Low refrigerant charge from a slow leak; Faulty A/C refrigerant pressure sensor or its wiring and connector; Compressor clutch not engaging or worn (clutch gap, coil, relay or fuse); Condenser blocked with debris or condenser cooling fan not working properly; Restricted expansion valve or orifice tube, or blocked system; Internal compressor wear or failed compressor control valve; Faulty evaporator temperature sensor or climate control module fault.

P1547

A/C System Performance Degraded.

Chevrolet
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

P1547 on a Chevrolet means the control unit has judged that the air conditioning system is not performing as expected. It typically sets when refrigerant pressure, evaporator temperature or compressor operation readings do not match what the system should achieve with the A/C requested. The exact monitoring strategy and sensors used vary by model and year.

Symptoms

A/C blows warm or only slightly cool air
A/C cools poorly at idle but better when driving, or the reverse
Compressor clutch cycles rapidly or does not engage
Air conditioning warning or fault message on the dash on some models
Engine idle dips or surges when the A/C is switched on

Possible causes

Low refrigerant charge from a slow leaklikely
Faulty A/C refrigerant pressure sensor or its wiring and connectorlikely
Compressor clutch not engaging or worn (clutch gap, coil, relay or fuse)possible
Condenser blocked with debris or condenser cooling fan not working properlypossible
Restricted expansion valve or orifice tube, or blocked systempossible
Internal compressor wear or failed compressor control valverare
Faulty evaporator temperature sensor or climate control module faultrare

How to diagnose

Read all stored codes and freeze frame data, noting ambient temperature, engine speed and A/C request status at the time it set
Check the A/C feels cold at the vents and see whether the compressor clutch engages and stays engaged
Inspect the condenser for debris and damage, and confirm the cooling fans run when the A/C is on
Check the A/C fuses and relay, and inspect the pressure sensor and compressor wiring and connectors for damage or corrosion
Look for signs of refrigerant leaks such as oily residue on pipes, joints and the compressor, and use a leak detection method
Connect a manifold gauge set and compare static and running pressures against the manufacturer specification for your model
Use a scan tool to compare the pressure sensor reading with the gauge reading and check the live A/C data
Check for blockages by looking for temperature drops across the expansion valve or orifice tube, following model-specific procedures

How to fix

Find and repair the leak, then evacuate and recharge the system with the correct refrigerant type and quantity
Replace a faulty pressure sensor or repair damaged wiring and connectors
Replace the failed relay, fuse or compressor clutch components, or the compressor if it is worn
Clean or replace the condenser and repair the cooling fan fault
Replace the restricted expansion valve or orifice tube, along with the receiver-drier or accumulator, and flush the system as the manufacturer specifies

Can I keep driving?

Low severity

The car is safe to keep driving, as this is a comfort system fault. Book it in soon, as running with low refrigerant or a failing compressor can lead to a more costly repair.

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