C5 X7 True 'Climate Control' ?

Post your Cit/Peu/Ren air conditioning queries or advice.

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EDC5
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C5 X7 True 'Climate Control' ?

Post by EDC5 » 24 Sep 2017, 11:38

Just a quick question: Whilst browsing the menus of Diagbox under the climate control live parameters there only appears to be temperature sensors in the ducts supplying air to the passenger compartment. I don't believe the C5 has actual temperature sensors in the passenger cabin like other cars with CC do.

I really like how the fan speed is influenced by the sunshine sensor, that is a very clever feature; however, without a temperature sensor in the passenger compartment the car is assuming that the cabin will cool (or heat) to the temp of the air being supplied... which is not always true.

Do the highest spec Citroens have additional temperature sensors throughout the cabin out of interest?

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Re: C5 X7 True 'Climate Control' ?

Post by GiveMeABreak » 24 Sep 2017, 12:41

The X7 (on our models) does have an Air Temperature Probe Elis - one for each side on Bi-Zone System.
X7 Air Temp Probe.PNG
1) Evaporator Sensor
3) Sunlight Sensor
4) Air Temperature Probe

There are only 2 systems - Mono or Bi-Zone.
The Air Quality sensor monitors contaminants and shuts of outside air when reversing or when in traffic and exhaust fumes are detected for example, and also when screen washers are activated.

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Re: C5 X7 True 'Climate Control' ?

Post by EDC5 » 24 Sep 2017, 13:11

I see, are the air temperature probes located in the cabin or in the stream of air to be blown out of the vents? It's the latter then I'm not sure how it can be a true climate control system.

Blowing 20 degree air for example into a cabin won't cool it to 20 degrees due to the heat leaking in from elsewhere. Thats why some cars have a sensor in the cabin away from the draught of the vents to decide what temperature air needs to be blown in.

Does the C6 use the same sensor system for its CC?

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Re: C5 X7 True 'Climate Control' ?

Post by GiveMeABreak » 24 Sep 2017, 13:17

The C6 has exactly the same as the diagram above Elis.

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Re: C5 X7 True 'Climate Control' ?

Post by GiveMeABreak » 24 Sep 2017, 13:38

This is just what it says about the system - note the last point:
General Operation
The automatic air conditioning system permits automatic regulation of the operating temperature required by the user :
  • Automatic air conditioning with air diffuser
  • A low diffusion rail at the front permits an even distribution of air in the lower part of the vehicle
  • Air outlets in row 2 with optimised location on the centre pillar
  • A pollen and odour filter
  • Automatic recirculation of air when reverse gear is engaged and when the screen wash is used, to prevent unpleasant odours from entering the vehicle
  • Pollution detector which automatically isolates the passenger compartment from the outside air
  • The automatic regulation system is connected to the sunshine sensor.

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Re: C5 X7 True 'Climate Control' ?

Post by EDC5 » 24 Sep 2017, 13:43

Understood. The air outlets in row 2 are a very welcome feature in cars I feel! and the air diffuser is a nice touch.

I see, they're using the sunshine sensor to estimate the cooling requirement of the cabin, very clever. However I think a cabin mounted temperature sensor, perhaps in row 2 would help give the ECU a bit more solid data to go off when deciding the cooling/heating requirement.

It's just in most cars with climate control I always leave it set to about 21 but in my C5 I have to move it up/down depending on the outside temperature.

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Re: C5 X7 True 'Climate Control' ?

Post by xantia_v6 » 24 Sep 2017, 13:44

It can't only be using the sunshine detector, as that is not very effective at night, and night time ambient temperatures vary from -30 to +30 degrees.

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Re: C5 X7 True 'Climate Control' ?

Post by GiveMeABreak » 24 Sep 2017, 13:49

Mike - that sunshine sensor is actually a heat detector I believe.

@ Ellis: Yes, the digits on the Climate Console are just degrees of operation - not degrees of temperature, so I guess once set it will just maintain the equivalent temperature and adjust according to outside temp / sunlight / heat sensor (on the dash) and other factors.

If you've ever been driving along in bright sunlight, then hit a tree covered area of the road that obliterates the sunlight - you can usually hear the system compensate the air flow and direction as a result. The sunlight / heat sensor must be quite sensitive to changes.

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Re: C5 X7 True 'Climate Control' ?

Post by EDC5 » 24 Sep 2017, 13:59

GiveMeABreak wrote:
24 Sep 2017, 13:49


the digits on the Climate Console are just degrees of operation - not degrees of temperature,

If you've ever been driving along in bright sunlight, then hit a tree covered area of the road that obliterates the sunlight - you can usually hear the system compensate the air flow and direction as a result. The sunlight / heat sensor must be quite sensitive to changes.



Yes I read that in the manual... Personally I think it's a bit misleading that they choose their 'degrees of operation' to be on the same scale as reasonable cabin temps in degrees Celsius instead of say....0 to 5 haha :lol: .... very sneaky.

Yeah, as I say the brightness sensor feature is really good, I have played with it by covering it with my hand and hearing it adjust. All I'm saying is that it should use some other means of detecting the temperature of the cabin as there is no guarantee that the cabin will heat/cool to the temperature of the blown air.. there must be an offset either higher or lower than the set temp to account for 'leakage'.

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Re: C5 X7 True 'Climate Control' ?

Post by GiveMeABreak » 24 Sep 2017, 14:11

I've just had another look at the diagrams and 8024 and 8028 are the left and right passenger compartment air thermistors, so that would indicate they are able to monitor the left and right 'compartment' temperatures.
X7 Thermistors.PNG
X7 Thermistors.PNG (9.29 KiB) Viewed 1240 times

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Re: C5 X7 True 'Climate Control' ?

Post by EDC5 » 24 Sep 2017, 19:18

Ok, that makes sense, seems I was overthinking it a bit.