The car is an 2004 Super V8.

The heater gives uneven temperature at different vents:
Driver side (left, LHD vehivle):
Footwell vent: hot
Dash vents: lukewarm
Windshield defrost vents: cold

Air volume at the vents is sufficient (not restricted), just the temperatures are different.

On the passenger side (right) it is better but the windshield defrost vents are still not as hot as the lower ones.

We flushed the heater core with citric acid solution and tap water back and forth with no success.

Any ideas are appreciated.

 

Hi mrvip,

I have to head to work so I can't look up any links for you, but if you will use the advanced search function to search the forum for "auxiliary heat pump" and "heater matrix" I think you will find some relevant information. Your pump may need new brushes, or worst case, to be replaced, or your heater matrix may be partially blocked.

Cheers,

Don

 

As Don has said it will be the aux pump or heater matrix.

I doubt that citric acid would shift a bockage, it's sticky and gooey.

 

Are the vent actuators functioning correctly? Moving the doors appropiately?

 

Anyone ever try OxyClean (dye and scent free) to get the sludge out? I use it to clean lots of items especially in my home brewery. Seems like it would be better than straight water. Mine is blocked, and just waiting for some nice weather and the citric acid comment got me thinking about a cleaning additive.

 

Thanks for the replies.

I have researched the pump and the matrix topics before posting. Pump seems fine, and most folks on the heater matrix threads resolved their problem with a simple flush + Steradent. I've used citric acid, as per Mercedes-Benz's protocol for flushing cooling systems, which is stronger than Steradent.

What's more important is that almost everyone complained about left to right difference, but I didn't see anyone complaining about top to bottom one (hot air in the footwell and cold air on the windshield.)

Regarding the vent actuators my understanding is this:

There is a cold/hot blend door for each side and then distribution doors for the different vents.

I can understand how a partially blocked matrix could give heat to one side and less to the other, but I don't understand how it could make a top to bottom difference in the same duct and likewise i am trying to comprehend how a malfunctioning blending door could produce different temperature "streams" in the same duct, which then are separated by the distribution doors to the different vents on the same side. I guess the fact that air flow to the corresponding vents is normal and starts/stops according to the A/C display setting means the distribution doors are working properly?

We didn't try to access any blend or distribution doors yet, but they seem buried quite deep in the dash and i prefer to gather some opinion beforehand.

 

Thanks for the additional info, mrvip,

The wording of your original post led me to assume there was a difference in temperatures between the "Driver side (left, LHD vehicle)" and the passenger side. I apologize for my misunderstanding.

I haven't studied the X350 blend door function, but typically at least one set of blend doors apportions air flow through the heater core and A/C evaporator to provide continuously-variable air temperatures between maximum hot and maximum cold.

I'm sure there's some service documentation on the system. You might start your search with the Body section of the Workshop Manual and the Electrical Guide, which you can download at the links below:

Table Of Contents

General Information

Chassis

Powertrain

Electrical

Body

2004 X350 Electrical Guide

Hopefully others will have some more specific information to share.

Cheers,

Don

 

I would suggest that you remove the aux pump and bench test it with water since I am sure that

you will be aware that the pump could be turning but not pumping, or pumping but not

pumping enough.

The climate unit is a large plastic box which contains the matrix and the blend

doors. There are ?seven motors attached to both sides of this box which move the blend doors.

The motors and assoc. linkage are visible on the glove box side with the glove box removed.

Faults with these motors are very rare on the Jag but there has been one where some internal

foam became detached and one electrical fault with a wire.

As it happens there is a fault with the operation of a blend door on our VW and when my son was here

for Xmas (he lives in NC now on your side of the pond) he tried out his new VAG scanner and it recorded

a DTC with a blend door motor ! I was amazed since I did not imagine that there would be a sensor but

the system must be monitoring the current.

It might be worth looking for a DTC on your Jag.

Cheers

 

Good post!

I have a similar fault:
On the left side, the climate works fine, even with AC on and off. On the passenger side, with AC on, it works ok and is only sometimes warmer in the leg room. If I switch off AC, the leg room gets warm to hot air, even if heating is set to lowest value. Looks like one blend door does not close enough.
Can I enter this one via glovebox ? Does anyone have a picture? I'm on holiday and do not have tools with me..

 

Silting-up of the heater matrix is a known issue with these cars, and I recently had mine replaced to restore heat. It is not a cheap job at a main agent, but my invoice had 3 hours labour for the job, which is not all that long. However, I finally managed to find the job description in a very large workshop manual file which shows the job is not huge. Replacement involves draining coolant, then removing glove box and heater fan module, at which point the matrix is accessible. Actually the parts on my job came to quite a lot as there is a fitting kit as well as the matrix.

 

All you can do IMO is to watch the actuators on the side of the climate 'box" and see if they all work when someone presses buttons.
You can see one side by just lowering the glovebox but I don't know about the other side.
If there is a fault inside the box that would be a big job to remove it.

https://www.ebay.co.uk/itm/2006-JAGU....c100005.m1851

 

Hi Elegancec,

Just to be sure that replies are relevant, what is the year, model and engine of your Jaguar? It's helpful to add this information to your signature so others don't have to guess or ask.

Cheers!

Don

 

My 05 Super V8 has exactly the same uneven heat distribution that you describe in your post from 2017. Can you tell me how you got it resolved?

 

Hi, I could not solve it sadly.

Looks like some foam to close the door is gone.

 

This is the first time I have seen someone with the same problem as me. Both drives and passenger footwell are nice and hot. Drivers side face vents are cool but passengers are not much better but there is heat on that side and the screen vents are both cool. I have a cheap endoscope from lidle so I may shove the camera down the vents and see what is happening.

 

That's the right description, footroom passenger side is hit, face vents medium, screen cold..