Fiesta 2012 AC issue

[sorted]

Hi chaps, could really do with some help on this please, belongs to daughters partner, as above a 2012 4cyl petrol- not sure what size - with manual basic AC, not climate.
AC packed up suddenly, dash telltale lights when button pressed but nothing else. He’s taken it to a local garage assuming it needed a regas but they said pressure is fine and probably needs compressor!

I managed to spend a short while only on it tonight. AC relay has full time live and ignition live (so fuses OK) and if I give the control side of the relay it a ground the compressor kicks in and you get nice cold air. Fans run too. So issue is with control circuit and this is where I struggled. I connected Forscan which seems to read everything OK and I get most live data etc. But I can’t find anything about AC- I can find all the other HVAC controls for front and rear screens etc in the BCM and they all show in live data, but nothing for AC controls or data like pressure. Had to give up for the evening at this point, will be a few days before I see it again.

So can you learned chaps please help with 3 points:
1. Does this have a specific HVAC module- if so the inability to connect to it may be the issue, where does it hide?
2. If not, where should I be able to see these PIDs?
3. Could anyone PM me a wiring diagram for this- I can’t find anything online to see where the pressure switch links in and so on, despite lots of googling.

Oh and any other ideas really welcome!

Thanks in anticipation.

[OldGit]

Can't help with a wiring diag as my ETIS password has long expired - this might help though

workshop-manuals.com/ford/fiesta_2002.25_11.2001/mechanical_repairs/4_electrical/412_climate_control_system/412-00_climate_control_system_general_information/diagnosis_and_testing/climate_control_system/

Personally, if 'everything' works when you energise the relay then you're backfeeding an earth to something that is looking for it to bring in the engine cooling fan, if the AC light is staying on, then I'm fairly sure that means the refrigerant pressure switch is OK - you could disconnect it to check that theory....

[remmington]

Wiring diagram sent via email.

[sorted]

I realise this goes back a while now but I have only just been able to spend some time on this one and thought I would close it out.

With the aid of the wiring diagram so kindly supplied by remmington I was able to go through end to end and find what turned out to be a broken wire between the evap sensor and instrument cluster, meaning there was no feedback signal being seen. Quick solder and heatshrink later and it sprang happily back into life with nice cold air, just in time for a run to Heathrow next weekend. He’s very pleased.

So many thanks for the help- again!

[remmington]

Aug 5, 2022 16:04:57 GMT 1 sorted said:

I realise this goes back a while now but I have only just been able to spend some time on this one and thought I would close it out.

With the aid of the wiring diagram so kindly supplied by remmington I was able to go through end to end and find what turned out to be a broken wire between the evap sensor and instrument cluster, meaning there was no feedback signal being seen. Quick solder and heatshrink later and it sprang happily back into life with nice cold air, just in time for a run to Heathrow next weekend. He’s very pleased.

So many thanks for the help- again!

Well done - cheap fix!

(no parts required just time - just how I like it when working on my kids cars as they never pay me for the bits)