2010 Mk 7 air conditioning fault.

Hi, hope you guys can help. My daughter's 2010 Fiesta (I believe it is known as the 2008.75 model) had no hot air, I suspected a broken blend flap actuating arm and was correct, the actuator mounting lugs were also broken. Fixed that (no access!) but using my Forscan and laptop to check the system the air con is requested on pushing the button and the compressor cuts in for a while (30 seconds) then cuts out.

The cabin temperature has been at '215°' all the time, this is what my SMax reads with air con switched off. I changed the sensor, took the old one apart to see how it worked (it appeared to be working as it should) which made no difference. I changed the sensor by the evaporator as it was easy (old one also appeared to be working normally) and I also tried another control panel/HVAC module, also no difference. It is the automatic climate control version.

Thinking now that it was a wiring fault I joined this forum to download a diagram (HVAC not in Haynes manual unless I've missed it) and checked continuity to the cabin temperature sensor thermistor which are the green and green/blue wires. There was no continuity from Pin 11 to the sensor (green/blue) so I unwrapped the loom insulation to expose the wire. No damage so I suspected the plug pins and took apart the HVAC module plug (has a swing over keeper lever). The reason for the discontinuity is that the green/blue wire is in Pin 12, Pin 11 is occupied by a brown/violet wire (power I think). Pin 12 is supposed to be a green earth from the sun load sensor.

Looks like I couldn't swap the pins round if I wanted to so she will be getting the car back with only manual heating control and no air con.

Is this a mistake from the factory? Has the air con never worked (the lights do come on giving the appearance of working)?

Many thanks, Gary

Is the AC properly charged and not leaking coolant?
If that's not the case, start there.

It's an old car. The AC might need a refresh.

Yes, regassed very recently. I can see the refrigerant pressure rising when the compressor cuts in.

I've put it back together so she can have the car back. I tried HVAC module reboot and self-test, no problems.

My S Max ran out of refrigerant this summer in Germany, of the many things that trigger a DTC low refrigerant pressure is not one of them!

This is the plug to the HVAC module, the pins are marked on it and they're also marked on the back of the module.

I think you're on the right track - it may deal with the Sun-load sensor being faulty.

The Automatic and the broken actuator also leads me to think the powering of the Sun-load sensor with. Either thru a power fault or other failure including wrong unit used...

Read this thread, see if it can lead you to fix this problem.
https://www.fordfiesta.org/threads/what-is-this-please.9785/post-27727

The Sun0load sensor comes in two types of connectors that are also different coloring - so if the Climate control seems to be stuck it may be due to the sun-load sensor has failed.

It does have a sunload sensor, can't remember seeing it in Forscan but I'll have a look.

Doesn't look the most accessible part to change!

One of the parking sensor speakers failed on my S Max, was behind the instrument panel, major strip out.

It may need only to remove the APIM display, the Radio Head unit and that keypad to expose the innards - and see the connector to the Sun-load sensor.

The one I've got was a simple pop out so you just had to push in one of the tabs to tilt and lift it up to get it out (which totaled mine but I had bought a new one) due to the old one wouldn't make the lights comes on, just the instrument panel would darken under the long wide bridges I'd drive under but never would turn on the lights - sunrise or sunset - even at night- required me to manually turn the switch.

I first replaced the switch, that wouldn't restore the Auto function - so then I went after the Sun-load sensor and that's how I found out about those notches in the different sensors. Needed the one just for the lights and inside temp - but not the Auto-Climate control. So if the Climate control has gone to thinking one temp all the time, then when I had to visit the parts stores they did recommend that you replace the Sun-load sensor at the same time you check for blown fuses - for it can force the fuses to blow and in doing so, also take out that sensor too. Especially if was working before those actuators bit the dust.