[StephenA]

Driving home in Kat's 9000 today the A/C decided to play games with me. The system is set to Auto and it has decided that if the A/c is running to cool the cabin off then the recirc option is always selected. I have tried several things but it insists on running the cooling with recirc on - if I boost the temp then it goes to heat (i.e. put air on the windscreen) and turns the recirc off.

Any solutions of this odd behaviour gladly received

Steve

 

[MikeH]

The system is trying to save you money,there is no point in allowing "fresh" unrefridgerated air in.If you do so ,then under very hot conditions you would never be able to reach the set temp'and the compressor would be running constantly with a resulting cost in power loss and extra fuel consumption.this is of course why you should keep windows and sun roof closed whilst using a/c

Mike

 

[billj]

It's not only saving you money, but the control system thinks that is the only way to cool the car sufficiently. i.e. it hasn't got the capacity to cool the incoming air to the temperature you have set, so it recirculates the already-cooled air so that eventually it will be cool enough.

I only see this occasionally, and only on really hot days. It is normal. I'm sure it's mentioned in the handbook somewhere.

 

[Paul D]

Interesting feedback.

>>I only see this occasionally, and only on really hot days.

Stephen,
Has Cheltenham been a hot spot recently - or are you on safary?

If not, maybe one of the temp sensors has failed, deceiving the ACC unit into thinking external temp is higher than in reality? Just a thought.

 

[sevenman]

From my experiences, with a faulty internal air temp sensor (it thought the car was always at 40C) the system works at full power, so the fans would be operating at their highest speed.

If that is what happens, and the symptons show no sign of abating when the car is obviously cool, that could be the problem..

 

[StephenA]

No Cheltenham hasn't been a hot spot and I dont think Birmingham can be describes as on Safari.

The A/c was only running at a slow speed but its never done this continually recirc thing before... even when it was very toasty outside.

I think I might have to do a recalibration of the system...

Steve

 

[Paul D]

A re-cal definately worth a shot.

If unsuccesfull check out your external temp sensor.

Happy hunting - and stay cool!

 

[MikeH]

Perhaps we are talking about differant systems,on my 92,9000SE turbo with aac,it is impossible to run the A/c without it being in recurc' mode,press the recirc button and the system goes to Economy ie; no aircon.
Jaguar XJ6 Mk11,same thing.
I have tried to find the 9000 drivers hand-book,without success,as I am sure it tells you in there that it only works on recirc'.
Tin hat is donned,fire away.
Mike

 

[StephenA]

My 9000 doesnt always run on recirc - it kicks in from time to time, often when I start the engine after its been standing idle for a while.

External air temp reported temp at 69 Farenheit and internal control was set to 70. If I take it upto 76 then it starts heating the car.

Its time to clean sensors and recalibrate units on both cars.

Franky the ACC is too clever - if I leave mine at 70 then it blows hot air in in the morning when the external temp is 68 and in the evening it blows cold air in when the temp is the same.... I blame the light sensor.

Steve

 

[MikeH]

When you go to get a price for a replacement so;ar sensor.the one on the top of the dash,take a chair,you will need it when they tell you the price,well over £200.

 

[nosignolife]

my 9oooCDE was "playing up" with the recirc illuminated, and I ended up grabbing an owners manual, it says that the recirc function will switch on to "rapidly" cool the inside of the car or " ... when their are significant traffic fumes.." Maybe Brum has a lot of Traffic ...
Seriously though, you can Program the Air Con so that the functions you require are stored in memory and then recalled each time you restart;

1) Select the desired functions
2) press and release Heated rear screen and <--> together simultaneously (the ACC display and LED's flash).
To Cancel any preset programming, Press "Off + Auto" together (the display and LED's flash again).

Davey