I notice every so often that my A/C is no longer on "Auto" - which is where I always have it. I can't tell you exactly how or when it happens, but I will notice every so often that the red light on the Auto button is not illuminated and the A/C is running on "manual." Of course, it could be due to me accidentally hitting the fan knob or something that switches it from "Auto" to "Manual," but I can't believe that that's what's happening.

So, the question is this -- is this a "typical" issue that others have experienced and something that I can either fix or at least something that others have figured out?

It's not a big deal, it doesn't happen all the time, but if it's not something that anyone else has ever experienced, then I'll chalk it up to my fat fingers!

Thanks, and I tried to search for it but didn't find any threads on the issue -- if it's been discussed before and you know where, please point me in the right direction.

Mike

 

Do you ever adjust the fan speed, or select where you would like the air to flow (defrost, vent, floor, etc.)? Doing any of this will set the climate control to manual controls.

 

if you lower the temp below a certain amount it will take it off auto as well, I don't remember how low you have to go but try sitting in your car and as you lower it you will see the auto light go off at some point below 70 degrees F

 

Not intentionally! I know if I do those things it will switch to manual. Seems like it goes to manual without doing those things. Could be my imagination. I'll keep an eye on it. Hasn't happened since I've been more careful.

 

When my wife had her 99 Toyota Sienna, she thought the van had an electrical issue because the radio would randomly change stations for no obvious reason. One day, while I was driving it, the same thing happened. That's when I noticed that the side of my hand was bumping the steering wheel audio control, which just so happened to be placed exactly where I rest my hand on the wheel. Never could convince her that nothing was wrong with the van, though... lol

 

I do know that, on occasion, I've turned the fan knob to raise or lower the radio volume!

 

My A/C was switching from auto to manual by itself about a year ago. I checked the A/C codes then cleared them, and the problem was fixed. I think I had a code about a potientiometer or something.

 

I would have to find someone who has the right code reader, right? Or aren't you talking about OBDII codes?

 

Here is how you check the codes.

https://www.jaguarforums.com/forum/x...20/#post199495

It doesn't require a reader.

 

Mike, ther is a sequence you can go through to check for codes in the A/C system.
The Denso unit also has a facility where it will switch off if the system pressure falls below certain parameters.
When was the last time you A/C system was tested and re-gassed?
Have you replaced the receiver/dryer?
This should be done at the same time as a re-gas.

 

Now THAT'S some great info! Thanks!

Mike

 

There is also a Youtube on charging the system using the AC PRO kit in a XJ8. Takes about ten minutes, mostly in removing the plastic shroud between the firewall and throttle body -- I didn't bother with replacing the drier, all worked fine afterwards and I can freeze meat on a 100* F day.

 

My AC works fine --- coldest AC I've ever had in a car!

 

I've done that too Mike!

 

Ok, finally it happened when I was positive I hadn't pushed or turned anything -- twice it happened on the way to work this morning, went from auto to manual.

Now I'll try the self-test instructions and report back later.

I was hoping that I was just going bonkers and there was nothing wrong with the AC!

 

I got two codes, 14 and 45. Any suggestions?

14 Water temperature input malfunction Instrument cluster output Refer to PDU

45 Centre vent motor fault Harness / connector fault Servo motor seized or sticking Flap seized or sticking Refer to PDU

 

Mike run a reset then another self test when the car has been running, say when you get to work. See what it reports then. I think the 45 will go but unsure of the 14.

To tackle that....
Another thing to check is the aspirator fan assembly for auto climate control with interior temp sensor. Take the little grill off and with low pressure compressed air clean the aspirator - pc keyboard canned air works well - located where the interior trunk switch is. Use plastic to save damaging trim.

Hope that helps

 

I just did that today! LOL

I am also REALLY good at hitting the Valet button instead of the seat heat button.

 

Thank you, but I have two questions.

First, is your "to tackle that..." comment for code 14 or 45?

Second, can you be more specific about accessing the "little grill?"

 

I meant 14 - the grill cover pries off with stiff plastic implement tool or some such thing as not to damage the surrounding dash, behind it is a temp sensor to relay cabin temp and a little fan to draw this air across it - if the sensor is covered in crud/dust it will give you issues. If you do a search for it, there's been postings on it before. A 10 min job.