During these cold months I want to be able to cheat the Outside Temp. Sensor into believing it's hotter than 0 degrees celsius .

If temp. is 0 or less then I am not able to turn on A/C.
Yes I can click the button and it lights up, but the little frosty logo on the climate display does not appear = A/C is not allowed on.

NOTE: It's the automatic dual zone climate version.

I called FIAT about this during my first Winter and they told me it's normal and that other car makers use the same system... Does an A/C system really die if turned on in -5 degrees celcious? I don't believe it so I want to cheat a little :devil:

Want to install a variable resistor somewhere between the outside temp.sensor (in the sidemirror) and the Climate Control Unit. With this I should be able to cheat the car into thinking it's hotter outside.

QUESTION:

Haynes wiring diagram 12*24
I am guessing that D031 is the plug between passenger front door and frame. But where is D008 which seems to be a plug between D0031 and the control unit? It's hard to follow the bundle of wires cause they are split up and gathered along the way between door and centre console?

Hej, replied on the other thread so here are the Drawings from eLearn again, looks there is not D008 …

MvH, Bernie

Hi Bernievarian!

Uploaded the page from Haynes I was writing about.

Pointing on D008 on the page with Auto Climate A/C?

On same page right now I just saw D008 just above the Fan Speed Variator - something tells me I just fiddled with that cable earlier today (another thread about my problem with fan speed suddently dropping down).
And again I just woke up and saw D008 just a thumbs length above the D008 I am pointing at.

Earlier today I found a big blue/black plug just behind the trim-sidepanel at passengers lower leg towards the middle. Must inspect the colorcode on the wires to see if this is the plug?
If yes I should have lots of space to hide my little cheat switch without having to route cables from far away

Is there usually an indication on the plugs to what their name should be?

https://www.dropbox.com/s/7uibucnapmaul5e/Billede%2011-12-2018%2011.59.26.jpg?dl=0

Hej,

the D008 connector in Hayne's manual correspond to D021 on the eLearn schematic …

MvH, Bernie

Hmm found out that the Haynes colorcode on the one of the two wires to the outside temperature sensor was wrong!!!
Cables are Black/Violet and Blue/Green or something. Luckily checked cable color at the plug in the mirror instead of cutting cables in the cabin first...

BERNIEVARIAN: I guess I'll forget about locating that plug - whatever it's called. I will just cut the 2 wires near the entry to the cabin at D031 and fit my button+resistor around this area.

Only have a little variable resistor (with maximum 10k Ohm) for testing at home so fittet this to the open plug in the mirror. Keeping the temperature sensor out of the loop I get around 30-40 degrees with the variable resistor at max (10k Ohm).

Some people probably already know but writing this so I will remember and others who read the thread can use it:
Outside temp. sensor has lower resistance at high outside temperatures => and higher resistance at lower outside temperatures.

Found a little neat button with dual contact sets that will enable me to either choose from the Outside temp. sensor reading or (by pressing the button) cutting away the outside temp. feed and only reading through a little resistor with around 10k Ohm.

Will post pictures once I am done (maybe tomorrow?)...

The reason AC doesn't work below that temp.. is actual physical limitations... the lines ice up below a certain point.
Have a look

Talked with a colleague a few hours ago and he told me the same thing.
Some systems can deal with it and some can't... and of course this one is not setup for it!

I will still install the button and keep in mind only to use it shortly (when I REALLY need it) and not if it's lower than something like -3 or -4 outside.

During winther we most often just have a few minus degrees in the morning during winther and a little plus in the middle of the day. Snow doesn't last long around here.

I understand that there is a small risk of damaging the system, but if I don't turn on A/C for 3 months I think I am at higher risk of having dried out seals.

Am I right assuming you want the AC to dry the air Inside the cabin (defrost) ?

MvH, Bernie

Yes dry the air so I wont get a build up of moisture on the inside when I sit there breathing and heat storming out of my big winter jacket.

If it’s very cold I use a de-icer spray on the outside before opening the doors. And in between I try to keep the inside of the windows free of grease by wiping them with mirror/glass cleaner.

On my way to work today I noticed something weird.

The wires to the outside temp. sensor is cut (because I am not finished with my little cheat project), så the outside temp info in the dash display says "---".
This is of course because there is no connection to the sensor.

