Heil air conditioner shuts down on very hot days; diagnostic indicates discharge temperature or compressor overheat fault

Safety first: Disconnect power at the outdoor disconnect before removing panels. Compressor and refrigerant diagnostics should be done by a licensed technician.

• Step 1 – Clean condenser coil: As with high-pressure faults, remove debris and wash the coil from inside out with a garden hose. Allow the unit to dry before restoring power.
• Step 2 – Verify fan operation: Restore power and observe the condenser fan. If it fails to start or is slow/noisy, shut power off and test/replace the fan motor and capacitor.
• Step 3 – Shade and airflow: Ensure the unit is not recirculating its own hot discharge air (e.g., under decks or in corners). Improve airflow or shading if possible.
• Step 4 – Professional diagnosis: If E4 persists after cleaning and verifying fan operation, a technician must check superheat/subcooling, verify charge, and inspect for restrictions or non-condensables.