I get good heat from the climate control system when the control is set to 'Hi' temp. Anything lower than Hi is cool......selecting very low temps gives Ice cool air so I believe the cooling part is working fine, was great in teh summer too. But now it's colder I am selecting heat...I believe the pump is working and I can hear the valve? working....anyone have any obvious pointers or starting points, anyone seen this problem before?

Thanks, Allan

 

I'd like the hear discussion on this as well, Allan.

Is this a new development for you, or has your system always given weak heating?

The heating mode on my X300 has always been weak .....my complaint sounds essentially the same as yours....and I *think* X300s and X308s have the same system. (Can anyone confirm that?)

To clarify......

The climate control doesn't seem to respond well to very cold cabin temps. With the cabin temp below freezing, the system set to "auto" and 75ºF, I would expect some seriously warm air. What I get is somewhat warm-ish air.

If I *really* want to warm my toes I have to manually drive the desired temp setting artificially high....to 85º or so, or, as mentioned, to the "high" setting. Then the system pumps out hot air like crazy. Nice.

When the ambient conditions are moderate or merely cool-ish I would expect the system to just 'gently warm' the cabin . That's fine, and that's what the system does. However, when ambient temps are outright COLD I'd expect the system to ....um....make a more sincere effort to heat the cabin....without being browbeaten into submission by me driving up the settings.

Over the years I've heard from several others with the same complaint.

Is this a correctable fault or just a design weakness that we have to live with?



Cheers
DD

 

Very topical given the time of year

For "acceptable" cabin temperatures, the temperature setting I use is 80*F. This is compared to 75*F that it sits at in the summer.

At that setting, the drivers' footwell remains colder than desireable as I like to drive with the window or sunroof cracked open and I like the lower body warm while the upper body is cool.

The drivers' footwell duct on mine is cut back to avoid fouling the tip of my right shoe. But I noticed when doing so that the duct is not much more than a token as compared to other vehicles.

There are two things I suspect.

1) the Jaguar system runs the air compressor at all times to dehumidify the air. the only times it does not do this is if you override using max or kill the compressor using the dash switch

2) air leaks around the pedal box, steering column, wiring openings

When domestic vehicles used to just dump the heater flow through a flap over the centre tunnel everything was great. Then came consoles and individual ducts. Still, they did better than what Jaguar does. Indeed most cars have been better with the exception of the old Saab and Alfa coupes. And they didn't need auxillary heater pumps to do it either.

 

Try testing the system as per this pdf and let us know what happens. The operation pdf tells you how it's supposed to work.

 

Good and correct observaton. I think I could live with the diminised volume of air from the small-ish ducts if the air was warm enough




Right, the air is refrigerated and dehumidified first, then heated as necessary.

Naturally, then, one wonders if the "heated as necessary" mode is functonally properly. In my case....I don't know. I have no climate control trouble codes but that isn't proof positive of correct operation




Worth checking, and would account for cold toes, but I don't think it would explain why output air is merely warmish when we'd like somethig closer to hottish....unless the leak was bad enough to really chill the ductwork and draw off the heat






Ths isn't the first automatic climate control system that left me disappointed. Others have given lazy response as well.

OTOH my elderly Ser III XJ6 had a terrific system which operated in a logical manner. If the differential between cabin temp and dialed-in temp was large the system would respond with gusto, giving hot or cold air and high fan speeds. If the temp differential was small, the system adjusted cabin temp with merely warmish or coolish air and low fan speeds.

'Tis the 'gusto' part that the X300s seem to lack

Cheers
DD

 

https://www.jaguarforums.com/forum/x...nfo-faq-66454/

More good info here. BTW, I have 2 jags and love the system on both. Now if you want to talk bad designs, look at any BMW out there..........

 

Thanks for the addt'l info, Rob.

At first blush the diag info looks to be the same as what I've seen in my X300 manuals. I'll do some more comparing but I think the X300 vs. X308 systems are essentially the same.

I'll add, in agreement with some of the other postings, that my system does well in *cooling* mode.

Cheers
DD

 

I just set mine to 22 degrees C and leave it there, works great on both cars.

 

As the heater core gets older, it gets blocked and becomes less effective. I still have heat, but not as much as I used to. A heater core flush might help.

 

Interesting point in the operation pdf about the ghost mode for the heated windshield. Never seen that mentioned anywhere before.

Those wanting to know will have to read the pdf

 

That's an interesting point. I have never actually reached down there to feel the outlet air temperature. I must try it. Tomorrow's grocery run should be good. It's supposed to be -5*F.



Well the heated as required should be controlled by the cabin air temp sensor which should drive the heat valve or blend door open to maintain the selected temperature.

What if you run with the AC compressor off for a bit. Feel a difference?

