Air con turning on by itself

[chops]

Annoying problem with my 156, the air con just turns on by itself. Mostly happens within the first 10 minutes of a trip, none of the auto settings on but the air con just starts up, press the button to turn it off and then the fan goes up to high speed and I have to turn it down. Sometimes happens 3-4 times in the first few minutes of driving. Anyone else had this issue?

[John Hanslow]

Soulds like an error as it is doing the demist sequence.  

How about just leaving the climate control set on and adjust the temp to your general liking.  It is really set and forget as I never turned mine off.  

Just let it do its thing - I actually believe it will wear out less by having it on instead of turning it off - and its automatic anyway and worked a treat.

Not a technical answer but a practical one.

[colcol]

Re aircon, my 02 JTS 156 has dual climate aircon, and for the first 5 minutes it seems to do what it likes, BUT, you have to remember if it is on auto then all the sensors for temperature and pollution and moisture, it will send the cold air to where it is needed most, and if it senses moisture on windscreen it will switch to demist mode and if it is colder outside it will bring air in from outside, then if its hotter outside than inside it will recirculate the air, then if it polluted inside it will bring in fresh air, then drive through a tunnel full of diesel fumes and it will go back to recirculate, this gives you the impression its got a mind of its own! one thing to make sure that the pollen filter isn't blocked, these should be changed on a regular basis, otherwise airflow will be poor, on the series 1, 97-02 the pollen filter is in the engine bay on the left hand side under the windscreen, on the later models 02-06 the pollen filter is inside on the left side in the passenger footwell, Colin.

[wankski]

i haven't had that problem but i'm 90% sure its the control unit.

You have 3 rotary dials to control the climate control. this is actually connected to 3 optical sensors to tell if you've rotated the knobs... the pcbs have been made very poorly (big surprise) and often the solder fails on the optical sensor connection to the PCB of the mainboard controller.

In this case, i believe its the middle sensor for the middle knob causing the issue, it is shorting and thus thinking you've turned it on! it also controls fan speed so when u mess with it, it's thinking you've rotated full on etc...

For the other two sensors, it will randomly select a temp or gradually increase the temp cf what u selected... all the same issue - just depends where it strikes...

plan of attack if you can be bothered - remove climate control assembly from console (remove gearstick gaiter, ash tray and stereo) - then remove pcb and inspect all solders, and resolder as necessary.

good luck.

[chops]

i haven't had that problem but i'm 90% sure its the control unit.

You have 3 rotary dials to control the climate control. this is actually connected to 3 optical sensors to tell if you've rotated the knobs... the pcbs have been made very poorly (big surprise) and often the solder fails on the optical sensor connection to the PCB of the mainboard controller.

In this case, i believe its the middle sensor for the middle knob causing the issue, it is shorting and thus thinking you've turned it on! it also controls fan speed so when u mess with it, it's thinking you've rotated full on etc...

For the other two sensors, it will randomly select a temp or gradually increase the temp cf what u selected... all the same issue - just depends where it strikes...

plan of attack if you can be bothered - remove climate control assembly from console (remove gearstick gaiter, ash tray and stereo) - then remove pcb and inspect all solders, and resolder as necessary.

good luck.

Too much effort for what is just an annoyance, guess I will just live with, thanks everyone in this thread for the tips

[colcol]

The air conditioner blower on my JTS and the control unit, that is the part that sits under the radio with 3 round chrome knobs is not made by Alfa\Fiat, but are DELPHI, which used to be General Motors Electrical Division, but in those days it was called DELCO, but the General found nobody would buy electronic parts, especially Ford, off them, so they spun it off into a Managment Buyout and changed the name to DELPHI, years ago it filed for chapter 11? and went bankrupt, it got going again, just thought you might like to know that, Colin.

[wankski]

OH FFS!! now i have this problem.... not the middle knob, but the other two... they escalate in temp rather rapidly....

ok...haha, if i do pull the trigger on my radio upgrade i'll buy some real leather gaiters and go to town with a full write-up 'how-to'...