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Discussion Starter · #1 ·
Have had my 2012 Giulietta for about 20 months now. I love it. The first problem I've had with it just started recently. The aircon wasn't kicking on as it should. I had it regassed last year at the dealer and thought they must not have found a leak when compression testing it. Unfortunately, it's something different.

I now take my car to an independent garage because there is no Alfa dealer in town and the Fiat dealer in town is not much of a winner. I trust my mechanic, but he specializes in Mercedes (our other car is a Merc) and he doesn't have a ton of Alfa experience. I brought the car into him and he found that the gas level was good, but the compressor was not kicking on because a temperature sensor that he called the frost detection sensor was preventing the compressor from kicking on. He says the sensor is soldered in and, the best he can tell, Alfa only sells the sensor as part of a costly loom that would require the entire dash to be removed to replace. He's waiting on Alfa to get back to him if that's true but cleaned the sensor and it functions most of the time now. The other sensors for the dual-zone climate control function as expected.

The sensor is to the left of the driver's footwell (I'm in the UK, so that's the center tunnel) somewhere near the cabin air filter. It was reading -5 degrees and needs to read at least 5 degrees for the compressor to kick in. After cleaning it the sensor reads about 10 degrees even in ambient temperatures above 20. Obviously needs replacing. He's happy to replace it with whatever compatible part we find. We both prefer the OEM option if possible, but anything that prevents removing the whole dash is going to be the winner.

Does anybody know what part he is referring to, if it has a part number separate from the loom, or, if it doesn't, what would be a compatible replacement? Mechanically inclined, but not a mechanic myself, so will dig around and take pics or something if you can point me in the right direction. I have a multimeter and can provide readings if necessary. Thanks.
 

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I have the same issue on my 2014 Sportiva. Had the system gassed and tested but it was ok. Then it works every other time I drive the car -- drives me mad. If you have any chance pointing out the position of this sensor with a picture I can clean it out and test it/look for a replacement and ofcourse provide some feedback to you.
 

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I don't know if I've suffered a similar issue, at the start of this summer I thought my car might need a re-gas but after about 2 weeks of not doing anything my aircon has worked really well for about the last month. I'll have to connect the laptop to the car and see if there are any errors that may point to this "frost sensor". Might even be something like a blocked condensate drain? In which case the evaporator coil may be frozen over causing the sensor to actually be frozen. Anyone know any better?
 

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What’s the pollen filter condition as a blocked one with poor airflow will also cause freezing
Without hijacking his topic, I took out the filter and left the filterhouse open for a while -- no problems. Then left the filter out and closed the filterhouse -- problems started again. The search continues:nerd:
 

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What you need to verify somehow is if the evap temp sensor is actually reading correctly and evap is icing or if it’s rogue readings.

If it’s doing it’s job and evap is icing then you will be looking at air flow problem over evap or the TEV is not functioning correctly in my opinion.
 

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What sort of TEV does Alfa fit to the G? The mechanical versions are usually very reliable so unless its an electronic version I'd be surprised if it was the TEV. Thinking more like a clogged evaporator, strange how it works okay with the housing opened?
 

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No idea on the G but my 159 had mechanical one so would expect the G to be the same.

The pollen filter cover being open has allowed more air flow over evap to keep temp up.
 

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What you need to verify somehow is if the evap temp sensor is actually reading correctly and evap is icing or if it’s rogue readings.

If it’s doing it’s job and evap is icing then you will be looking at air flow problem over evap or the TEV is not functioning correctly in my opinion.
I will look into this, I have ordered a new filter to start with. Next step is using MES to check these readings. That is currently handicaped by bloody MES failing to connect with the yellow cable. Need to sort that out first... already went the long way with drivers and settings, I can scan with the ELM connected but when I use the colored adapters it won't connect anymore :disappointed:
 

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Had the same problem, in the end resolved by an (apparent) recall solution which presented the dash to go out.
At least that is what the dealer told me, it was luckily still under warranty.
I was confronted with the issue whilst being in italië with over 40°C.

Apologies but I do not know the part number of the part replaced.

