My Climate Control seems to lose it's mind occasionally.

I pretty much keep it set on auto with the temp set on 73-74 degrees.

Tonight while driving along (the cabin was warmed up and comfortable) all of the sudden the blower started going full blast and the temp out of the outlets was full cold.

I tried to adjust the temp setting all of the way up to 90 to see if it would at least blow warm air. No change in temp out of the vents.

I switched to the Defrost to see if that would help. Airflow went to the windshield but it was still freezing cold.

After a few minutes the warm air came back on it's own.....

Anyone ever heard of this or seen it happen????

 

Anyone?

It did it again tonight on the way home from work.

It's as if the thing is switching from a calm gentle heat to full blast A/C for no reason at all.

 

Are you getting any of the climate control codes?

The climate control system will display codes on the display. Here is a link to some information on the codes. Look, alphabetically, for 'Climate Control'.

https://www.jaguarforums.com/forum/s...ad.php?t=29800

 

No codes at all that just pop up. The display reads the 73 that I set it on.

Is there a diagnostic mode?

Edit...

I just read the document. I'll do the test and get back to you.

Thanks!

Ken

 

Ok I got two codes...

14 - Water temp. input malfunction Instrument cluster output. Refer to PDU.

44 - Defrost vent motor harness/connector fault servo motor seized or sticking flap seized or sticking refer to PDU.

First what's a PDU???

Second, are these typical problems?

Thanks,

Ken

 

PDU is the diagnostic system that the dealer uses.

If you will go to the JTIS OBDII code list you will find the codes and a list of issues that will cause them.

If you do not Have JTIS it is available as a download here:

https://www.jaguarforums.com/forum/s...ead.php?t=9933

 

Ken,
I am certainly no expert on the topic, but my XJR used to do almost the same thing, except I don't recall the fan going on high all on its own. The fan would only go to high when I turned the heat up on Auto, which makes sense. It used to start blowing at outside air temperature. In Calgary, that is not usually too nice in January or even this time of year. It was as if it had a mind of its own and would do it for a few minutes, then return to normal. This winter, I drained my cooling system and carefully refilled it according to the JTIS manual. That seems to have taken care of it. The XJR refill is a bit more complicated,with perhaps more of a chance for air to be trapped, but maybe that could be it with your car. I think there must have been a bit of air that caused it in mine. I had the cooling system flushed and changed by the dealer about 3 years prior and it did it for those 3 winters intermittently but not often enough or long enough for me to do anything about it. (happened once or twice weekly - never lasted more than 2 or 3 minutes) I have paid attention to it this year, but since re-filling the system upon timing chain replacement, it has not happened. I know you changed your chains recently, so perhaps some air is trapped. On the other hand, I never checked the codes, but with luck maybe yours could be that simple. Perhaps that 14 code could be triggered by the cold air resulting from an air lock? The 44 code seems a bit more worrisome though. Maybe a re-boot will take care of it.

Let us know how it goes... but spring is coming! Now that I have said mine was rectified, it will probably do it again tomorrow.

Wayne

 

Wayne,

Still kind of cold here in Detroit too...

Your point makes a ton of sense....I'm going to read up on refilling / topping off and see if that solves the issue.

BTW it did it again at lunch today...I did figure out that if I switch off the a/c and auto and run the system in manual that keeps it at a nice temp.

Thanks for your input!

Ken

 

It sounds to me like your heater valve may be starting to fail. My valve failed and I only got cold air (even through winter last year). I tested everything and ultimately took the pump out and bypassed it. I have extremely hot air now, but I can't modulate it. I am getting a new pump this weekend and will replace it. It may be that the valve is closing off the hot water intermittantly causing you to blow cold air. I don't know why the fan would kick to high though. It isn't terribly difficult to pull the valve out to bench test it. It is below the collant filler tank on the driver's side.