B2119

Code

Other B — Body

Compressor Failure

Brand: Other

Type: B — Body

Views: UK: 33 EN: 49 RU: 28

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Page language: EN

Causes

Electrical fault in compressor control circuit (blown fuse, failed relay, open/short wiring, poor connector)
Compressor clutch coil open/short or clutch failure
Internal mechanical failure of the compressor (seized bearings, broken vanes/scroll)
Low or incorrect refrigerant level causing pressure switch to inhibit compressor
Faulty pressure sensor or control module commanding disable
Excessive current draw or intermittent engagement

Symptoms

No A/C cooling or reduced cooling performance
Compressor clutch does not engage when A/C is requested
A/C system cycles rapidly or cuts out intermittently
Audible noise from compressor area (grinding, squeal, knocking)
Blown fuse or tripped circuit related to A/C
High current draw from compressor circuit or MIL/BCM fault messages related to HVAC

What to check

Retrieve freeze-frame and all HVAC-related DTCs with a scan tool; note conditions when code set
Visually inspect fuses and A/C relay(s) in fuse/relay boxes
Check connector at compressor for corrosion, damage, or loose pins
With A/C requested, verify compressor clutch engagement (listen/observe)
Measure battery/system voltage during A/C request (low voltage can inhibit clutch)
Measure clutch coil resistance and continuity at the connector

Signal parameters

Compressor clutch coil resistance: typically ~2–8 ohms (vehicle-specific; consult manual)
Clutch control voltage when commanded: approximately 10–14 V (battery voltage) or PWM 0–100% duty (for some systems)
Compressor current draw: rough range 5–40 A depending on type; excessive or zero current indicates fault
Low-side pressure (static with system off): typically 60–90 psi depending on ambient; running low-side often 25–45 psi, high-side 150–350 psi (vehicle/load dependent)
Pressure sensor output/voltage: typically 0.5–4.5 V (manufacturer-specific)

Diagnostic algorithm

Connect a scan tool, record B2119 and any related codes, and review freeze-frame data to see engine speed, battery voltage, ambient temp, and requested A/C state.
Confirm basic electrical supply: measure battery voltage at rest and while cranking; check all A/C fuses and the compressor relay; replace if faulty.
With A/C requested, observe whether clutch engages. If not, attempt to energize clutch directly (bench test or supply 12 V to clutch coil) to isolate electrical vs mechanical failure — only perform safe bench tests and follow OEM procedures.
Measure clutch coil resistance at the connector and check for short to ground/short to power.
Measure voltage at the clutch connector while A/C is commanded. No command voltage points to control/ECU/relay issue; command voltage but no clutch movement indicates clutch or mechanical fault.
Use an ammeter to measure current draw while compressor is commanded; compare to expected range. High current suggests internal mechanical damage or seized bearings; zero current suggests open circuit.
Check refrigerant pressures with manifold gauges. Low refrigerant or open pressure cut-out switch can prevent compressor operation. Verify pressure sensor/switch operation with a scan tool or component bench test.
If clutch is mechanically engaging but compressor not building pressure or makes abnormal noises, suspect internal compressor failure and consider replacement and oil/refrigerant service.
Inspect wiring harness for chafing, corrosion, or water ingress. Wiggle tests while monitoring voltage/current can reveal intermittent faults.
If electrical and mechanical tests pass, examine climate control module/BCM outputs and related software updates. Clear codes and retest under similar conditions to confirm repair.
Follow refrigerant recovery, evacuation, and recharge procedures and local environmental regulations if compressor replacement is required.

Likely causes

Blown A/C fuse or failed compressor relay
Damaged wiring or corroded connector at compressor clutch coil
Compressor clutch not engaging due to worn coil or air gap out of spec
Compressor internal seizure or damaged internal components
Low refrigerant pressure or stuck pressure cut-out switch
Faulty refrigerant pressure sensor or climate control module/software fault

Fault status

⚠️ Status

Compressor failure detected — compressor did not operate as commanded or abnormal current/pressure condition observed. DTC set when control circuit, clutch engagement, or compressor output is abnormal.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours