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Discussion Starter #1
So this yoke: Servicebox-Sedre calls it an interior air thermistor, Servicebox calls it a Hygrometery temperature, Diagbox calls it a humidity sensor, but it seems to measure temperature!

I'm getting a fault code F702 "Passenger compartment humidity sensor fault" so I assumed it was this and I took it out and gave it a clean, grand job, it's a cool yoke with a fan that always runs and a resistor, I assume it works similar to a MAF. I'm wondering if the little grey plate at the bottom measures humidity..

Anyway, this measures the temp on the passenger side just fine (~20c at the time) but Diagbox thinks it's measuring the drivers side (I'm assuming at's a half-arsed cockup due to French LH drives) and gives a reading of 0 for the drivers side (called passenger side in Diagbox). Goddammit, I'm mixed up now...

Basically I'm wondering if there's another one of these hidden somewhere on the right hand side under the steering wheel somewhere? Since THAT side is reading 0c. Servicebox only shows one of these in all the diagrams I've seen, but Diagbox is giving me the F702 error for a sensor on the passenger side (right hand, driver-side really!).

I tested the one in the pic, and when unplugged it goes from 20c ->0c (Diagbox calls it drivers side). Car has dual zone controls. Maybe the diagrams are mixed up and they're the mono-zone diagrams or something. Think I'll have a root around under the steering wheel someday and see what's there. Didn't see anything when I was doing the heater flaps.

I said I'd stick up the pics for anyone who is looking to change or clean theirs, mine was manky. €70 from peugeot and pretty hard to find online. I used an old credit card to slide down behind the facia panel to get at the clips, from left to right, a bit annoying but doable with some patience and probably easier the second time..







 

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Both of my 407s had this code, and everything worked fine. So I didn't worry.
One even had a recurring code for a fault with the front door window modules or something along those lines. Again everything worked, so it got ignored.

Sent from my Vodafone Smart ultra 6 using Tapatalk
 

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Assuming you have independent control of the climate control on each side, then there must be two of these somewhere.
But are you having a problem with the control of temperature, or have you just done a check with Diagbox and a "fault" came up?

I had a problem with interior temp control in my 307, and found that unit had fallen off the back of the dash.
 

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Discussion Starter #4
Yea, I'm not really too bothered about it, I just like to understand the details about the car, I just go looking for problems when I'm bored!
I assume these only come into play when the 'auto' function/button is enabled? Does this auto function actually change the temperature by moving the heater flaps? I'm not sure yet since I haven't had both heater flaps working together since I bought the car. I've repaired them several times but they keep snapping again!

The last repair I done on them I melted a load of plastic all over the break with a soldering iron, plastic welding.. and then mushed and mixed and melted the whole lot together. They seem to be holding now, which is why I moved on to the temp sensor..
 

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If it does indeed have dual zone heating i would expect 2 of these 1 for each side but as above are you reading codes and chasing faults or do you REALLY have a problem.
 

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Discussion Starter #6
If it does indeed have dual zone heating i would expect 2 of these 1 for each side but as above are you reading codes and chasing faults or do you REALLY have a problem.
Looks like we both post at the same time, and I kind of half-answered you above.. lol
But, yea that would make sense alright, I'll go and have a look under the other side and see if I can locate another one. Servicebox says there's an 'evaporation thermistor, (if separate)' on the LH side, like a probe sticking into the heater box, and it only shows one "SENSOR HYGROMETRY TEMPERATURE" (lol) but doesn't show where it goes. Sedre shows this as "AIR THERMISTOR" and it's on the RH side, so I suppose I'll have a look there for another one there.. :)
 

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I have/had the same issue. When i looked on diagbox it was showing 0 C from the passenger side sensor. I got another one from a scrap yard and plugged it in, and the sensor then reported -31 C!.
The driver's side was the same at 30 C but the passengers side reported -31, is this correct? has anyone else seen it reporting negative temperatures?

Diagbox doesn't report any faults on the system any more, so as far as it is concerned, everything is ok.

cheers
 

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This is apparently an old post; not so old, but I have the same fault on a scan of my 407, and I'll want to know if anyone ever got to the root of this!

My AC has these three problems:

1. It cools at its convenience. At times, it chills very well, and you'll want it to chill if you live and drive where I live:subsaharan africa. At other times, it cools,but just enough for you to prefer the AC to the hot air outside.

2. Even though the rear air vent works well, the air at the rear is usually not as cool as that at the front of the car. This makes for uncomfortable passengers.

3. The windscreen usually mists up at the point where there is an air vent on the dashboard. This happens even when that vent is shut close.

Any pointer on this will be greatly appreciated.
 

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Its possible you have the common broken heater flap issue and the cold air cannot get to where it needs to be
 
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