B11FF

Code

LAND ROVER B — Body

Air conditioning refrigerant pressure

Brand: LAND ROVER

Type: B — Body

Views: UK: 19 EN: 28 RU: 17

AI status

Completed

ready

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Page language: EN

Causes

Low refrigerant charge (leak)
Overcharged system or trapped high pressure
Faulty refrigerant pressure sensor (transducer)
Damaged wiring or poor connector/ground to sensor or HVAC module
Failed compressor or compressor clutch not engaging
Blocked condenser, receiver/drier/accumulator or expansion valve

Symptoms

Reduced or no cabin air conditioning cooling
Compressor cycles rapidly or does not engage
AC-related warning or message on dash
Erratic HVAC behavior (temperature swings)
DTC B11FF stored in body/HVAC module and possibly related freeze-frame data

What to check

Retrieve all stored codes and freeze-frame/capture data from HVAC and engine modules
Inspect visible AC system components for oil residue or physical damage (hoses, condenser, fittings)
Check fuses and relays for HVAC/AC compressor circuits
Scan live data: refrigerant pressure sensor values, compressor request vs actual, condenser fan status, ambient and inlet temps
Measure refrigerant pressure with a calibrated manifold gauge set on high and low sides (compare to spec)
Backprobe sensor connector and check supply voltage, ground and signal with multimeter/scan tool

Signal parameters

Pressure sensor raw value (kPa or bar) shown in module live data (compare to spec)
Sensor signal voltage (typical range 0.5–4.5 V depending on sensor) — verify reference supply and ground
High-side and low-side pressures from manifold gauges (model-specific expected ranges)
Compressor request signal from HVAC/ECM (on/off or PWM) and actual compressor clutch voltage
Condenser fan ON/OFF or duty cycle, engine RPM, ambient temperature
Related CAN messages between HVAC and engine modules (if applicable)

Diagnostic algorithm

Step 1: Read and record B11FF and any related codes from all modules; note freeze-frame data and conditions when fault set.
Step 2: With scan tool, view live refrigerant pressure sensor values, compressor request, condenser fan status and ambient temps. Look for inconsistency between commanded and measured states.
Step 3: Perform a visual inspection for obvious leaks (oil traces), damaged hoses, collapsed lines, and check condenser for blockages. Verify fans operate when AC is requested.
Step 4: Check fuses/relays and verify power and ground at the pressure sensor connector. Backprobe sensor: confirm reference voltage and ground, then measure sensor signal while cycling AC.
Step 5: Use calibrated manifold gauges to measure actual high- and low-side pressures at operating conditions. Compare pressures to manufacturer specification to determine undercharge/overcharge or blocked flow.
Step 6: If sensor electrical fault indicated, test wiring for continuity and intermittent faults, repair wiring/connectors as needed, then retest sensor signal. Replace sensor if out of spec.
Step 7: If low refrigerant is confirmed, perform leak detection (electronic sniffer, UV dye, or smoke) and repair leaks before evacuating and recharging to correct charge per spec.
Step 8: If pressures indicate compressor is not producing pressure despite requests, test compressor clutch operation, clutch coil resistance and supply voltage; replace or repair compressor as required.
Step 9: After repairs or component replacement, evacuate, vacuum and charge the system to manufacturer specification; then verify system operation and clear codes.
Step 10: If fault persists with correct pressures and good sensor/wiring, investigate HVAC control module software/calibration and CAN communication; consult manufacturer technical service information.

Likely causes

Pressure sensor electrical fault (open/short/intermittent)
Actual low refrigerant due to leak
Compressor not switching on (no clutch engagement) causing abnormal pressure
Blocked airflow through condenser (debris/fan fault) causing high pressure

Fault status

⚠️ Status

Air conditioning refrigerant pressure fault — sensor/circuit or system pressure out of expected range.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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