I hope these are better

Much better pictures.
But I can't see anything on the boards that would cause a problem, no burning, deterioration the board etc

So the next step would be to check the output voltages from the board which you could try with your meter set on voltage across the two output terminals which go to the fan, you know the inputs of 12v, earth and the request signal is good on the 4 pin connector at the other end of the board so see what is happening at the output.

The circuit board has 3 x 3 pin ICs on one side and 2 ICs and a coil on the other which will be the timings/ logic so that looks like it's going to be a closed feedback pulse type speed controller ie it's going to pulse 12v on/off very rapidly to get the fan motor to run at different speeds and the feedback from the motor ensures a very accurate and monitored speed control so you may or may not be able to see what''s happening with a simple meter as it's not quick acting enough. But anyway, see what you find. If requesting max speed then I'd want to see steady max of 12v across the output terminals

Here's how they work but don't blame me if your eyes glaze over
http://homepages.which.net/~paul.hills/SpeedControl/SpeedControllersBody.html

You'd need to have the CB connected to the fan to check feedback voltages from the fan motor but otherwise you should see the output voltages.

Now if the circuit board is putting out the right stuff then there's a problem with the motor

Thanks, I'll do that.

Something I think I forgot to mention, is that it never seemed to work on FULL AUTO, that would come on when the car was started, and then would go off after 10s or so, along with the aircon.

Meaning that it would say FULL AUTO on start up, and then go to AUTO.

Ok , I reconnected the CB to the loom, put a MM across the o/put connectors of the CB that would feed the i/put to the fan itself, and turned ignition on and turned the climate control fan from min to max:

Min o/put of CB = 12.26V
Max o/put of CB = 12.17V
Range from max to min stepped up in 0.01V increments.

Then I measured across again, this time with the fan connected:
Min o/put of CB with heater fan connected = 2.45V
Max o/put of CB with heater fan connected = 2.9V

When I repeated this with the ground to the seat mount bolt:
Min o/put of CB with heater fan connected = 11.82V
Max o/put of CB with heater fan connected = 11.8V

MM across Pin 1 = 0.01V min and max(?) earth of CB and seat mount bolt.

Max o/put request speed voltage (Pin2), earth o/put CB, fan connected = -3.31V
Min o/put request speed voltage (Pin2), earth o/put CB, fan connected = -8.16V

Max o/put feedback voltage (Pin1), earth o/put CB (fan connector), fan connected = -8.72V
Min o/put feedback voltage (Pin1), earth o/put CB (fan connector), fan connected
= -9.2V

Is the fan at fault, as when it's not connected, there's about 12V on the CB output for it, but it drops right down when connected?

It sounds as if the CB is at fault for although it's supplying 12v at the output then it has no power ie current so one or more of the amp semiconductors on the CB may have become cooked.You know the fan is ok as you put 12v across it earlier and it rotated at full power.

Imagine the voltage as being the size of a water pipe and the current is the flow of the water inside . The pipe size is ok but there's only a trickle of water flow so it has very little power.Volts x Current = Power
The flow is so inadequate that it is the equivilent of having a smaller pipe and that's why you see the voltage drop when you connect the fan

What are my options then, £200 new fan? Or can I get just the CB? Scrappers maybe, but I won't know for sure if the scrapper one will be ok

I would get a 2nd hand one, maybe from Ebay, as they're hard work enough to remove so have someone else do it for you and if it doesn't work then you can get your money back

I guess the scrappers it is then Thanks once again for all your help with it, I've learnt more about fault finding and electrics! :worship:

Do any of the other Fiat models share the same heater fan?

Unbelievable, I eventually got round to getting another fan, second hand, went through the agony of fitting it, and it worked! Good powerful air flow, climate control working with the FULL AUTO lit up, snowflake button lit up, and it lasted a day before reverting back to the original issue of weak fan output and all the above not lit up on the display! :bang: I'm starting to resent ever buying this car, why does it all have to be so complicated? Any ideas anyone? I suspect somethings not right and maybe frying something on the PCB for the fan.

Ha! Don't lose heart, you've got one part of the system working now and it's showing up a weakness further down the line. That's quite common, fix one thing and another shows up. Sounds like your earth point C16 is weak. I would try a test parallel earth, (more simple than it sounds) simply bridge the heater connector pin 3 black earth wire to your own good earth somewhere nearby

So grab some spare wire the same size or bigger and connect pin 3 to a good earth point somewhere close by on the car

If it all comes alive then you know the problem

Ok, I 'll try that. Incidentally, the next day, it seemed ok again, on manual, all the way to work which is an hour's drive. I put it on full auto on the way home, and it seemed to die again after 20 min or so.
Back in the car today, 10 min on manual fine, then dropped out a couple of times. Did it again couple hours later on another drive.
Sounds like what you say about the weak earth, if only I could find that C16, I can't see it on the drivers side unless it's buried under a load of stuff.
Thanka again!

