Calling aircon gurus...
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Thread: Calling aircon gurus...

  1. #1
    1000+ Posts
    Join Date
    Oct 2010

    Default Calling aircon gurus...

    The car: Pug 406 SV D9 (with BSI, but not CANBUS)


    The problem: Aircon not working (again)

    Cabin fans work + heater works. Neither toggling aircon button on/off, nor changing requested temperature will trigger aircon compressor.

    Peugeot Planet/PP2000 does not report any faults. Using PP2000 I can actuate the compressor, but the test doesn't last long enough to affect temp at vents.

    PP2000 also reports in Parameter measurements "pressostat input - pressure correct". Does this definitely mean that there is no issue with refrigerant gas pfressure?

    When this happened 2 years ago, Balki suggested worn/faulty ignition switch could be the problem. He was right - a change of ignition switch fixed the problem. However, because 3 wires (to single plug) were too short, I combined the best bits from both switches, so have always had concerns my 'hybrid' solution might fail again.

    Actions taken so far:
    1. Checked fuses (both in cabin and under bonnet)
    2. Changed ignition switch (new one was 13 squid from the UK - including postage! However must be Chinese knock-off, given that it was so cheap, and didn't come in PSA packaging...).

    Given that cabin fans work, and compressor can be triggered by PP2000, what are my options? Can I exclude faulty compressor and low refrigerant pressure? Can PP2000 trigger the compressor if the BSI relay or ignition switch is faulty?



  2. #2
    1000+ Posts
    Join Date
    Oct 2010


    OK, false alarm - problem solved (for now)!

    Realised that I hadn't rechecked the fuses since fitting ignition switch. Found that #32 (under-bonnet) was blown .Among other things, this supposedly controls Thermostat & Fan unit relay. Puzzling to know what this means, as the cabin fans were working normally, the engine thermostat has no electrical control (I hope!) and the cabin climate control was clearly doing the best it could (using the heater and cool outside air to adjust the cabin temp to whatever I selected).

    Didn't seem to work instantly - maybe computer takes a minute or so to notice the change and reactivate, but air con is now working. No doubt current outside air temp of 14C (same as lowest cabin temp that can be selected) wasn't helping...

    PP2000 tells me that switching AC on now brings evaporator thermistor temp down from 55C to 40.8C (with cabin fan spinning at lowest speed), at which point the compressor cuts out, and thermistor temp starts to rise again.

    Only weird thing - "Pressostat input" now shows "pressure INcorrect"!!!! Any explanation most gratefully received .



    PS - I had thought that only the aircon was playing up. However, additional functions of under-bonnet fuse #32 are listed as "Speed sensor, Reversing light, Diagnostic plug, Automatic gearbox" . The car is manual, so the last doesn't apply. Don't know about the "diagnostic plug" - the OBD plug seems to work correctly with or without this fuse - and no idea about "speed sensor" - there were no warning lights or any indication of problems apart from the aircon. However, just tested the reversing lights and sure enough, they don't work if Fuse #32 is removed!

    So if your 406 air con stops working, check your reversing lights before you do anything else .
    Last edited by Armidillo; 29th September 2016 at 02:21 PM.
    CXVingtCinq likes this.

  3. #3
    1000+ Posts BIGRR's Avatar
    Join Date
    Feb 2006
    North Rocks, Sydney


    My 605 air con stuffed around for about 18 months. Took it to a couple of "gurus" still no good.

    One day I removed the battery cover and had a look at how an auto electrician had fitted the about 18 month old new battery terminal!!! (Original round lead had been connected to a flat post!!)

    Connected it correctly and had no further problems.

    Free to check.
    Armidillo likes this.
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"

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