower motor to make sure it runs.