Maybe the temperature sensor location is not ideal and of course it has been reported that us smokers clog the sensor with contaminants. On the X308 it is down by the left knee in the instrument panel. What if the electronics behind, or indeed the closed off panel is keeping the sensor warm while we freeze? Moving the sensor down to the floor area by extending the wiring might be "the thing to do". Electrically and mechanically, it is an easy diy. Cosmetically, it might be a bit more challenging. You first


Without having checked the actual outlet temperature, I was suspecting a draft of cold air defeating any heating.

The heating controls are far too complicated. The S-Type looks like it has the big 3 round knobs which I favour from the past.

GM mechanical sliders weren't too hard to figure out either. Even though it wasn't a auto system, you pretty soon learned how to feather the controls.

 

Yes, but if the air coming out of the side vents is boiling hot ... it's not the heater core.

We would just prefer that it come out of the footwell ducts.

 

Great idea. I'll give it a whirl.




Hmmmm.

Maybe.

Despite my wordiness on the topic this really isn't a big problem for me. Pushing the buttons to get the desired result isn't very hard. With a manual control heating-A/C system I'd be doing the same thing and not thinking twice about it.

If this was a known-correctable fault with an easy fix, I'd probably go for it.





Cheers and thanks
DD

 

Well manual or not, I'd like a sauna in the footwells.

Heat rises, and my habit is to drive with the windows at least partially open. If the footwells are warm, it's quite comfortable and refreshing. It used to be a necessity to keep the windows from fogging. But now Jaguar wants to run the AC to do this and deprive me of warm feet in the process

 

Ran some errands and experimented a bit. Turning the a/c compressor off made only a slight difference. I forgot my HVAC thermometer but I'm guessing the output air was maybe 2-4ºF warmer....just enough to feel.

Cheers
DD

 

Hi Doug, sounds exactly the same symptoms to mine......Didn't think your descriptions were wordy ('wordiness') by the way...right on the money and clear, resonated with me.......thank you....Allan

 

Sounds strange that the climate system would refrigerate and then heat the air...seems like a waste of energy and not to mention the environment...anyway. Like Doug I get very hot air when set to Hi, not much else when selecting other lesser temperatures.....the vents all seem to put out hot air when set to HI...so I can't help thinking it's a temp control or controller issue..... When in hi mode, does the system turn off the A/C pump by any chance - I am trying to work ot what's different about selecting Hi, as opposed to other temperatures.....Anyone solved it other than a matrix flush and pump change? Thanks, Allan

 

I have noticed the the incoming air is not as warm when in the auto mode on both of my cars, so I only use it occasionally in the winter to keep the pump lubricated.

 

Pretty common, actually, on climate control systems. It's done to dehumidify the air. That's why you never see a Jag driving around with the windows all fogged up






I agree. But I'm beginning to think that it's a design weakness rather than a repairable fault.

Was there a time when your system behaved better? Or has it always been weak? That would be an important clue.





No, not on mine, at least. And, as mentioned above, manually defeating the compressor makes little difference


In the max settings, either hot or cold, the automatic temp regulation capability is defeated. As far as I know.

I'll do some more reading today in an attempt to clarify a few things






I don't think either of the above would do anything for us because we know that the system CAN produce hot air....which, IMHO, wouldn't be possible if the matrix was clogged or the pump inoperative.

One of the earlier posts links to a previous thread. One of the posts in *that* thread has all the testing info. I would sugest that you check your system for codes (easy) as a first step. Maybe in your case there will be an actual identifiable failure that can be corrected.

Given how often I've heard this complaint about weak heater performance I'm really leaning towards a "that's just the way they are" conclusion. That is, the system is intentionally programmed to heat the cabin very gently.

Either that or an awful lot of us have the very same fault.

Cheers
DD

 

I've been reading both my X300 service manual and the X308 "testing" document (post #4 above) and I'm not coming up with much. There's very little by way of DIY trouble shooting. Diagnosis relies very heavily on the presence of trouble codes and there's an awful lot of "refer to PDU". We're not shown resistance specs for the temp sensors, for example.

I did learn something new. The heater valve operates on a duty cycle to continuously control the amount of hot coolant flowing into the heater matrix. On the oldie Jags the heater valve was simply closed for max cooling and simply open in all other modes.

At first blush I thought I may have been onto something but, in thinking about, no. The fact that we CAN get hot air suggests the valve is A) electrically operational and B) isn't mechanically stuck closed, and C) not clogged. If the valve isn't letting enough hot coolant into the heater matrix it would be due to a control issue and not a fault within the valve itself.

Absent an epiphany....mine or someone else's.... I think I'll throw in the towel and merely continue browbeating the system to give heat when I really want it

Cheers
DD