'99 Xantia S2 Max Blower Speed drop off

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Edhertz
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'99 Xantia S2 Max Blower Speed drop off

Post by Edhertz »

I’m writing to ask if anyone has been where I am now with the blower speed control. Briefly
summarising what is happening; with the engine running, I move the slider to the max position and the fan will not run. However after a delay of approx 1 min the blower comes on for approx 2 secs and then stops. This cycle is repeated if I leave the slider in the max position. If I move the slider to the auto position, there is a delay of approx 1 min after which the blower starts and stays on. I can then move the slider to the off position and the blower stops. Further movement of the slider to the max position increases the blower speed until at max speed the blower cuts out. With a bit of careful handling I can avoid the ‘drop off’point so the blower remains on. Any ideas,
Cheers in advance

admiral51
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by admiral51 »

As yours is a S2 then i would tend to ignore some if not most of anything about the S1 ignition issue in Super Sticky but there is some good info on location of the relay that was introduced for S2 Xantia to cure the S1 issue.

Bear in mind that the post referred to was maybe 14 years ago and you like me have a S2 Xantia that is 20 years old so it could be the motor getting to the end of its life .
When was the cabin/pollen filter last changed trying to push air through a brick wall tends to overheat the motor and can/could stop it running at full speed or maybe a combination of both ?
Notice you say it works on auto and then off if slider is switched to off and then will work on manual settings to close to max then stop.
Happy to be shot down in flames as usual lol but it does take a little time for auto to detect cabin temp and set fan speed accordingly.
What does it do if using auto if cabin temp is cool and slider set to cold, does fan speed increase if slider set to hot and vice versa ?
My first point of inspection would be the cabin/pollen filter, i have run the blower without it in for testing to see how good/bad the blower is but i know it is there for a reason :)
Have you checked the air intake is not blocked, no air no blow :)
Colin

Edhertz
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by Edhertz »

Thanks for reply. Pollen filter's fine and can confirm the fan speed behaves in the manner you describe in the auto position. Bench test shows current draw at approx 20A which I understand to to be normal so would like to assume fan motor is o.k. ....... maybe. Will check current draw in the car tomorrow,
Cheers

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white exec
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by white exec »

That figure of 20A for full speed is about right. Speed is controlled by a pair of darlington transistors on the motor control board, controlling the voltage supplied to the motor. These work well enough for speeds up to the last step from maximum, at which point the current pulled by the motor almost doubles as maximum is selected. This current is on the cusp of the specs of the transistors, and so a relay was included on the board which cuts in at max speed, bypassing the transistors, and delivering full battery voltage to the motor.

If the relay should fail to operate properly, the transistors are left to cope with the full load, and the circuit may shut down as a result.

The original and genuine Valeo control boards contain good-quality transistors of the correct type, although with a not over-generous spec. There are a large number of Chinese copies of the board offered for sale, some of which actually contain the wrong type of transistor, and the life of these boards is limited.

It's also a good idea not to leave the blower on max speed when leaving the car. Start-up current for the motor at full speed can be substantially higher than even that 20A.

Edhertz
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by Edhertz »

Thanks for replies. Comment regarding the load overload relay sounds interesting. I checked the blower motor current / slider position relationship from ‘off’ position to ‘max’. Started at 4.5A and did not change until approx 2/3 way across when it increases to approx 17A. At ‘max’ increases momentarily to 20A then crashes. I am assuming there should be a linear change so guess the control pot could be acting up. There are climate control topics on the forum but couldn’t find similar to this. This all follows on from a F 21 contact 'black death' melt down nightmare ending in a bypass,
Alan

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white exec
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by white exec »

Not sure about the slider-pot control, but the fully automatic (electronic climate control) panels do not control the motor linearly - the motor speed climbs rapidly in the last few steps towards Max speed.

Edhertz
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by Edhertz »

Thanks again for reply. Just had an M.O.T fail on o.s lower suspension arm bushes and ball joint so must move on from this one for the time being. I will put a temporary stop on the slider fascia so I am at least getting some sort of blower action without it crashing. I've also found a split in one of the rear strut gaiters just to round things off!
Alan

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Re: '99 Xantia S2 Max Blower Speed drop off

Post by Hell Razor5543 »

Ouch to all that lot. When I had a problem with the bushes on my last Xantia it was easier (time wise) to buy and replace the whole wishbone than to buy and fit replacement bushes (as, if they are not correctly lined up when fitted they don't last very long). If you decide to replace the wishbone do NOT tighten up the securing bolts past finger tight until you have the car bearing her weight on all four wheels and at normal ride height. That way the bushes will end up in their default position, and should last a long time. If you tighten them up to the correct torque with the wheel still in the air the bushes will be out of position, will twist when the car is back on her wheels and level, and the bushes won't last very long.

Edhertz
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Re: '99 Xantia S2 Max Blower Speed drop off

Post by Edhertz »

Thanks for comments. Replaced 2 x Bushes, 1 x ball joint, 1 x ball joint heat shield. Total cost approx £31.00. M.O.T pass and it's all go for another year. Back to blower problem, then rear strut gaiter,
Alan