System Diagnosis
Actuation of low pressure switch (LPS)
Daikin Packaged
Error Code E4
Troubleshooting guide for the Daikin Packaged system fault E4.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
Potential Causes & Solutions
- Abnormally drop in low pressure.
- Defective low pressure sensor.
- Defective outdoor unit PCB.
- Defective connector contact.
Verify Before Replacing Parts
- Confirm the exact Daikin model family and packaged context before acting on a generic code description.
- Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem.
- After the correction, run the system long enough to confirm the code does not return under normal load.
Field Signals to Confirm
What usually confirms it
Pressure and temperature readings that stay out of range after airflow is verified.
What can fool you
Dirty coils or airflow restrictions can look like a charge problem until the air side is cleaned up.
When to Escalate the Call
- You suspect a restriction, leak, or compressor issue that needs deeper system evaluation.
- The readings do not normalize after airflow and coil conditions are corrected.
Still unsure about this fault?
ACLogics walks you through Daikin Packaged diagnostics step-by-step — so you confirm the cause before swapping parts.
