Auto - Manual failure

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ng4xjs
Posts: 296
Joined: Thu Jul 29, 2010 12:49 pm

Auto - Manual failure

Postby ng4xjs » Sat Sep 30, 2017 9:19 pm

Any thoughts greatly welcomed. Coming back from Yorkshire last week, air-con set to cold I was getting warm air to the footwell and not very much from the face vents. Switching to manual and all works normally, ie cold air where it is wanted. Seems therefore that all the physical controls are functioning normally. I don't think it needs gas as did this last year but any other thoughts ideas greatly appreciated.

A complete aside I switched to using the 97 octane petrol in total at the beginning of the year (as opposed to occasionally). Car seems to run better with improved fuel consumption and recent MOT suggests much lower emissions.

Nick

ptjs1
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Location: Kent

Re: Auto - Manual failure

Postby ptjs1 » Tue Oct 03, 2017 3:29 pm

Nick,

As the system seems to work when in Manual mode, that seems to mean that the system will blow cold when "told to". So the only difference is that in Auto mode, it detects the cabin temp via the sensor. and sets the aircon temp to adjust accordingly. So it could be that the cabin temp sensor is failing / blocked / just not detecting properly. I think that's the sensor that is located on the behind of the kick panel on the passenger side under the airbag. The panel drops down easily and there's a small sensor screwed to the panel. I THINK that's the one.

Of course, as so often, I could be completely wrong, but it sounds plausible, doesn't it?

Cheers

Paul
1995 XJS 4.0 Convertible
1980 XJ-S Pre-HE
Jaguar 4.2 Supercharged engine (but not with a Jaguar body..)

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ng4xjs
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Re: Auto - Manual failure

Postby ng4xjs » Tue Oct 03, 2017 7:01 pm

Thanks for that Paul - When you think about it makes absolute sense, I'll have a look. Coincidentally working perfectly at the moment, even down to hearing the centre vent flaps slamming open.

I'll check the sensor at the weekend.
Nick

davidr
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Re: Auto - Manual failure

Postby davidr » Tue Oct 03, 2017 7:33 pm

As cabin air is drawn past the sensor the usual issue is that it becomes a fluff trap so either gets blocked or the fluff insulates the sensor so it's unable to detect temperature changes. A good start would be to clean the sensor.
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1996 XJS Celebration Conv. (shown on the JEC stand at NEC Nov 2015)
2001 XKR Convertible

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1989 XJ-S V12 Coupe. 2006 XJ TDVi Sovereign. 1995 XJ6 3.2. 2013 XF 2.2d. 2009 X Type 2.0d Sovereign estate

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ng4xjs
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Re: Auto - Manual failure

Postby ng4xjs » Thu Oct 05, 2017 9:15 pm

Good point - Thank you David.

Nick


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