405 issues heating A/C fan
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  1. #1
    Fellow Frogger!
    Join Date
    Oct 2004

    Default 405 issues heating A/C fan

    It's bloody hot in Melbourne at the moment and there is no sign of abatement.
    To the point.

    Internal fan not working.
    But remove it and solid wire 12volts and voila! It goes-flat out.

    Now I know what you're thinking! It not the $180 electronic controller because on professional advice I bought and fitted a new one.

    On checking the 4 pin connector this is what I am getting
    1 orange = 0 volts
    2 black = earth
    3 brown = 0 volts
    4 red = 12 volts

    On pin 1 & 3 as I slide the fan spees control across it full range (ignition ON)
    ther is no voltage change as I would have expected.

    I suspect a fuse, but as I don't have a handbook/manual does anyone know the position of the fuse and its value?


    A friend who should know about these things suggested a power transistor that may have gone to lunch. But where is it on a 405 and is there an easy test?

    How likely could it be an issue with the slider control (series 2 405) ?

    Any other thoughts?


    Predicted temp tomorrow 40 degrees in the shade!
    Last edited by David M; 25th January 2006 at 07:57 PM.

  2. #2
    Fellow Frogger! Clogzz's Avatar
    Join Date
    Mar 2005
    Sydney 2087


    Don't understand what's going on here.
    Is it hard-wired and going flat-out, or does it not go at all ?
    The orange and pink (?) wires will only have low voltages on them when the engine is running.
    Don't know the voltages or fuses, but can look up.
    It's not likely that the fault would be in the slider control area.
    The speed control transistors are on the underside of the motor.
    They go short and cause the motor to be flat out all the time.
    If they are short, they measure short between the outer case and one of the 2 pins, don't know which without seeing.
    All this is for the Xantia, and I hope that the 405 is the same.
    Despite having 12 Volts on the red wire, I would still suspect the ignition switch to cause the fault, a very common stunt on the Xantia.

    Story here:

    Intermittent or erratic interior fan on Xantia

    And have a nice, summery day in Melbourne tomorrow.

    And how come the emoticon finished up at the top ?
    2003 C5 2.0i AL4 205,000 km 76372389

  3. #3
    Fellow Frogger! Meggsy's Avatar
    Join Date
    Aug 2004


    The early 405 fans sufferd from water from the A/C units and there is a relay below the power transistors that fails.. you can clean the relay contacts some times and it works other times you have to mbypass the relay

    Hope this helps
    Current - 4007HDi
    Had - 407 HDI 406 SV 404, 504, 505 GR and STI. 405 GR ( carbie version) STI, MI16
    And an Austin 1800
    Learnt to drive in 203 Convertible and a 403 SW

  4. #4
    Join Date
    Apr 2004


    I had a similar problem with mine when it was 40*C in Sydney recently.
    I replaced the PLUG on the RED wire that connects to the fan motor.
    I cleaned and twisted the male part slightly to enable the fitting of a larger plug( didn't have the correct size). Instant cure, and hasn't faulted since.
    Easy job with satisfying results.

  5. #5
    Fellow Frogger!
    Join Date
    Jul 2004

    Default .

    I think its fuse number 18 and its 25 amp. I know this because mine just blew, about to try and fix it! It will tell you in the handbook what number fuse controls what.
    1984 505 STI

  6. #6
    Fellow Frogger!
    Join Date
    Oct 2004

    Default 405 heater fan

    Thanks for the feedback so far. I will go hunting the fuse and I'll try your location, luchcutter. Could you please check as I DO NOT have a handbook! That is the frustrating part of the fault.

    My fuse #18 is 10amp and appears OK!
    Last edited by David M; 28th January 2006 at 03:41 PM.

  7. #7
    Fellow Frogger! Decca's Avatar
    Join Date
    Jul 2004


    The power transistor is in the fan motor housing.

    Sounds like the fan itself is ok as you can run it direct off 12v

    On the 4 pin connector... Pins 1 and 3 go to the sliding fan speed control, There is no voltage here, only resistance which will vary as you operate the fan speed control. so unplug and check with an ohm meter This resistance alters the bias on the transistor which controlls power to the fan. If the resistance varies and the plug in connected properly... sounds like the transistor has gone open circuit ( if the fan doesnt work) or shorted ( if the fan runs flat out).

    Any warranty on the controller/transistor if it has to be replaced??

    Present --2016 2008 Outdoor / 2014 RAV4 Diesel (My utilitarian beast)

    Past -- 19?? 403 / 1974 504GL / 1972 R12TL / 1995 405SRi / 1997 406ST / 1998 306XT / 2004 406HD1 / 2008 308XSE HDi / 2008 307XSE

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