406 Heater Blower Fan

Discussion in 'Peugeot 406' started by MostWanted, Sep 21, 2005.

  1. MostWanted

    MostWanted Guest


    I am really getting frustrated with this now.
    My heater blower fan of my 1998 406 ONLY works on full power.
    I was told I needed a new blower fan, so I replaced it.
    Still no joy.
    So I replaced it again.
    Same problem.

    Then I was told it would be the digital control unit (with all the
    buttons on it). Put in a new (expensive) one of those together with
    another new fan.
    Same problem.

    What could the problem possibly be?

    It works, but only on full power and its really annoying because things
    like a/c you would rather have working on low-medium fan which I cannot


    MostWanted, Sep 21, 2005
    Hon Segun Abioye likes this.
  2. MostWanted

    Nom Guest

    Is there a resistor pack to offer differing voltage levels to the fan, based
    on what the "digital control unit" tells it to do (ie, "digital control
    unit" simply replaces the physical switch, and the speed is still adjusted
    by resistors as in a "normal" car) ?
    Nom, Sep 21, 2005
    Hon Segun Abioye likes this.
  3. MostWanted

    MostWanted Guest

    the resistor pack is built onto the fan unit no?
    So everytime I changed the fan unit, effectively I was changin the
    resistor pack aswell right?
    MostWanted, Sep 22, 2005
  4. MostWanted

    G.T Guest

    I don't know for AC-equiped cars, but often an external pack, due to
    dissipation imperatives. Often made of 3 resistors (the 4th speed being
    direct) and a thermofuse / thermodiode acting like a fuse.

    I've got a part called "module" next to blower fan for AC-equiped Mk1 406s
    (codename D8). I don't know if it's the resistor pack.

    BTW, I'd like to drop a line about this : don't you, guys, think it's
    incredible to see resistor packs fit nowadays ? Bad efficience (useful
    power/used power ratio) for a speed variation, they'd better fit a DC/DC
    converter, which isn't more expensive, if you see the price for a set of
    power resistors.

    205 Diesel & turbo-Diesel : www.205d.com
    G.T, Sep 22, 2005
  5. MostWanted

    Nom Guest

    I don't actually know - I was just trying to establish how the system works,
    so we could work out what was bust :)

    This is the sort of thing an auto-electrician should have no trouble with -
    I'd be looking in my Yellow Pages.
    Nom, Sep 23, 2005
  6. MostWanted

    Nom Guest

    I think it probably is. You should soon be able to find out, with a bit of
    wire-tracing and multimeter work.
    No idea - I'm no electrician :)

    Car makers always use "If it aint broke, don't fix it". Resistor packs may
    well be crap - but if they're cheap and reliable, then there's no point in
    Peugeot spending £££ on researching and developing a replacement.
    Nom, Sep 23, 2005
  7. I don't know if this is the case with the fan i the 406 but it is the case
    on 605's and 205's at least.

    The fan i equiped with a electronic regulator, with a bypass relay.
    The bypass relay is operating only at full speed, otherwise the electronic
    regulator is powering the fan. The electronic regulator is probably faulty.
    This could explain the symptoms you are describing.

    The engineer that developed the regulator did not have sufficient electronic
    skills to understand that placing two bipolar transistors in paralell
    without some kind of arangment for current sharing, can be a recipe for

    The transistors in the fan are probably blown, (both of them).

    If you, or any of your friends have the necessary skills, you can find
    replacements, and repair the regulator yourselves. Just replace both the
    TO-3 transistors. Otherwise, you will have to try to get hold of a working
    fan, or a working regulator.

    Hendrik Skarpeid, Sep 23, 2005
  8. MostWanted

    G.T Guest

    That's my idea too, but removing parts to have an access could well be a
    pain. Glad I don't have to do it myself !
    You don't know what you're missing ;-)
    I do agree with you, but trust me, such an electronic module takes about 2
    hours to design (and it's a max value) and costs about £5 to build (and
    that's a large amount, too).
    Just for fun, I've just designed such a PCB. My crappy design (took me 10
    minutes) fits on a PCB which is only 48*25mm (18.9*9.84mil) - I could do
    even better if I wanted to.

    205 Diesel & turbo-Diesel : www.205d.com
    G.T, Sep 23, 2005
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