Powertrain
generic / SAE
P255F
A/C Request A Circuit Range/Performance
The A/C request input A is electrically intact, but its value does not match the system context — for example asserted while the HVAC controller reports off, toggling rapidly, or sustained while compressor pressures cannot support it. The ECM disables A/C clutch engagement until the input becomes plausible.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 5F
Possible causes
- HVAC module sending inconsistent request high
- Sensor element aged beyond calibration window low
- Sensor mounting loose - signal damping low
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–500 €
- Estimated time: 0.4–2 h
- Component: ac request input a
- Component: hvac module
- MIL / check engine light
Sources
References
sae:J2012