Citroen C5 X7. Interior temperature hotter than the surface of the sun according to readings.

[JimiEZ]

I'm driving a C5 X7 -13 HDi 2.2 tourer with bi-zone auto AC. LHD, which I've owned about a 1½ years. Last summer AC cooling worked fine, but this summer I noticed that the AC was doing basically nothing. I was on a longer trip when I noticed the lack of cooling, but figured it was just low on juice, so I just rolled in to a random shop along the way and asked for a refill. They did as asked, but reported it won't help since my compressor is shot.

This was less than stellar news, but still something that can be fixed pretty easily with money, so once I got back home, I took the car to my regular shop for AC maintenance and possible compressor replacement. They did their thing and reported back to me that the compressor was fine and running normally when forced to do through software, and that mechanically all parts of the AC system were fine. However, they also told me that the passenger side interior temperature sensor was reading 5600 something Celsius, which was obviously a bit excessive, as hot as the car was during the worst of the heat.

At this point, they confessed that they have no idea what's wrong with the AC, but suspected it had something to do with this sensor. They were also pretty up-front about the fact that they *could* spend a lot of time poring over the issue, but it would probably be pretty expensive and I should probably look into it myself first. Note that they not a Citroen shop or anything like that, even though they have a reputation of being pretty good with PSA cars.

All of which leads me here. While googling the issue, I found a thread here (viewtopic.php?t=65864) with a similar sounding issue, though it was about the previous model. Figured it was worth the shot checking out if the sensor was located in the same place in the my later model too, but I've had no luck finding it. Which is a bit annoying, given that removing the glove box was a huge pain in the ass. Furthermore, reading some more threads here, I came across some posts suggesting that cabin temperature isn't actually measured at all!

Any suggestions on how to proceed? Unfortunately I don't have access to diagnostic equipment at home.

[mickthemaverick]

Hi Jimi and welcome to the forum
I have only had MK1 C5s so I'm afraid I can't offer much advice here other than to suggest you may need to check the external temperature sensor as well as the internal as I believe the ECU uses the difference betwwen the two to determine its actions. I'm sure someone with proper knowledge of your model will pop up soon and offer their wisdom. In the meantime have a general look around the forum from the board index above as you will find many non car related topics under discussion and you are bound to find something to interest, amuse, intrigue or even educate you!!

[GiveMeABreak]

The only sensors on the system are a Blown Air Temperature Sensor on the left and right side of the unit and an Evaporator Temperature Sensor, along with an Air Quality Sensor.

So I suspect that you may have a faulty blow air sensor on one of the sides confirmed by your garage.

The blown air temperature sensor measures the temperature of the flow of air passing around the sensor from - 40 °C to + 100 °C.
The evaporator temperature sensor measures the temperature as close as possible to the evaporator.

After a stationary period, and after receiving the outside temperature, sunshine and blown air sensors information, a calculation estimates the passenger compartment temperature.

This is the Blown Air Temperature Sensor:

This is the Blown Air Temperature Sensor (right):

This is the Blown Air Temperature Sensor (left):

Now I'm not saying this is the cause, but if your A/C specialist has diagnosed the temperature as being off the scale of one of these, then is stands to reason that this may be the cause of the system shutting off the A/C. Of course it could be the evaporator sensor, that again may be switching off the A/C if it thinks the system is too cold to prevent icing up.

Evaporator Sensor

Evaporator Sensor Location

[Jay-Bruce]

Is it just me or does that sensor look like there's a whole world of hurt involved in getting access to it?

[somethingSome]

Is it just me or does that sensor look like there's a whole world of hurt involved in getting access to it?

The evaporator box sits under the dash. If the whole box needs to come out it's a dash out job.

[JimiEZ]

The only sensors on the system are a Blown Air Temperature Sensor on the left and right side of the unit and an Evaporator Temperature Sensor, along with an Air Quality Sensor.

So I suspect that you may have a faulty blow air sensor on one of the sides confirmed by your garage.

The blown air temperature sensor measures the temperature of the flow of air passing around the sensor from - 40 °C to + 100 °C.
The evaporator temperature sensor measures the temperature as close as possible to the evaporator.

After a stationary period, and after receiving the outside temperature, sunshine and blown air sensors information, a calculation estimates the passenger compartment temperature.

This is the Blown Air Temperature Sensor:


This is the Blown Air Temperature Sensor (right):


This is the Blown Air Temperature Sensor (left):


Now I'm not saying this is the cause, but if your A/C specialist has diagnosed the temperature as being off the scale of one of these, then is stands to reason that this may be the cause of the system shutting off the A/C. Of course it could be the evaporator sensor, that again may be switching off the A/C if it thinks the system is too cold to prevent icing up.

Evaporator Sensor


Evaporator Sensor Location

Thanks a lot! That's exactly the kind of information I was looking for. Though now I just have to locate the sensor... Having already removed the glove box and one of the footwell side panels, I've located the air flap motor actuators and it seems to sit pretty close to that, so I probably just have to dig around a bit.