Hope this helps you
 

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Without hijacking his topic, I took out the filter and left the filterhouse open for a while -- no problems. Then left the filter out and closed the filterhouse -- problems started again. The search continues:nerd:
So after a few days I noticed the AC does no longer switch on/off every other drive. In my mind I have developed this theory that it took the system a few days to reset itself and evaporate moist as it must have had this blocked filter in it for like 3 years (I think the filter i took out was made in '16). I will put the new filter in asap and continue to monitor this issue, I would love to luck out on this one:glasses:.
 

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To update on my AC issues, without a filter in the housing it kept on switching so I was not too optimistic. Last week I received the new filter and went to install it on fridayevening. While I was putting it in the housing I noticed 2 wires out of a "plug" in front of the casing. I guess it is the tempsensor, took it out and cleaned it. Ofcourse I put it back in and for the past three days the system has not yet failed me...
 

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Discussion Starter · #15 ·
Pardon the delay in replying... Haven't had much time to look at or work with the car the last couple weeks. The pollen filter is a few months old now but gets replaced with regular services. I spoke with the garage that had originally pulled the codes and they said there had been another fault that popped as well for one of the motors in the climate control system, but they weren't sure if that was a one-off or it was a persistent issue as my complaint didn't seem to match that fault. Turns out it is probably the motor as well.

Whatever motor directs the air past the heater core or the aircon is likely the fault, since I have been able to reproduce the issue. The worst time I could reproduce it, I turned the heat on full blast and was unable to get the system to stop blowing hot air after that (except for turning it all the way off, of course). When I turned the temperature all the way down and put on the aircon, the car ramped up the blower speed as if it expected that it would be cold air coming out the vents, but it was just hot, hot, hot. If I matched the temperature on the climate control system to the inside of the car temperature, the blower slowed down. Sometimes it seems it can control this motor and other times not. It must be beginning to fail.

As far as loose wires near the pollen filter, nothing has been knocked off and the garage told me that the sensor was soldered on, so if there are loose wires something was ripped off, not unplugged. I was able to get a sympathetic Alfa parts department (they do exist!) on the phone to talk through it, but we didn't come up with much without pictures. The only thing they know of in that area is the humidity and smell sensor. Of course, that just shows up as "sending unit" on Alfa parts diagrams as do almost all sensors. Is the parts department mistaken? Does anyone know if there is more than one sensor in the footwell? My guess is it is part of the whole blower apparatus and Alfa expects the whole thing to be replaced for a sensor gone bad.

The car is back to the garage today complete with a wiring fault in the boot loom now, too. Hopefully, this isn't the beginning of bad things...
 

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Discussion Starter · #17 ·
That's it! That's the sensor. Just had the garage send over a photo. After they cleaned it, the sensor is no longer throwing codes. For future reference, does anyone know if there is a part number for this thing or does it only come as part of the whole loom? I'd like to save anyone else with this problem some time. It may just be me if the sensor throws a fault again.

Additionally, for any people who stumble on this in the future, there's a higher-res color photo of the sensor attached. Note that the car is a RHD model so this is in the center of the car down near the cabin air filter. Cleaning it with some electronic components cleaner was all it needed.

Unfortunately, the car has thrown faults for three motors in the climate control system now. Supposedly that necessitates pulling the dash off to check the wiring loom and then replacing any motors as necessary. Not sure if it's the loom or the motors at this point. Should be a cool £300 in labor plus £60 per dead motor apparently... Any chance this could be the climate control computer instead of the motors?
 

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Hi all, I believe I have this issue. If I remove the sensor and hold it between my fingers to warm it up the compressor kicks in. I've sprayed it with contact cleaner but hasn't made any difference.

Does anyone know where I can see the sensor readings in MES? I think it must be reading much lower than it should and the car thinks it is below zero, but can't find a sensor that looks 'out'?

Has anyone managed to work out if this easy is replaced without a whole loom?

Many thanks, all 👍

956125
 

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To me that looks like a normal PTC or NTC thermistor. Can you measure the resistance across the two legs of the sensor, or are there any markings on it (would be in the yellow area)?
 
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