Xantia Blower Problem but Not the Ignition Switch One

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xantom
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Xantia Blower Problem but Not the Ignition Switch One

Post by xantom »

I have a 1998 R reg Mk 2 Xantia 1.9 TD SX Estate. I have always loved the styling and technology of Citroens and once owned a CX Pallas petrol version for a year before the realities of income versus expenditure forced me to get rid of it. The memory has never faded and I always knew I’d get another Citroen. I am basically delighted with my Xantia and enjoy maintaining my own vehicles so it’s pretty much my perfect car. I have happily and successfully changed a left driveshaft, accumulator and anti-sink spheres and all the routine filters etc but of course, there’s always that one thing I can’t seem to sort out. I’m an avid reader of the forum and use you guys as an extra brain and library, and I’m hoping the corporate brain might have something to help here.
My blower doesn’t work properly. I have AC in my model. Because of the model, I shouldn’t have the ignition switch problem the earlier cars suffer from, and I haven’t actually checked the switch because I don’t have the associated rear windscreen symptom. I bought the car with the problem and was typically overoptimistic about what I could achieve. Before I bought it the owner had ‘his mechanic’ bodge it during its last service. The bodge consisted of a switched wire from the blower motor to earth so when selected it ran full blast. OK as a temporary frig but he used too thin a wire and the wire and the switch heated dangerously, so I removed them. If the engine is started with fan slider in the MAX position, it will, after 2-4 quick engine start/stops come on full blast and stay there. I’ve survived winter with the stop/start to MAX blast process for de-misting but summer’s not far away and I’d really like the air conditioning and a fan that doesn’t have to sound like a jet taxiing past.
The Symptoms I Do Have
The fan always runs at a minimum speed with occasional minor momentary increases. These little momentary increases happen when the car is stationary so I’m pretty sure they can’t be due to air being forced past the fan.
If the engine is started with fan slider in the MAX position, it will, after 2-4 quick engine start/stops come on full blast and stay there. However, moving it to any other setting then reverts it to minimum blow and it will not go back to full on.
If I set it to one below MAX and do the start/stops it will come on at that setting but only for a second or so before then reverting to minimum again. No other setting does this.
Even in the stop position (the little fan symbol on the slider) it still runs at minimum.
If I disconnect the ECU and put the slider to MAX it will start every time in MAX but then the other symptoms above remain.
The air cooling function of the AC works very well but has no effect (apparent) on the fan.
What I’ve Tried So Far
I thought it might be the transistors problem that Citrojim posts about and he actually tested out my blower control circuit board and it passed as fully functional. Can’t thank him enough for his generosity is doing that.
I’ve tested and also swapped over the green circuit breaker above the accelerator pedal: no change.
I’ve been to a scrappy and tried a different slider control unit: no change.
I’ve also tried a different ECU at a scrappy: no change.
Now I realise those could just coincidentally be 2 duff bits from a scrappy so I’m currently trying to locate someone with a working system to let me try their ECU.
My Conclusions
That’s poor paragraph heading because I don’t have any actual conclusions. Some aspect of variable control seems to be working because the fan does seem to be trying to respond but seems to be getting stifled before it can lock into its correct power setting. I am stumped and grateful for any thoughts and advice on this.
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CitroJim
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Post by CitroJim »

Hi Tom,

I reckon you've gone through virtually all of the obvious and that really only leaves the temperature sensors that tell the ECU what is going on. One or more of those could well be the problem.

There are a fair few sensors dotted around the heater box and generally, if one or more reckon the temperature is what it should be then the fan will indeed run at the slowest speed.

There are five main temperature sensors: The cabin sensor behind the little grille on the dash and this has a tiny fan ehind it to draw air across it. The there is a sensor for outside air temperature located just downwind of the recirculation flap near the air inlet on the bulkhead, one for the foot-level vents, one for the face-level vents and one on the A/C evaporator.

The big problem is that none of them are easy to get to and involve a dash removal.

The very simplest way to check their operation is to run a Lexia diagnostic tester across the A/C ECU. Not only will it read any stored faults but it can do a full test of the whole system and give live readings of what the various sensors are doing. It'll also test the fan speed control and A/C function.

To get to the bottom of this, a Lexia session will be invaluable.
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
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Clogzz
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Post by Clogzz »

The sliders all pack up in the same way, with the wiper going askew first, then falling out, as mine did:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=23767
2002 C5 2.0i AL4 230,000 km 76372389
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falling-out-with-my-car
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Post by falling-out-with-my-car »

I know its a long time ago but why didnt anyone consider that the blower motor brushes may be very worn down esspecially as it had been running flat out for quite a while, I had all these symptoms took the blower motor to a company that recons automotive motors alternators etc and bought some new brushes for 50p the blower works beautifully now it used to run very slow with occasional bursts of high speed, the brushes are difficult to change but it is possiable and fiddly.
regards nigel
Citroen Xantia S2 1.9 TD estate 189K soon to be broken for parts Jan 2017 headlamps & radiator fan assembly already spoken for & A 1987 Citroen 2CV6 special just for fun.
New addition Citroen C5 2.0 HDi Exclusive Hatch purchased 09/12/2016 with 83K on the clock.
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