P2D29

Code

Generic P — Powertrain

A/C Compressor Motor Stalled

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 25 RU: 23

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Page language: EN

Causes

Mechanical seizure of compressor (internal damage, bearing failure, seized shaft)
Electrical failure in e-compressor motor (shorted windings, internal damage)
High-resistance or open power supply (fuse, relay, connector, wiring)
Ground fault or poor ground connection
Compressor clutch failure or air gap excessive (for belt-driven compressors)
High refrigerant pressure causing hydraulic lock

Symptoms

A/C cooling reduced or stops when compressor commanded ON
Compressor does not spin or clutch does not engage
High amp draw from A/C circuit or blown circuit protection
Unusual noises from compressor (grinding, growling) or no noise if seized
Possible engine stumble or increased load when compressor command applied
MIL or A/C warning light and stored DTC P2D29

What to check

Retrieve freeze-frame and full DTC list; note conditions when fault set
Visual inspection: wiring harness, connectors, fuses, relays, and grounds
Check refrigerant system pressure (static and when commanded on) with gauges
Listen for compressor operation and inspect belt condition/tension (if belt-driven)
Measure battery voltage at compressor connector with A/C commanded ON
Measure compressor motor current with clamp ammeter during run attempt

Signal parameters

Compressor command signal (PCM/ACM): ON/OFF status (logic level or CAN command)
Compressor motor supply voltage: ~battery voltage (12 V or system voltage) when ON
Motor control PWM duty cycle (if applicable) and motor current (A)
Compressor RPM or motor speed feedback (if present) — expected >0 when commanded
Refrigerant high/low pressure readings (psi/bar) — should be within normal range
Current sensor or fuse-trip threshold reading — compare to factory stall/current spec

Diagnostic algorithm

Verify and record DTCs and freeze-frame data. Clear codes, then reproduce fault by commanding A/C ON and observing.
Perform a visual and connector inspection for damage, corrosion, loose pins, blown fuses and failed relays. Repair as needed.
With A/C commanded ON, measure voltage at compressor power connector; should be near battery voltage. No voltage indicates control or supply fault.
Measure ground integrity at compressor ground. Clean/repair poor ground connections.
Measure current draw with clamp ammeter while compressor is commanded ON. Compare to spec. Stall/overcurrent indicates mechanical lock or shorted motor.
Check refrigerant pressures with gauges static and during operation. Extremely high pressure or locked pressures indicate hydraulic lock or blockage.
Attempt to rotate compressor shaft by hand with system depressurized and belt removed (if applicable). If shaft cannot turn, compressor is mechanically seized — replace compressor.
If shaft turns freely and current is within spec but control reports stall, inspect/current-sense circuit, motor controller, and associated fuses/relays. Check for intermittent wiring (backprobe while moving harness).
If e-compressor motor shows shorted windings or insulation failure (resistance out-of-spec), replace compressor assembly.
After repairs, evacuate, recharge A/C system to spec (if opened), clear codes, and verify proper operation and no recurrence.

Likely causes

Internal mechanical seizure or bearing failure in compressor
Shorted or damaged e-compressor motor windings causing excessive current
Blown fuse/failed relay or poor connector causing intermittent power
High refrigerant pressure (overcharge, condenser blockage) preventing rotation
Faulty current-sense or motor control electronics reporting stall erroneously

Fault status

⚠️ Status

Stored when compressor motor is commanded ON but motor speed is zero or motor current exceeds the stall threshold. The system detected a stall condition or inability to rotate the compressor while running.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours