Hi to all.I own a td6 with dual zone a/c system.Although i have changed parts such as thermostat,all sensors still heating reacts as it likes.In order to have hot air i have to push on/turn off system more than two or three times while both temp switches must indicate max heating temp.But problem not till here since if min temp either at driver's or codriver's side even by 2 degrees,from max hot temp, then hot air stops and instead starts to blow cold.
During summer time a/c blows cold air but i donot think that temp of air is increasing/decreasing fm switches.
So now i am thinking if problem has to do with defective heating control panel.
However since i have changed parts in waste of money/time wondering,before start looking for a new heating control panel,if is possible such problems to be because of defective control panel and if there is any way to check if is faulty or not.

-Workshop has given up/cannot find where is the problem

Any suggestion will be most welcome

Best regards and congratulations to all you guys for the best job u do in this site.

Workshop not registering any faults with the A/C Heater system ? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
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MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

I had similar symptoms on my old P38 and had to replace the ECU. ----------
2014 tdv6 (ex. 2004 td6, 1997 2.5 dse)

Unfo workshop can see not any fault.Wondering if was ECU wouldnot be possible to be read?????

From a look i just had ecu is integral part in heating control panel.But wondering if any way to test it?

Have a look online for the Workshop Manual of the L322, it is in PDF and is for the 2002 to 2005 model year like yours. Then go to the A/C/Heating section and have a look at the various valves that direct the warm/cold air flows. It could be the actuators or vacuum hoses controlling the valves that are giving you the problems.

You have to remove parts of the lower dash, glove box to get access to one of them and then you can see it move.

If the ECU is faulty it is likely that there would be problems reading it although it may still have an issue that is not affecting diagnostics or generating fault codes (small chance in my opinion but still).

Have you played with the face level temperature settings ?? Is there any heat near the feet, in the back ???

Good luck. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Thanks your replies.By the time will start blow warm air all seems that are in order.i have lower/upper/face/back heating provided that i will not try reduce temp from full either from driver's or codriver's switch.So till this stage i guess that valves/etc normally work.But still i donot know if change of temp has something to do with vacuum hoses controlling the valves or valves.is this possible?To me heating system seems to be very complexed with too many stuff and unfo i understand very few thinks.

AFAIK the dual zone is controlled by two solenoid valves in the engine bay, one for left and one for right hand side. maybe these have become faulty? they are between the inner wing and the engine on the right hand side as you look into the engine bay, they open to let warm water into the heater matricees inside the car. There is nothing that can't be fixed with a hammer😜😜
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