Ambient Air Temp reading +50C

[Time Searcher]

Just moved to sunny Portugal, good trip down with no problems at all, motorwise. In the last fortnight the Instrument panel Air Temp sometimes indicates +50 deg C when the outside air temp goes over +30 deg C. I've looked at the Haynes Manual and it looks as though it is just an indicator, ie is not used as a control for anything else, could this be confirmed, please? No other temperature problems, Gerry Tee fitted, Hans Temp Gauge works as it says on the tin (gives me a lot of confidence now) no loss of fluids at all. Very occasionally after this condition has occurred and I have switched the engine off, on restarting the gauge indicates the +50 and the heater switch for the rear window indicates ON. The Air Temp gauge sometimes drops back to what I would expect it show but then steps back up to +50. I shall have a tweak at the wiring this morning to see if that makes any difference. outside air temp was +22 C at 8 oclock and climbing, not complaining though;)Any thoughts on the subject would be greatly appreciated..

Cheers, Martin

[Simon]

The outside temperature sensor is used for the automatic climate control so if it is reading inaccurately then it may affect the climate control performance.

I would think that the temperature sensor (located in the front bumper) has probably fell off it's mounting point. When this happens it can sometimes dangle nearer the radiator than normal and therefore pick up the temperature from that rather than the ambient air. Refitting the sensor I think requires taking the bumper off, but I'm not entirely sure - it might be possible to do without but I've never had to do it myself so can't comment from experience.

[T-Cut]

- - - - - it might be possible to do without but I've never had to do it myself so can't comment from experience.

It's possble apparently. Raise the front on ramps and remove the flimsey triangular plastic underpanel mounted on the bottom edge of the bumper and the wheel arch lining. I think the driver's side would be closest. You can reach in to get at the sensor/clip. If it's still in position, I'd swap it for a new one.

TC

[Time Searcher]

Thanks Simon,
I have had a look at the sensor mounting, I can just reach the thing from underneath, and have checked that it is where it should be and it is... the wiring disappears into that of the fog and spot wiring. No sign of chaffing anywhere and would you believe it, working properly at the moment. Mrs Time searcher is off to town this afternoon so I will get her to monitor it. The air con appears to be working when the sensor is at +50 or reading correctly.
I am aware that the lower default, possibly due to disconnection ie open circuit is -30C, could it be that +80C is the short circuit default?

Cheers, Martin

[GreyGhost]

I'm pretty sure the A/C does not use a reading from the outside temp sensor. It uses the sunlight sensor and the vent to the right of the centre console to manage it's operation. (Expert please confirm or deny)
I'd plump for a faulty external temp sensor.

[Time Searcher]

The Sensor seems to have a mind of its own. Goes for several days OK but then varies between correct ambient and +50C. I took it off the car on Saturday and the Inst. Panel showed an expected -30c. So I put the sensor on an ohm meter to see what the resistance was. It was about 1100 ohms and steadily rose to about 1800. I decided to put it in the freezer to get it really down, checked again after about 15 minutes and it was about 500 ohms. However, it suddenly went to short cct. and then came back to reading about 1K. I would guess that the short cct. position is the +50C. on the car.
Put it back on the car where it immediately indicated +50c. later back to reading correctly.
I have tried to source one from the usual suppliers by looking at websites but have now asked my son in Huddersfield to try to get one from a breaker's yard. [he is coming to visit at the end of the month]. I have given him a picture of the part and position from the 'Russian' website where it gives JFT100160A as the part number but reading elsewhere I see that JFT100180 is an alternative, will either do for my 05 Tourer?
Cheers,
Martin

[T-Cut]

You got the lettering wrong. Here's current Rimmer info:

JTF100160A has been superseded.
Now use part "JTF000180"

Part Number JTF000180
Description SENSOR-AMBIENT AUTOMATIC AIR CONDITIONIN
Retail Price £15.32 inc. VAT (£13.32 exc. VAT)

TC