But seems like I am still allowed to turn on A/C?
I get the little frosty logo in the Climate display when I try to turn it on. I was thinking that with a "cut away" sensor I would surely not be able to turn on A/C?
This means that I can just install a simple button and can skip the part with a resistance?

When cheating I would rather have "---" in the display then a wrong digit.

Can someone confirm that if the frosty logo is present in the Climate Display that actually equals that A/C is really on!?

You can check if the compressor runs (clutch engaged... or signal on compressor wire)

The system might run.. but will turn off pretty fast.
Pipe will freeze, pressure will rise system will turn off.... the only thing is it will have horrible efficiency.... i think that is in fact the only reason for fiat implementing this (and maybe longer life for the compressor).

A bit of theory Guys ? How do it work ??

The AC compressor compress the gas, this hot gas is tranfered, thru (hot) pipes to the expanser (located in the car's heat unit area), arriving there it expands and its pressure goes down thanks to the large volume it gets in. To expand it needs calory that it extracts from the surrounding area: that is where the 'cold' is created, then the expanded gas which has been warmed by the surround (while expanding) is sucked back to the AC pump where it's compressed again, and the cycle continue …

So there are a hot and a cold line going to/from the AC compressor, the cold one being potentially subject to froze in cold weather ( I honestly doubt about that), which is why Fiat and other car makers disable the AC when it's minus outside …

Cheers, Bernie.

I would understand if it wouldn’t work on the northpole... But at just a few degrees minus. I’ll take a chance and see how it goes

Bernievarian said:

A bit of theory Guys ? How do it work ??

The AC compressor compress the gas, this hot gas is tranfered, thru (hot) pipes to the expanser (located in the car's heat unit area), arriving there it expands and its pressure goes down thanks to the large volume it gets in. To expand it needs calory that it extracts from the surrounding area: that is where the 'cold' is created, then the expanded gas which has been warmed by the surround (while expanding) is sucked back to the AC pump where it's compressed again, and the cycle continue …

So there are a hot and a cold line going to/from the AC compressor, the cold one being potentially subject to froze in cold weather ( I honestly doubt about that), which is why Fiat and other car makers disable the AC when it's minus outside …

Cheers, Bernie.

Click to expand...

No

The compressor, compresses the gas, as a result the gas heats up, the gas passes to the condenser, where the airflow through the radiator cools it back down while keeping the gas at pressure. The gas flows in to the cabin where it is expanded in the evaporator (or via an expansion valve) the act of expanding the gas takes energy out of the gas causing it to become cold, the temperature of the gas is now significantly lower than the air outside of the evaporator and so the energy in the air is transferred in to the now cold gas. However this is not a lot of energy and the gas is still cold relative to the surrounding atmosphere. The gas then passes usually to the dryer/receiver, a storage tank for excess gas and contains moisture absorbent medium to remove any moisture that has somehow gotten into the gas, the receiver is a larger capacity as well so usually this results in further expansion of the gas making it colder still. In the summer, this is usually where all the condensation drips from under the front of the car.
Then the gas is back at the beginning and is drawn back towards the compressor.

If you run the aircon when the outside temperature is too cold, you can get ice on the eveporator, this doesn’t cause a lot of problems to the aircon system, however the airflow from the cabin fan is blocked and this can burn out the cabin fan.

Because the gas going back round the system is already cold and already dense, the compressor doesn’t put much heat into the gas, there is an element of expansion of the gas within the condenser, if the gas is already cold and dense and expands a little in the condenser, what happens is the condenser can start to ice over, this leads to the car’s engine radiator not getting any airflow and so the car can over heat.

If there is moisture in the gas, this can freeze as well causing damage internally to the compressor or to the rubber seals if moisture starts to force them open.

Some cars are much more advanced and have ways to monitor the temperatures around the system and prevent icing, fiats system is pretty dumb in that respect so if you bypass the systems designed to stop it icing over then you risk damaging the system or the car.

It’s also worth noting that what you propose is pointless. If you override the aircon to clear a misty damp windscreen. The moisture builds up on the evaporator, until sufficient water builds up to drip off and follow the channels out of the cabin and on to the road. As soon as you turn off the aircon the hot air flowing through the vents will soon warm up the moisture on the evaporator, blowing it back onto the windscreen.

Essentially fiat designed it that way as the most efficient and best way of operating that system. To bypass it would be of no benefit at all.