The A/C in my car doesn't work, before any repair, I try to understand which part in the A/C system is the problem.
Here the symptoms:
Everything looks fine: no error message, the interior ventilation blows, etc... but not cold
The pressure is ok: I've made a gas refill in specialized shop
No leaks (checked at the shop)
The big external fan of the A/C never start (the one at the front of the motor)
I think the compressor and the A/C clutch are working properly. At full stop, if I switch on the A/C the instantaneous fuel consumption increase from 0.5 L/h to 0.7 L/h. It decrease back to 0.5 L/h when the A/C is switched off. I assume it means the compressor is running, am I right?
Maybe it's a faulty sensor? It would explain why the big external fan of the A/C never start?
I've tried the Forscan OBD software to read car's data.
I have a P0531 default, which is about A/C pressure sensor, but seems to may be linked to other issues.
I've read some sensors data from the OBD, a lot looks normal. Here are all values from the HVAC module:
The "PCM.PBDACCE" (A/C clutch engaged") value switch from disabled to enabled when I turn on the A/C.
The OBD can read also 3 A/C related pressures values:
"PCM.AC_PRES" (A/C pressure sensor) which is 0.2 kPa (A/C off) to 0.4 kPa (A/C on)
"PCM.CACRP" (corrected air conditioning refrigerant pressure) which is 158 kPa (A/C off) to 389 kPa (A/C on)
"PCM.ACRPSV" (A/C refrigerant pressure sensor A voltage) which is 0.68 V (A/C off) to 1 V (A/C on)
I also have various "out temperature" values "ABS.OUTTMP", "DDM.OUTTMP", "IPC.OUTTMP", "PCM.OUTTMP", "PCM.OUTTMP", "PDM.OUTTMP", "PSCM.OUTTMP" and "SASM.OUTTMP".
All have the same value (about 30°C which is correct) but "ABS.OUTTMP" and "PCM.OUTTMP" have -19°C value. Is it a faulty sensor? Do you know which one?
Any help to find the correct part to be changed? A temperature sensor? The pressure sensor? The compressor?
How can I test if the A/C pressure sensor is working (it's a 3-wire one)?