Is it just me or does that sensor look like there's a whole world of hurt involved in getting access to it?

It sure does. I hope it's the temperature sensor, because it seems at least a bit easier to access. Not too keen on removing the whole dash...

[JimiEZ]

Small update. This thing just keeps getting weirder and weirder.

The worst of the heat passed so I wasn't too hard pressed to figure this thing out, so I've living without a glove box for some weeks now. Today, I finally kicked my lazy bum into action and figured I'd look into this again.

Luckily enough, I found a repair manual that had visual instructions for replacing the blown air sensor. Can't say that the instructions are overly instructive, but better than nothing. According to the guide, one should be able to find and remove the sensor thusly:

Ok. So I go in again, paying especially close attention to any wiring to clue me in to the location. Yet, try as a might, there's just nothing there even remotely resembling the alleged sensor.

At this point, I decided that I'd finally take a look on the pollen filter (was fine) on the driver's side and see if I'd have better luck locating the blown air sensor on that side, again following the exact same repair manual.

Lo and behold, there it is, as clear as day. Really easy to distinguish from the wiring and clear metallic sheen of the sensor itself.

There's just nothing like that on the passenger side vent, which got me wondering: is it possible that despite what the repair manual says, there's just one blown air sensor in the car? Or is the passenger side sensor somehow deeper in the vent? Should I try just replacing the driver sensor?

[GiveMeABreak]

There are 2 of these and they are the blown air temperature sensors. One on each side.

[JimiEZ]

There are 2 of these and they are the blown air temperature sensors. One on each side.

I know there's supposed to be two of them, but I just can't for the life of me find the one on the passenger side. Having located the sensor on the driver side, I now know exactly what I'm looking for, but it just simply isn't there on the passenger side. I mean I is it possible that the repair manual is wrong and the passenger side sensor is in some different vent, instead of the one going to footwell?

Here's a closeup of the interior in the passenger side vent:

No shiny sensor rods to be seen anywhere...

[GiveMeABreak]

Right Side (18)

Left Side (17)

Blown Air Temperature Sensor

[JimiEZ]

I don't know what to tell you, except that it's simply not there. I've checked quite thoroughly. The diagrams are plenty clear where the sensor should be and, as said previously, I now know exactly what I'm looking for. However, the vent on the passenger side just doesn't have the sensor.

I've been trying to find more information about it online and I came across some mentions that at least the C6 has two different AC systems depending on when they were made, Visteon on something else and apparently at least some of these systems appear to have just one internal sensor probe. There also seems to be quite a bit of confusion in terms of what the readers report as passenger side, given the LHD/RHD configurations.

Further circumstantial evidence can be found on this spare part website that appears to claim that only a relatively short run of vehicles (OPR/ORGA 11277 to 12119) had two sensor, after which it says "QTY 1". For reference, my ORGA number is 13282, which would further indicate that there might indeed be just one sensor in my car.

However, how on Earth a dual zone system is supposed to work with only a single sensor, I haven't got the faintest idea... In any case, the part seems relatively cheap, so maybe I'll just try changing out the one that I am actually able to locate and see if that makes a difference...

[JimiEZ]

I'm now absolutely and entirely certain that the Visteon system I have, has only internal temperature sensor, located on the driver side. The passenger side temperature value must thus be a somehow derived from other parameters, which leaves us with either a software problem (or a trickier hw one), or that the one existing sensor it has needs to be replaced. I dug the sensor out from the driver's side and it looks like this:

Text stamped on the front says "PA66F30" which I think is the material. Text and numbers on the side are pretty much unintelligible. This leads to my second problem. Even if I wanted to change the sensor, I can't find the replacement par anywhere. Sites like Autodoc offer parts that are obviously completely wrong, while others (mostly online junk yards) offer parts that look similar (like this 6445XF) but not quite the same. For example that one looks too long and has an extra hole in the end. Significant and would it still work? No idea.

Oh well, guess I'll just to live without cooling from now on.

[GiveMeABreak]

If you need an original, genuine part number or part diagram, and can't already find the info you need on the Forum, we do ask for a membership upgrade for official parts data as we are in turn charged for this. It will cover you for future part number requests for up to 2 years, so excellent value.

If interested, links are below, then pop your VIN up.

A response to your question by a Forum Admin requiring parts or additional information requires you to have made a current contribution (£10 min.) to the Forum.

To Upgrade Your Membership & Donate Click Here For Further Information About Vehicle Parts and VIN Numbers Click Here

[Paul-R]

But could you trust the system to present a correct part number as it seems that everything so far has indicated that there should be two sensors and in practice there's only one?

[GiveMeABreak]

That's irrelevant really as the parts are the same number.

There may well be some bulletin that was issued to dealership workshops years ago if they were indeed reduced to one sensor, but the current live data still shows 2, which it would have to do to cater for versions that have both. This all assumes of course there is 1 and not 2 of these on the OPs vehicle.