DS3 Air con not working

[Dardvl]

Hi all, hoping for some help of the experts here after spending alot of hours checking, googling, speaking to people and more checking.... I have purchased a 2014 DS3 sport 1.6Turbo and the air con is not working.
By that I mean that the when the fan is turned on and the A/C button is pressed, the compressor is not kicking in.

I have had the air con guys check it out and have confirmed that there is gas in there and the system is pressurinsed.
I have checked fuses in BSI (Glove box area) and PSF (Engine bay)
I have checked and replaced the engine cooling fan module
I have traced wirring to ensure they are not unpplugged, cut or melted etc,
I have popwered on the compressor clutch separately and have confirmed it enagages when powered separately.
I have checked the engine temp sensor and found to be ok. Temps read normal i.e. cold and operating temp. If unplauuged the radiator fan turms on.


I have been told if the turbo coolant pump is not working or the thermostat it can downgrade the air con and stop it from working.
Wirring to both items is intact, what further checks can be done here? Do I power on the pump separately to see if it works? (5a fuse is good)
Is there a way to test the thermostat?

The codes that I get are:
P2602
P0598
P0599
P0691- Airbag and unrealted to this however I including for reference. (no air bag warning light on dash)


Any help on how to proceed further would be greately appreciated.

[xantia_v6]

Do you hear the coolant pump running for a few minutes after switching off the engine when at normal running temperature? P2602 indicates a failed pump.

The other tricky fault is the heating element in the controlled thermostat. If that fails it will prevent the compressor clutch from engaging. P0598 and P0599 indicate that problem. You can try fitting a 50Ω resistor in place of the thermostat heater to suppress that error.

If the above fault codes were intermittent, then it may be that they were triggered while you had things unplugged.

[Dardvl]

Hi, thank you for the reply.
No I dont believe I have heard the pump run after the engine has shut down. Can I power this up with 12v to check?
The codes have been there since I bought the car and do not clear.

I ll try the 50 ohm resistor to test it out. Is it possible to measure any voltages at the thermostat housing i.e. 12v etc or resistance across the heater element? ( I am getting 12 ohms currenlty and 0V on either pin of the plug side, engine had been off for 2 hours)

Is there any other way that I can force the air con to ensure there are no issues with the air con?

Thanks for all your help.

[xantia_v6]

I think that the pump talks to the ECU, so not easy to test. When I needed one I found that they were cheaper if bought for BMW/Mini.

If you power the compressor clutch directly, the return line to the compressor should get cold within a few seconds, but I would not recommend prolonged use as it overrides all the protection mechanisms.

[Dardvl]

i did power up the clutch but nothing seemed to chil. I am told the regulator valve also needs to be operated to work...
frustrating ... I ll get to the bottom of it hopefully

Thanks

[PaulC5]

The engine fan will also need to run to condense the refrigerant.

[Dardvl]

Hi, i put the resistor on as described and apart from it getting really hot, the fault did not clear or the air con worked... the search continuos..

[Dardvl]

Have now replaced the thermostat housimng and the electic water pump... no change at all...
Air con still not working and still the same OBD faults....