Electronics question - climate control components

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
User avatar
bobins
Donor 2023
Posts: 5697
Joined: 05 Jul 2012, 18:07
Location: Midhurst, West Sussex
My Cars: Kia Sportage
Mazda BT-50
Land Rover SIII SWB
V-F-R800
SL320
MX5
x 2871

Electronics question - climate control components

Post by bobins »

Brain picking time for all you electronics experts.... :-D

One of the climate control knobs in my X7 has started going intermittent - it's a common enough fault and will most likely affect all identical controls in the end. For the avoidance of doubt - it's this type of control :
Climate control
Climate control
It's the driver's side one that's playing up, so that would indicate it's a wear and tear related problem as the passenger's side still works fine and that gets a lot less use. I decided to take mine apart to see what's inside - hey presto....
Underside of knob - own work
Underside of knob - own work
This (above) shows the underside of the control knob, the red circles show a castellated metal ring which turns with the knob.
Sensor - own work
Sensor - own work
This (above) shows what I assume to be a Hall sensor, though it may well be a light sensor. The castellated ring passes through the sensor when you turn it.

Would it make sense that it is a Hall Effect sensor, or is it more likely to be a light sensor ? Is there any other type of sensor it could be ? Are Hall sensors known to go intermittent or are they either in a working state or fubar'd - same question for light sensors ? Could it be the ring that's at fault ? Is there anything that can be done to make them good again ? Re-magnetise the ring ? - or is that barking up the wrong tree ?
Any ideas ??????

Is it worth hoarding all the spare climate control panels now so I've got a supply to last me another 10 years ? :lol:
Last edited by bobins on 21 May 2018, 21:43, edited 1 time in total.
Sadly no longer a C5 owner :(
User avatar
xantia_v6
Forum Admin Team
Posts: 9053
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: Electronis question - climate control components

Post by xantia_v6 »

It is much more likely to be a light sensor, with quadrature detectors to sense the direction of rotation.

It is hard to see how such sensors (or even hall effect sensors) could suffer wear out, as they have no physical contact with a moving part.

Is there sideways pay in the control shaft?
User avatar
bobins
Donor 2023
Posts: 5697
Joined: 05 Jul 2012, 18:07
Location: Midhurst, West Sussex
My Cars: Kia Sportage
Mazda BT-50
Land Rover SIII SWB
V-F-R800
SL320
MX5
x 2871

Re: Electronics question - climate control components

Post by bobins »

Hadn't thought about play in the control shaft ! Difficult to quantify how much play though as there's a certain amount of slop on both control knobs, and it doesn't work however you hold the control :( The control is supposed to be bi-directional - and it's equally intermittent in both directions :? The previous time it went dodgy it wouldn't work from starting from cold from home, but would work once I restarted the engine after about 20 miles. This experience was repeated on the return journey. That could point to a voltage related issue... only the passenger side worked faultlessly :roll:
Sadly no longer a C5 owner :(
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37005
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5646

Re: Electronics question - climate control components

Post by GiveMeABreak »

In that second picture it looks like the metal is contacting that white contact strip at the top. Is it this that has anything to do with it and if so has it slackened slightly?
Please Don't PM Me For Technical Help

Marc
User avatar
xantia_v6
Forum Admin Team
Posts: 9053
Joined: 09 Nov 2005, 22:03
Location: France or NewZealand
Lexia Available: Yes
My Cars: -
1997 Citroen Xantia V6 (France)
1999 Citroen XM V6 ES9 (France)
2011 Peugeot 308 CC THP 155 (NZ)
1975 Jaguar XJ-S pre-HE (NZ)
x 825

Re: Electronics question - climate control components

Post by xantia_v6 »

If you have a working spare, you could try mating the mechanical half of one with the electronics half of the other, to localise the problem.
User avatar
bobins
Donor 2023
Posts: 5697
Joined: 05 Jul 2012, 18:07
Location: Midhurst, West Sussex
My Cars: Kia Sportage
Mazda BT-50
Land Rover SIII SWB
V-F-R800
SL320
MX5
x 2871

Re: Electronics question - climate control components

Post by bobins »

The contact strip at the top is a bit of sprung metal to act as a detent spring on the castellated section to give the control knob its 'notchy' feel as you turn it.

Good suggestion about swapping working bits (Xantia_V6) - I might invest in a second hand climate control section so I can do some testing.
Sadly no longer a C5 owner :(
User avatar
xf1ref
Posts: 206
Joined: 20 Feb 2012, 05:42
Location: Romania
My Cars: C5 2.0 HDI 163hp
x 10

Re: Electronics question - climate control components

Post by xf1ref »

In the third picture I think is the IR optical encoder. In the optical mouses are similar encoders at the scrolling wheel. Try first to see if there is a cold joint at the sensor or near pieces. If the control knob is ok I would suspect this sensor.
Post Reply