Yet another heater blower problem

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kosio
Posts: 13
Joined: 02 Jun 2004, 16:38
Location: Bulgaria
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Yet another heater blower problem

Post by kosio »

Hi all!
I know it sounds like it's been talked a lot about those problems but I think this particular problem was not discussed (at least I couldn't find it in the forum) :-(
Firstly, it's a 1994 (march, 1st version) 1.8i Xantia with aircon.
Problem is heater blower.
When engine off, speed to max I start the engine - sometimes fan blows on full speed, sometimes doesn't blow.
When I move the speed adjuster to anything different than max/off/auto (1,2,3 speeds) - it stops.
Then if I move it back to max or auto - it sometimes starts, sometimes not.
Whenever it "dies" like that, I "cure" it by turning off the engine than back on (with fan on max) - it starts almost always.
Tested it with aircon on and off - no difference.
Temp regulation lever works - hot on hot, cold on cold. Even the temp adjuster seems to work (climate) - after blowing on auto w/ aircon on and temp set to 22 - cuts out when temp reached (on auto) or blows hot for a while then cold again (on max) - maybe mixer motor not working?!
So here's what I did.
Dismantled the fan from under the glovebox (it's a LHD, BTW).
The fan has 5 wires going into it - 4 in a connector and 1 separate from the others.
Among those 4, there are 2 thik ones - ground and 12V (I read 12.6V at all times there, so I guess this rules out the contact switch...).
After engine start (speed on max) - fan works on max - I read ~8V on the outer thin wire - I guess it's the rightmost wire on component 8045 here http://citroeny.cz/servis/xantiaser/kli ... a80.5a.jpg) connecting to the climate ECU.
When I move the speed to 3 (2,1,off) I read 12.6V on same wire - fan stops. Move back to max - no difference - 12.6V - same as at off.
This leads me to the conclusion that the blower works, am I right?
I also dismantled the heat control unit (after removing the stereo - don't ask!) - I think it's the 8025 component on the above diagram.
Looks somewhat different in my car though - 2 variable resistors (working) - 1 controlled by the temp lever, the other preset(??) in 1 casing, connected to another casing with a resistor pack by 3 wires - all resistors measure about 1 (2? can't remember now) kOhms (exept one which reads 0 Ohms but is labeled '000') - those work too.
The whole control unit is connected to something (?) via 5 thin cables (as on the diagram). On 1 of them (an ending one I'm pretty sure) I measure differents Volts when speed controller set to different settings (2.8V, 3.2V, 3.8V, etc - numbers are by memory).
This makes me think climate controls work, right?
After studying the diagram I noticed that there is a "climate ecu" and a cabin temperature sensor (which looks pretty nasty on the diagram...) somewhere between the fan and the controls.
This cabin temp sensor I believe is located under the alarm diode on the dashboard above the stereo - the "button" w/ the holes in its cap.
What are the chances that this strange behaviour is caused by a malfuncioning cabin temp sensor?
Ah, BTW, the blower seems to have been changed in 1996 or later (it has 96 as manufacturing date - car is '94).
Also the temp sensor started making some buzzing noises just today when car powered up (contact). A hard tap on it makes it stop for a short while. When I opened things up yesterday I fiddled a bit with it trying to take it out ... unsuccessfully.
Also any tips on how to get the thing out will be appreciated. (I've ordered the Russek's manual but not here yet :-( )
Any comments are mostly welcome!
Cheers,
kosio
BTW, where is the "climate ECU" - 8080 component on the diagram - located?
jozivic
Posts: 9
Joined: 27 Oct 2003, 19:18
Location: Slovenia
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Post by jozivic »

What are with thyristors on the fan motor, did you observe it. It is quite common problem with brushes in motor also, I have to change it every 80000km. It is hard to find it while there are special hardness material (mix charcoal and copper). If the motor is from 1996, you freely change the brushes, then try to fix other problems. Last time when I try to fix problems with fan I have to change spare fan block in complete, fortunately I found one in scrap-place in Venice (Italy), where old Xantias in good condition are common guests. Excuse me for bad English.
kosio
Posts: 13
Joined: 02 Jun 2004, 16:38
Location: Bulgaria
My Cars:

Post by kosio »

Studied the diagram a bit more (http://citroeny.cz/servis/xantiaser/kli ... a80.5a.jpg). Seems to me that user input is taken from climatic controls on the dash, then "filtered" through the cabin termp sensor before taken to the Clima ECU.
Does that make sence?
--kosio
kosio
Posts: 13
Joined: 02 Jun 2004, 16:38
Location: Bulgaria
My Cars:

Post by kosio »

Hi jozivic,
Thanks for the reply.
Unfortunately I can't get access to the pair of transistors on the fan casing (how to disassemble the fan anyone?). But the fan cuts in/out like it's supposed to, so they should be ok (?).
About the brushes - same thing - cuts in nicely, doesn't seem to have a problem there.
--kosio
Brian Oblivion
Posts: 98
Joined: 19 Jan 2004, 14:48
Location: United Kingdom
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Post by Brian Oblivion »

I wonder if you have two problems: I used to have the same blower speed selection problem i.e. it only worked on a couple of settings. It also used to cut out at baffling intervals refusing to re-start until it went round certain corners, over bumps etc
I never solved the blower speed selection problems but I found the intermittent fault to be a poor electrical connection block in the loom under the steering wheel that was "tired"/corroded and caused a large resistance, so much that the wires felt like hot liqourice bootlaces and the block was too hot to touch. I made a new block up and solved the intermittent on/off operation of the blower.
That was on a 1994 Pug 306 1.9 XLD BTW
kosio
Posts: 13
Joined: 02 Jun 2004, 16:38
Location: Bulgaria
My Cars:

Post by kosio »

Hi Brian,
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I wonder if you have two problems: I used to have the same blower speed selection problem i.e. it only worked on a couple of settings.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Yes, that's what I recon too - 2 independent problems. I'm planning to take out the battery and clean the ground contacts under it as some of the members here have suggested and see how this works out.
Re your speed sel problem, on what settings did it work and on what it didn't?
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">It also used to cut out at baffling intervals refusing to re-start until it went round certain corners, over bumps etc <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Hmm, haven't noticed such a behaviour...
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I never solved the blower speed selection problems but I found the intermittent fault to be a poor electrical connection block in the loom under the steering wheel that was "tired"/corroded and caused a large resistance, so much that the wires felt like hot liqourice bootlaces and the block was too hot to touch. I made a new block up and solved the intermittent on/off operation of the blower.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Does the Pug have the same wiring under the wheel? I understand you're talking about the wires coming out of the ignition switch then?
Thanks for your input but it seems I'm going a bit over my head with this so I best take it to a garage... :-(
Cheers,
kosio
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