Intermittent Heater Problem on C5 2.7 HDI
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  1. #1
    Tadpole
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    Default Intermittent Heater Problem on C5 2.7 HDI

    Had a big service including cam belt and water pump recently at 4 years/ 50k klms.
    We've now got 2 problems:
    • The heater occasionally fails to work, possibly when the engine cools off going down a long decline. Coolant level and temperature are normal. Possibly the internal sensor is obscured or dusty although that sounds too easy. Where is the sensor and any other suggestions please?


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    • Secondly the sound system fails intermittently - everything including parking sensor warning, CD, Radio. It all works for a stretch then fails for a couple of cycles then resumes. Any ideas?


    Any assistance will be greatly appreciated.

    Thanks

  2. #2
    1000+ Posts Ken W's Avatar
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    OK Speed,

    So I assume this is a 2011 C5 X7 with 2.7litre V6 HDI. When you say heater fails, do you mean the interior fan stops or does the temperature of the blown air drop when going down a long decline? If it is a temperature drop, then maybe, the coolant system hasn't been bled properly after the new water pump was fitted and there is an air bubble forming in the piping going to the internal radiator.

    With the sound system, it sounds like you are dropping a power circuit. I have just consulted my pdf copy of the 2008 C5 X7 Owners Manual. Have a look at F14 behind the little pull out panel in the glovebox which seems to power that stuff and see if you have power on both sides of the fuse. It could be a dicky fuse, fuse connector or the fusebox itself.

    Report back what you find.

    Cheers,

    Ken W

  3. #3
    Fellow Frogger!
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    The audio drop out is a not uncommon problem and was/is present in my 2.7 and 3.0, but less so in the 3.0. Citroen has been unable to find a lasting solution. Either pull the fuse F14 as mentioned above or switch everything off for 10 minutes or so and it all works again. If you go to a dealer with it, get them to contact Joe Patane at Citroen Aus (Sime Darby). He told me a while back that he/they have found a setting that is wrong and causes it, but it is only accessible through diagnostic gear. It apparently only affects cars with an amplifier in the system. On my first car, the 2.7, they swapped head unit, amplifier, and BSI all to no avail. Robin

  4. #4
    Tadpole
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    Default Heater Problem

    Quote Originally Posted by Robin Hoffmann View Post
    The audio drop out is a not uncommon problem and was/is present in my 2.7 and 3.0, but less so in the 3.0. Citroen has been unable to find a lasting solution. Either pull the fuse F14 as mentioned above or switch everything off for 10 minutes or so and it all works again. If you go to a dealer with it, get them to contact Joe Patane at Citroen Aus (Sime Darby). He told me a while back that he/they have found a setting that is wrong and causes it, but it is only accessible through diagnostic gear. It apparently only affects cars with an amplifier in the system. On my first car, the 2.7, they swapped head unit, amplifier, and BSI all to no avail. Robin
    Thanks for the ideas Robin and Ken,
    It is a 2009 delivery C5 Touring Exclusive.
    The heater problem is a failure to heat, fans and outlet volume seems OK just cold.
    It has done 3000klms since the service (including a quick trip Goulburn to Noosa return) so I assume an air lock would have worked itself out, particularly as it usually works satisfactorily and the level is correct. I've no idea how to chase an airlock. Looking at the header tank there are already 2 capillary lines which I'd assume are bleeders, possibly one from each bank leaving the heater out of the loop.
    Any thoughts on the interior sensor being suspect?

    Regarding the radio, that is the problem as you both seem to be aware of. I'd heard it may be a "software issue". Usually on a long trip once it starts to work it is OK for a day or so. Then it is intermittent, truly random. It never restores itself unless the car is turned off. I'll try pulling the F14 and see what happens. I had a very similar problem (all sound out) with an E39 BMW 540i and the mechanic advised the diagnostics identified the "radio module" ie just the tuner, not the amplifier. I nervously got one off ebay and that was the problem fixed.

    I've got a w'shop manual on the way and I've a scanner so I'll try that too. I think I'll get it looked at Continental Cars if it persists and I'm in that area. Both issues really interfere with the enjoyment of a very nice vehicle.

    Thanks for your thoughts, Gents.

    Gos

  5. #5
    Fellow Frogger! Clogzz's Avatar
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    Coasting downhill shuts the injection down, so a long descent by cold weather cools the engine very fast.
    2003 C5 2.0i AL4 205,000 km 76372389

  6. #6
    Tadpole
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    I think the heater problem is solved.
    It continued to work randomly so on a cold morning when it was offending I removed the radiator cap and topped it up to the very top with coolant (+500ml) and let it tick over for 10 minutes or so. I could see bubbles coming out of one of the bleeders into the header tank but aren't sure if that was significant, or the fact the cap was off did something to the relative pressures or what but since then it has not troubled us and we've done a couple of 100klm runs plus numerous short trips. Fingers crossed that was it - some sort of an air lock. I'd also noticed a couple of bleeder type of fittings on the firewall, black plastic fittings off aluminum pipes which could also be a/c fittings so I didn't touch them.

    As for the sound system that continues to be random, particularly failing on short runs. I removed the F14 and drove it a short distance - it bleated warnings that the park assist was inactive which means normally this circuit has power when the fuse is in place. Curiously after I replaced it everything worked. I'll try this again and see if it happens consistently possibly indicating some sort of reboot scenario that restores it.

    I'll update if I have any breakthroughs...

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