Technical Stilo MW 1.9 jtd air con

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Technical Stilo MW 1.9 jtd air con

Alyons74

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Hi All,
My 2003 Stilo MW 1.9 jtd has had a problematic fault with the fan/air con for a while.
The fan only runs at half speed and the air con doesn't come on.
Sometimes it all runs normally.
Diagnostics didn't pick up anything and I've changed the pollen filter.
Thinking it could be a sensor or blockage.
Any help would be appreciated.
 
When you say "Diagnostics didn't pick up anything" which diagnostics do you mean? My Stilo air con does not work and there is no MIL dashboard light to indicate a fault but the software available here for free
( www .fiatforum.com/stilo/216751-fiatecuscan-diagnostic-software .html )
plus a USB ELM327 from ebay did find the fault code in the ECU as P0530 which is the pressure switch on the air con pipe just under the offside headlamp. I just need a cheap source to buy a new one now ... been quoted just over £40 plus vat which for a variable resistor is a bit steep imo. ;)
 
Hi Artful.
I originally took the car to my local garage who ran ECU diagnostics but no fault codes came up. They ran a query through Fiat who said that the dash would probably need to be taken out to investigate further and even then they might not find the fault. I thought I would explore my own options before going down this route as it sound expensive.
 
I've just had the gases checked by a helpful mobile aircon chap, and they are ok. He also confirmed that the compressor clutch is turning so the compressor is probably ok. He's not an auto electrician but thinks the climate control unit in the dash could be faulty. Anyone had or heard of this?
 
Hello 1.9JTD MW Dynamic with the D/Climate etc. 53 plate feb 2004.
I'll bump on this too, my aircon has just been regassed. FiatECUscan advised I have no pressure and the aircon is showing disabled. Did have a low pressure fault from sensor, but i've cleared it. Will check wiring when its not raining. :confused:

Do these sensors fail?
How are you getting on?
D.
 
Check the signal voltage from the pressurestat.
1 = earth
2 =approx 5v supply
3 signal


signal needs to be between 1v- 4.5v before it will say OK and allow compressor to start. Clearing the fault code will just mean it will fire up again if the pressure is not giving a signal voltage within the accepted range.

You can resistance check the pressurestat. These are typical resistances with zero pressure
linear press sw 3 new one resistance figsJPG.JPG
Whatever the pressure, resistance figures 1-2 + 2-3= 1-3
 
Last edited:
Hi Artful.
I originally took the car to my local garage who ran ECU diagnostics but no fault codes came up. They ran a query through Fiat who said that the dash would probably need to be taken out to investigate further and even then they might not find the fault. I thought I would explore my own options before going down this route as it sound expensive.

My mate first tried with his diagnostic setup and it didn't find an error code but the fiatecuscan did find an error.

Artful
P0530 doesn't necessarily mean there's something wrong with the air con pressurestat. It will give that same fault code if the aircon pressure is simply too low too

Yes I know you are correct but I missed out saying I had already had the gas checked by a friendly air con guy so I knew there was pressurised gas in mine.

Check the signal voltage from the pressurestat.
1 = earth
2 =approx 5v supply
3 signal


signal needs to be between 1v- 4.5v before it will say OK and allow compressor to start. Clearing the fault code will just mean it will fire up again if the pressure is not giving a signal voltage within the accepted range.

You can resistance check the pressurestat. These are typical resistances with zero pressure
View attachment 93755
Whatever the pressure, resistance figures 1-2 + 2-3= 1-3

On mine the error was able to be cleared by fiatecuscan but reappeared after about 4 seconds even with the engine not running so the fault had to be either the sensor or aircon ecu. ... I didn't have this useful info to hand when I fixed mine but did have the diagram showing the connections so I soldered a 10K lin potentiometer to a 300mm length of household 1.00mm twin and earth bared back and then shielded to within a couple of mil of the end so I could remove the connector going to my sensor and connect this pot to the harness/ connector plug. The 10K was across the 5v and 0v and the slider was connected to the signal pin with the pot set at half way (i.e. 2v5 or half resistance) ... I then switched on the ignition, connected the fiatecuscan software and reset the fault code and it stayed out, proving on mine it was the sensor. A new one from Fiat is over £40+Vat but I found a Vauxhall Astra one from a scrap yard had the same pins and works a dream. (y)
 
just looked at Fiat eLearn sensor 5040BC note on there sensor pins 1+2 are the ends connected to+5V and Earth. Pin3 (centre offset pin) is the slider/signal output. of course when looking at plug or socket left & right swop over.
TEST- Activation/deactivation test of a/c unit by substitution of sensor by(as they advise) a 1Kohm linear potentiometer to the plug.
one end to p1 other to pin2 (L+R) adjust (center)to p3{ if it were a plocket- -female plug}-it would be easier to do!
Being linear center position will give a
2.5V signal to the unit-- a/c should run
moving to either extreme end ie.
0V out or 4.5V out will give a low pressure or too high pressure signal
a/c should drop out to protect components.(compressor drops out)
----( engine on a/con on)----
sorry just to clarify pin outs!
 
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