Erm you are aware that on Full Auto the fan speed will slow down to a trickle once the temperature you select has been reached, aren't you?

Hi, yes, I'm aware of that. It's behaves now like my old fan did. Recently, I had one day where it blew as it should, then went back to crap again.

I recently found this in an old thread:

'If the recorded [COLOR=#f77e1d !important][FONT=inherit !important][COLOR=#F77E1D ! important][FONT=inherit ! important]battery[/FONT][/FONT][/COLOR][/COLOR] voltage is lower than the threshold, the computer cuts in via the CAN [COLOR=#f77e1d !important][FONT=inherit !important][COLOR=#F77E1D ! important][FONT=inherit ! important]network[/FONT][/FONT][/COLOR][/COLOR] to send a signal to disable a series of appliances: this includes the fan control.'

I measured the voltage on the battery today, 12.42V with ignition off, 14.03V with engine running.

I still haven't got round to extending the earth to the seat mount bolt.

RIGHT! I've put a wire from the earth feed and clipped that to the seat mount bolt, made no difference.
A week ago the fan suddenly came on in FULL AUTO mode and the fan blew happily.
I wonder if it's something other than the fan.
I say this because when I start the car, I get FULL AUTO with the climate control snowflake button lit, and then it goes to AUTO within say 10sec.
This has always been the case.
The only difference between this fan and my old one has been that I've actually had this one working briefly; with the old one I never had the system in FULL AUTO.
Could it be the digital control itself?:bang:

Stilo climate control

Hi, climate control issue, any ideas anyone?

I get FULL AUTO with the climate control snowflake button lit, and then it goes to AUTO within say 10sec, aircon snowflake button then doesn't do anything. The fan blows gently.
This has always been the case.
I recently put another, 2nd hand fan on, worked for a few days, FULL AUTO, then back to normal ie. AUTO with weak fan.

I've put a wire from the earth feed and clipped that to the seat mount bolt, as suggested - made no difference.
A week ago the fan suddenly came on in FULL AUTO mode and the fan blew happily.
I wonder if it's something other than the fan.

The only difference between this fan and my old one has been that I've actually had this one working briefly; with the old one I never had the system in FULL AUTO.
Could it be the digital control itself?

really old treath but...anyone has this problem solved??...i have the same...i`ve tried everything written here even before i read it...:slayer:...i was at the point of changing the fan but stopped when found this... sooo if anyone can help thanks in advice...

If you connect to the climate control ECU by using MultiECUScan and an ELM327 cable, has it recorded any fault codes?

The difference between FULL AUTO and AUTO is usually that FULL AUTO has the air conditioning compressor on. I wonder if a low refrigerant charge might cause the system to revert to AUTO and lose the fan speed in the process. Perhaps get the refrigerant pressure checked/topped up before continuing.

That motor-control article brings back horrible memories of long hours I spent in a university lab programming PID loop control. Now I can't even remember what PID stands for. Had something to do with integration/rates of change...

-Alex

So it's been a little time since i last wrote but...I have fixed the problem...and there is what i did...
1. I checked if there is a difference in the fan for different models etc. clima or automatic climate control...
- There is a difference. Models with simply climate control have a special resistor that controls the fan speed by the switch (from 1 to 4)
- Models with automatic climate control have a much complicated fan WITHOUT a resistor. All the controls are in the motor.
2. I checked if there is a difference in the fan for cars made in different years...etc. 2001 2004 2007...
- There is a difference. Models till what i found April 2003 are equipped with Siemens fan. And all other models after that are equipped with Denso fan. Also the small motors for airmix are different...Siemens and Denso.
As you allready know Denso is much better than Siemens...so...I bought a Denso fan made July 2004 and one for my cousin made August 2007...Changed them both. His Stilo is 2002 1.6 5D...
1. Month later we both doesn't have anymore problems with fan...no errors...checked with latest MEScan

So if you have this problem...buy yourselves a fan DENSO...and look for it in cars made after 2003 - 2004...there is a sticker with Denso on it...Also Siemens are all black plastic...Denso is half black, half white...and Siemens DOES NOT have sticker with the name...


Hope this helps to someone...