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Discussion Starter #1
Hi All

I live in the UK but we keep an Alfa 159 3.2 Q4 Ti in Tunisia, where my wife is from. She has just gone out to Tunisia with the kids and discovered that the 159's AC is not blowing cold (a bit of a problem in 40 degree heat!).

She took the car to the local VW garage (there's no Alfa garage anywhere nearby) who checked the gassing and confirmed that the system is pressurised and gassed. They then plugged the car in to diagnostics and received error code B1908 accompanied by the words (in French, so I am translating) "temperature sensor (short circuit)". The VW garage is a bit reluctant to investigate further at the moment as they are simply not familiar with 159s, so I am trying to give them some more direction.

Looking at the 159 manual it seems that the only temp sensor inside the 159 is behind the vent on the main climate control unit. Are there any other sensors that could be at fault? It seems to me that I should instruct the garage to remove the climate control panel and look for obvious wiring faults, and if they find none, I should provide a replacement unit. But, I don't want to do that and then find that the problem persists!

Have you encountered this error before? I have googled it a bit and found a couple of people who seem to have had this error code/problem, and they found problems with the wiring on the circuit board behind the climate control unit. But those were on russian and czech forums so the google translate was dodgy.

If you are familiar with this code and the likely cause/fix, please do let me know - I will be going out to Tunisia to join my family at the end of next week, so that would be an ideal opportunity to take any parts out there if required to get it fixed.

Many thanks in advance for your advice.
 

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Discussion Starter #3

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If it is the temp sensor that is faulty then the air should blow cold if you switch the system temperature to "LO"
 

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Discussion Starter #6
If it is the temp sensor that is faulty then the air should blow cold if you switch the system temperature to "LO"
Thanks that's interesting. I would have thought my wife/the garage would have tried that already. Difficult when i can't nip outside and try things out myself, being several 1000 miles away! I'll check with the wife just in case.
 

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Step 1: check to see if there is any leakage in the system. Fluorescent dye can help you with this work. In fact, if there is a heavy leakage, there will be no pressure. Just use a gauge to check the PSI level in the low-side valve.

Step 2: check if the compressor is turning; start the car and turn on the AC; find the air conditioner compressor to see if it is on. If it is on and the blower is on but the pulley is not turning, you can have the idea that the clutch of compressor is not engaging. The main reasons for causing such problem are bad fuse, wiring problem, broken AC switch or low on refrigerant.
Step 3: there are several other problems that an auto AC many encounters are bad switches, fan belt problem or seal problem
Step 4: there is another situation that there is cooling in car but not cool enough. You can guess that the pressure may be low and you just need to add refrigerant or pollen filter is blocked.
 

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Discussion Starter #8
This one also says the same: http://www.carobdcodes.com/?s=B1908
Very strange, are you sure the error code is just something unrelated??
could it be for a different model or something? Here are the posts i found with the same code and same error message my wife sent me. You might have to use the browser translate facility!
Êëèìàòðîíèê - ãðåøêà B1908 - Club Alfa Romeo Bulgaria
Errore B1908 sensore temperatura aria abitacolo - Alfa Romeo 159 Owners Club
 

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Discussion Starter #9
Step 1: check to see if there is any leakage in the system. Fluorescent dye can help you with this work. In fact, if there is a heavy leakage, there will be no pressure. Just use a gauge to check the PSI level in the low-side valve.

Step 2: check if the compressor is turning; start the car and turn on the AC; find the air conditioner compressor to see if it is on. If it is on and the blower is on but the pulley is not turning, you can have the idea that the clutch of compressor is not engaging. The main reasons for causing such problem are bad fuse, wiring problem, broken AC switch or low on refrigerant.
Step 3: there are several other problems that an auto AC many encounters are bad switches, fan belt problem or seal problem
Step 4: there is another situation that there is cooling in car but not cool enough. You can guess that the pressure may be low and you just need to add refrigerant or pollen filter is blocked.
Thanks. Apparently the garage has checked the pressure/coolant levels. Not sure about the rest - as just mentioned it's a pain that I can't check the car myself but am trying to deal with this remotely!
 

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check if the compressor pulley is engaging & check fuses as 1st option? Difficult for your wife of course unless you can talk her through it over the phone, then again she may be a right petrol head??
Are the fans coming on when you put air con on? If not, fuse or relay?
You just know it's going to be something stupid (hopefully) just difficult when you can't actually see the car!
 

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Discussion Starter #11
Unfortunately no...she's not! and yes it's tricky doing it remotely. I'll be there in a couple of weeks, but in 40 degree heat the car's unusable until sorted so I'd like to get it sorted out for her before I arrive. Also, any parts it might need will need to be carried out there by yours truly, which could be problematic if I can't diagnose it in advance. As you say probably something stupid....but then again I would have thought the VW garage would have done all the basic checks. Thanks for the advice though! From what I understand, fan/blower is working, just not cold.
 

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Discussion Starter #13
the garage is insisting that it's the internal temperature sensor that needs changing, despite what the grimjeeper said about the lo setting. The problem is I can't find via google such a part. Is it only available as part of the CC unit or something?
 

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Does the blower work at all? If not at any temp then the fan circuit may be compromised - the resistor on top of the A/C fan (under the passenger dash) is known to overheat and melt the connector.
A bit fiddly to clean it all up but a cheap fix
 

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Discussion Starter #17
no not yet - my wife / the garage hasn't been able to sort it out. They told me to buy the interior temp sensor. So I have bought the sensor and mini blower thing from a chap on ebay (as recommended by another thread in here) and am travelling out to tunisia on Friday. We will see if it works! I'll update the status in due course.....
 

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Discussion Starter #18
So....just arrived in Tunisia and set off to take the car to the garage, with my sensors ready for swap. BUT then I noticed on the way there that when I floor it, the AC blows cold (and i can hear a dull whine noise from, presumably, the compressor). This leads me to believe that despite the error code that the garage is reporting, the problem is not with the sensor/sensor fan. Would you agree that it's not worth even trying to swap those bits? From my description do you have a good idea what the problem may be? Seems to me it's compressor related - maybe belts? or compressor itself? Any suggestions appreciated!

I am a bit annoyed with wife/garage for not noticing this very obvious characteristic of the fault, as I can now not nip back to the UK for a different part, so looks like i'll be stuck out here for 2 weeks with no AC......
 

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Discussion Starter #20
Checked that and it's not the gas. I saw the diagnostic output and it is indeed saying faulty interior temp sensor......it just goes against my (admittedly lacking) logic that it would be the sensor if the AC switches on under full throttle.
 
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