Ds5 No A/C even after replacing pressure sensor

[Cypresix]

Hello everyone,

I have a 2012 Citroën DS5 (1.6 thp) and my air conditioning still doesn’t work after replacing the pressure sensor.
• System has been leak-tested and re-gassed – pressure is fine.
• Compressor itself works: when I feed it direct 12V, it engages and blows cold air.
• At the compressor plug I only measure ~1.3V when A/C is switched on (engine running).
• Pressure sensor has already been replaced, but still no change.
• All fuses checked – OK.
• I suspect the BSM (under-bonnet fusebox), maybe the relay/FET output is faulty, but I don’t know which pin is supposed to feed the compressor clutch.

Does anyone have a wiring diagram or pinout for the BSM on a DS5, or experience with low voltage at the compressor?
Is this a common BSM failure?

[mickthemaverick]

When you filled the system with refrigerant did you also replenish the system oil that you will have lost replacing parts?

[Cypresix]

When you filled the system with refrigerant did you also replenish the system oil that you will have lost replacing parts?

yes they did first 25 min vacuming. then 5ml oil / 5 ml uv and 450g refrigerant.
the ac worked when we hooked up the compressor with 12v directly from the battery. but somehow its not getting 12v from the control unit

[mickthemaverick]

OK, so the voltage at the compressor is not right I'm sure. You said you tested the compressor directly with 12V and it works, I assume you mean the clutch operates? Does it actually engage and drive the compressor round? There are shims of varying sizes involved in the compressor clutch and may be giving trouble but that wouldn't account for the 1.3V. Have you tried connecting the 12V direct to the compressor with the engine running?

[Cypresix]

OK, so the voltage at the compressor is not right I'm sure. You said you tested the compressor directly with 12V and it works, I assume you mean the clutch operates? Does it actually engage and drive the compressor round? There are shims of varying sizes involved in the compressor clutch and may be giving trouble but that wouldn't account for the 1.3V. Have you tried connecting the 12V direct to the compressor with the engine running?

yes we tested it with engine running. the ac worked. Cold air came in

[mickthemaverick]

OK then so the problem would seem to be either your aircon switch/fan switch or the BSI control circuitry. You need to get a diagnosis done to identify the problem or you could go chasing yourself round in circles. As you measured 1.3V my guess would be the power feed relay contacts if there is one or a wiring fault but if within the BSI the only way forward is a diagnosis, although you could try a BSI reset according to this procedure but I doubt it will help.

[xantia_v6]

The engine ECU can also disable the compressor. You need to get all fault codes read and cleared, and if that doesn't work, then check the live data parameters in both ECUs to ensure that neither has disabled the compressor, and if that looks Ok, then you probably have a faulty BSM.

[Cypresix]

The engine ECU can also disable the compressor. You need to get all fault codes read and cleared, and if that doesn't work, then check the live data parameters in both ECUs to ensure that neither has disabled the compressor, and if that looks Ok, then you probably have a faulty BSM.

I have a simple obd reader. Do I need special psa diagnose?

[xantia_v6]

You need a diagnostic tool that understands the relevant Peugeot ECUs, and can make live readings of parameters. There are several mid range diagnostic tools that can do this.

[Cypresix]

You need a diagnostic tool that understands the relevant Peugeot ECUs, and can make live readings of parameters. There are several mid range diagnostic tools that can do this.

Can I measure anything from the pressure switch? It’s showing me 5v constantly but no variation.

Or my fan from the condenser? I don’t remember when it was spinning for the last time?

[Cypresix]

I just checked the fan. Its getting 13v but It’s not spinning.
Please tell me that this is the issue…

[Cypresix]

Update
next to the cooling fan is a resistance relais that changes the speed of the fan. I bypassed this relais and the fan started working on full speed. This unit must be damaged. Im replacing this tomorrow. This might be the issue with my AC because the ecu cannot control the fan.

[Cypresix]

new Update,
resitor relais from the cooling van replaced. Van works properly now. Still no AC

[xantia_v6]

It is possible that an ECU error code needs to be cleared after fixing the fan. This may happen automatically after a few run cycles, or may need a code reader.

[Cypresix]

It is possible that an ECU error code needs to be cleared after fixing the fan. This may happen automatically after a few run cycles, or may need a code reader.

I have to wait weeks for an appointment. Which code reader do you recommend me to buy? Affordable