My XJ has a strange A/C problem with which the local dealership seems clueless. They have tested the system and claim that everything is fine.

However, the system is not able to hold temperature. In hot weather there is cold air flowing but the flow is insufficient to prevent interior temperature from rising. The same when it is cold - Windows easily get slighty fogged and the interior temperature drops. Hence, I am forced to use manual control to boost the air flow to a sufficient level.

Manually the ventilation (propellers) work fine and the actual A/C unit produces hot and cold nicely because the systems works fine when controlled manually.

Does anyone have any ideas what could cause this? Perhaps a malfunction in the control electronics or sensors?

Kent

 

Two things you might look at. One, is your cabin air filter being replaced at the service interval recommended. And Two, in Climate settings I set it to maximum and it seems to hold temp settings better.

 

It seems that changing the Climate settings improved the situation a lot.

Thanks for the advice!

 

What does maximum do? Maximum what?

 

From the manual:

AIR QUALITY SENSOR
If the air quality sensor detects pollution, air
recirculation is selected automatically to
reduce pollutants entering the vehicle.
The sensitivity of the sensor can be adjusted
using the touch screen:
1. Select Settings from the Climate menu.
2. Touch the +/- buttons on the screen to
increase/decrease sensitivity.
To switch the function off, decrease sensitivity
to the minimum setting.

It worked for me too to improve cabin comfort

 

Increasing sensitivity makes it work better?

 

Works for me as my original complaint to my tech was similar to yours as the temperature fluctuation was high. He said try this setting and I've been happy ever since.

 

amcdonal, think of the sensitivity as to the error that the climate control will allow before it makes an adjustment to provide more cooling/heating. If you set the sensitivity low, it may allow the temp to vary by say 5F from the desired. Where, if you dial the sensitivity up, it may control it within 0.5F. The trick is, the more sensitivity you have, the more the components are going to move to maintain the temp. So, in theory, you are going to wear out the components faster leading to higher maintenance costs.

 

Ah, I thought the sensitivity setting was for the pollution sensor.

I wonder if the XK has such a setting but I doubt it. Sometimes my climate seems to do odd things.

 

As XJsss brought to our attention in post #5 above, the sensitivity setting was for the pollution sensor. Having no idea what pollution problems exist in Stockholm, (i.e. diesel belching trucks and buses), it sounds like a reasonable suggestion to me.

 

I have a 2007 XJ8 that had same problem I took it to the dealer (way to much) then took it to my local guy and he told me the valves on the compressor were bad (I believe 2 of them) bill 120.00 never have had another problem with A/C. Hope this helps