P1544

What it means

P1544 on a Chevrolet means the A/C Refrigerant Condition is Very Low. The engine control module has judged that the air conditioning system is not holding enough refrigerant, usually from the pressure sensor signal or A/C pressure readings falling below the expected minimum. The ECM then normally stops the compressor from engaging to protect it.

Symptoms

• A/C blowing warm or only slightly cool air
• A/C compressor not engaging or clutch not clicking in
• A/C clutch cycling on and off rapidly
• Check engine light on, possibly with an A/C warning message
• Hissing or oily residue near A/C pipes, joints or the condenser

Possible causes

• Refrigerant leak from a pipe, hose, joint, condenser, evaporator or compressor seal leaving the charge very lowlikely
• Faulty or leaking Schrader valve or service port cap or sealpossible
• Faulty A/C refrigerant pressure sensor or its signal giving a falsely low readingpossible
• Damaged wiring, corroded connector or poor earth at the pressure sensor circuitpossible
• Blockage or restriction in the orifice tube or expansion valve causing very low suction-side pressurerare
• Internal ECM fault misreading the A/C pressure inputrare

How to diagnose

1. Read the stored codes and freeze frame data, noting ambient temperature, engine speed and A/C request status, and check for other A/C or sensor codes.
2. Visually inspect the A/C pipes, hoses, condenser and compressor for oily residue, damage or signs of a leak.
3. Inspect the pressure sensor connector and wiring for damage, corrosion, loose pins or chafing.
4. Connect a manifold gauge set and check static and running pressures against the manufacturer's specification for the model and refrigerant type.
5. Compare the live pressure sensor reading on a scan tool with the gauge readings to see whether the sensor is accurate.
6. Check the sensor's supply voltage, reference and earth with a multimeter against the wiring diagram.
7. Use a UV dye or an electronic leak detector to locate any leak.
8. Check for a restricted orifice tube or expansion valve by looking at temperature drops and pressure readings across the component, following the model-specific procedure.

How to fix

• Repair or replace the leaking component, then evacuate the system, check it holds vacuum and recharge to the specified refrigerant type and weight.
• Replace the faulty Schrader valve, service port seal or cap.
• Replace the A/C pressure sensor if its signal does not match the gauge readings.
• Repair damaged wiring, connectors or earths in the sensor circuit.
• Replace the blocked orifice tube or expansion valve, along with the receiver/drier or accumulator as the system requires, and flush where specified.
• Replace or reprogram the ECM only after the wiring, sensor and refrigerant charge are confirmed good and the manufacturer's procedure calls for it.

Can I keep driving?

This code for other makes

• P1544BMWPedal Position Sensor
• P1544BuickA/C Refrigerant Condition Very Low
• P1544CadillacA/C Refrigerant Condition Very Low
• P1544ChryslerA/C Refrigerant Condition Very Low
• P1544GMA/C Refrigerant Condition Very Low
• P1544GMCA/C Refrigerant Condition Very Low
• P1544OldsmobileA/C Refrigerant Condition Very Low
• P1544SaturnA/C Refrigerant Condition Very Low
• P1544SubaruHigh Exhaust Temperature Detected
• P1544VolkswagenThrottle Actuation Potentiometer Signal Too High

Nearby codes

• P1543ChevroletA/C System Performance
• P1545ChevroletA/C Clutch Relay Control Circuit