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P1542

A/C System High Pressure High Temperature.

  • Chrysler
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
5
AreaVehicle speed, idle control and auxiliary inputs
42
FaultThe specific fault in that area

What it means

P1542 on a Chrysler is defined as A/C System High Pressure High Temperature. The control unit has seen the A/C refrigerant pressure and the related temperature reading go above its allowed limit, so it has set the code and will normally cut the A/C compressor to protect the system. The exact sensors and thresholds used vary by model and engine, so check the manufacturer data for the specific vehicle.

Symptoms

  • A/C blowing warm or not cooling
  • A/C compressor not engaging or cutting out shortly after starting
  • Engine cooling fan running continuously or at high speed with the A/C on
  • Engine warning light on
  • Engine running hotter than normal in traffic with A/C on

Possible causes

  • Condenser airflow restricted by dirt, debris or bent finslikely
  • Cooling fan not working properly (fan motor, relay, fuse or control circuit)likely
  • Refrigerant overcharge or air/moisture in the systemlikely
  • Blockage in the refrigerant circuit, such as a restricted condenser, pipe, receiver/drier or expansion devicepossible
  • Faulty A/C pressure or temperature sensor, or damaged wiring and connectorpossible
  • Engine overheating or a cooling system fault raising underbonnet temperaturespossible
  • Fault within the control unitrare

How to diagnose

  1. Read all stored codes and freeze frame data to see engine temperature, vehicle speed and A/C status when the code set, and check for other cooling or A/C codes.
  2. Visually inspect the condenser and radiator for dirt, leaves, debris and damaged fins, and check that nothing is blocking airflow at the front of the car.
  3. Inspect the A/C pressure sensor wiring and connector for damage, corrosion, poor pins or chafing.
  4. With the A/C on, check that the cooling fan(s) operate at the right times and speeds, and check the related fuses and relays.
  5. Check engine coolant level and condition, and confirm the engine is not running hot.
  6. Connect a manifold gauge set to measure high and low side pressures and compare them with the manufacturer specification for the ambient temperature.
  7. Compare the live sensor reading on a scan tool with the measured gauge pressure to see whether the sensor is accurate.
  8. Check for temperature drops across the condenser, pipes or receiver/drier that suggest a blockage.

How to fix

  • Clean the condenser and radiator fins and straighten or replace damaged parts so airflow is restored.
  • Repair or replace the faulty cooling fan, relay, fuse or wiring.
  • Recover the refrigerant, evacuate the system and recharge it to the exact specified quantity if overcharged or contaminated.
  • Replace any blocked or restricted component, such as the condenser, receiver/drier or expansion device, then evacuate and recharge the system.
  • Repair the wiring or connector, or replace the A/C pressure or temperature sensor if it reads incorrectly.
  • Fix any underlying engine cooling fault found, then clear the code and test the A/C.

Can I keep driving?

Medium severity

The car can usually be driven, as the control unit will normally switch off the A/C compressor, but have it checked soon. Leave the A/C off and stop driving if the engine temperature rises abnormally.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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