Taking this and Adrian's response together, would it be safe to assume that
if the rear-screen demist is still OK, the semiconductor bank in the heater
is the more likely fault, and is there a difference between A/C and non A/C
cars - because the same has happened to mine...except that when I pull off
the separate thin pink wire to the heater, I can get the blower to run at
one speed (moderate) if I start the car with the blower control "off", or
full blast if I start the car with the blower control set to Full! Mine has
A/C, but I believe there are differences in the blowers between A/c and
My rear defogger doesn't work AND my fan fails to respond to manual speed
setting (except FULL) but I had never conencted the two .
what is this "starter-lock" of which you speak?
intrigued of Shoreham
and I became inspired,
That's where you put your key in to start the car. (I'm Dutch so
forgive me if I can't find the correct words sometimes)
There is an electric circuit in there that can short circuit sometimes
(happened to me). That causes the fan and the rear defogger to fail.
But when that happens they are both completely dead so that doesn't
apply to your car.
d:J0han; Certifiable me
2Rowdy means the ignition switch - it's a common fault caused by the
switch actually having to switch the high current involved with the rear
window demister and the blower fan.
The electrical part of the switch can be replaced without resorting to
new key lock but Citroen will only sell them together. There is a simple
modification that you can make to put a relay in the circuit so that thw
switch only has to handle the coil current for the relay. If you let me
have a real email address I can send you a pdf with the circuit diagram
for this modification. Maplin (in the UK) sell a suitable relay (12V,
40A, SPST) for a couple of quid and it takes about 15 mins to fit.
I have the same problem on my xantia with the heater+rear defogger
(well my fan heater do not work at all). Pls can u give me instructions
on how install that relay on the ignition switch.
The ignition switch is too weak to handle the current needed by the blower.
The cure is to use a relay (any relay for road light will do):
At ignition switch, unplug the connector (2 big wires) going to the blower
Plug them to the relay and command the relay via a +BAT after contact ( i added
a wire coming from the radio).
My car: xantia 1.8L 16V 1996
La vitesse vous effraie ? Windows est fait pour vous.
Why not just remember to switch the blower off (as you should) before
turning the key?!
contact ( i added
It would also be advisable to either use a relay with built in fuse
or ad a line fuse into the load feed - an electrical fire in a car is
not nice, especially if one is at high speed when thick acrid fumes
start billowing out from the dashboard...
it's got AC ...
does that mean the two ARE connected ? the fan speed thing is just plain
annoying as it's quite loud at full chat, but with winter approaching I am
missing my rear demister already!
Cars with A/c have a control module that is different to the relatively
simple multi-resistor switching on non-a/c ones.
On mine, the rear demister works fine, apparently exonerating the ignition
switch as the culprit, but the fan works on full chat or low.
Here's the rub - to begin, the fan started running all the time, on a kind
of fast-but-not-full-blast setting. I took the fan itself apart, but had no
way of testing the semiconductor speed regulator that is built into it, and
still don't know if this could be the culprit.
Anyway, it appears that two of the wires from the motor go to the a/c
control module, not directly to the dash switch, so the fault could lie
there - although on mine the a/c itself seems to work fine. Bizarrely,
there is a pink wire to the heater which, if disconnected, allows the fan to
run at either max or auto - but max will only work if it is selected before
I start the engine!
Short of replacing every module progressively I do not know how to deal with
it - I just wish I knew how to test the semiconductor block in the fan
assembly, as I am still suspicious that it could be to blame, and would
probably cost a couple of quid from the breakers - but how would I know if I
had a good one.......?
And they called Joe Lucas the Prince of Darkness.....!
TF - thanks for the feedback ... sounds like I have a variation of a subset
or superset of your problems!
On mine the fan wont run unless the engine is running which I find very odd
Luckily the fan speed thing is only a minor gripe - the rear defoggger is a
more annoying malfunction.
Dunno, my Xantia fan used to act weird if the heat was on full though, on
Auto it'd switch the fan off if I selected full heat, and on manual fan
speed it was always hotter if I moved the heat to the "28" position instead
of full hot.
Doubt this helps, but hey, this is usenet.
Pete M - Using the Scouse Side of the Force -
Range Rover Vogue EFI
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.