Low refrigerant charge from a leak; Faulty A/C refrigerant pressure sensor or its wiring or connector; Condenser blocked with debris or cooling fan not working properly; Compressor clutch or compressor failing, giving poor pressure; Restriction in the system, such as a blocked expansion device or orifice, or a moisture-saturated receiver/drier or accumulator; Evaporator temperature sensor fault, or blend/HVAC control fault giving wrong readings; Overcharged or contaminated refrigerant.

P1547

A/C System Performance Degraded.

Cadillac
Powertrain
Manufacturer code
Low severity

How this code is built

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

What it means

On Cadillac models P1547 means the A/C system performance is degraded. The control unit compared what it saw from the A/C pressure or temperature inputs, and sometimes engine conditions, with what it expected while the A/C was requested. The readings showed the system was not cooling or pressurising as it should. The exact monitoring strategy varies by model and year, so check the manufacturer's data for your vehicle.

Symptoms

A/C blows warm or only slightly cool air
A/C compressor clutch not engaging, or cycling on and off rapidly
Weak cooling at idle or in slow traffic
A/C warning message or A/C light flashing on some models
Noise from the compressor or the drive belt area when A/C is on

Possible causes

Low refrigerant charge from a leaklikely
Faulty A/C refrigerant pressure sensor or its wiring or connectorpossible
Condenser blocked with debris or cooling fan not working properlypossible
Compressor clutch or compressor failing, giving poor pressurepossible
Restriction in the system, such as a blocked expansion device or orifice, or a moisture-saturated receiver/drier or accumulatorpossible
Evaporator temperature sensor fault, or blend/HVAC control fault giving wrong readingsrare
Overcharged or contaminated refrigerantrare

How to diagnose

Read all stored codes and freeze frame data to see engine temperature, speed and A/C request status when the code set
Visually inspect the condenser for debris and damage, the drive belt condition, and the A/C pipes and connections for oily residue that suggests a leak
Check the compressor clutch engages when A/C is requested and that the condenser cooling fans run as commanded
Inspect the A/C pressure sensor connector and wiring for corrosion, damage or poor pin tension, and check live sensor data against known good values
Connect manifold gauges and compare static and running pressures with the manufacturer's specification for the model
Check vent outlet temperature against ambient temperature and compare the evaporator temperature sensor reading if available
Leak test the system with an electronic detector or UV dye if pressures are low
If pressures are abnormal but the leak test is clear, check for restrictions by looking at temperature drops across the expansion device and drier or accumulator

How to fix

Repair the leak, replace the faulty component, then evacuate and recharge to the specified refrigerant type and weight
Replace a faulty A/C pressure sensor or repair damaged wiring and connectors
Clean or replace the condenser and repair any cooling fan or relay fault
Replace the compressor or clutch if faulty, and also the drier or accumulator and flush the system where the manufacturer requires it after internal failure
Replace a blocked expansion device or orifice and renew the drier or accumulator, then recharge correctly
Replace a faulty evaporator temperature sensor or correct the HVAC control fault

Can I keep driving?

Low severity

The car can normally be driven as the fault mainly affects cooling comfort and the A/C may be disabled by the control unit. If the compressor is noisy, the belt is squealing or the engine temperature rises, stop and have it checked sooner.

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