E4
Day & Night
High-Pressure Protection / Discharge Overheat
E4 displayed, compressor stops, unit may run fan only
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
Dirty or blocked outdoor condenser coil, Failed or non-running outdoor fan motor, Overcharged refrigerant system, Blocked or closed liquid line service valve, Faulty high-pressure switch or discharge temperature sensor
How to Fix / Troubleshooting
Safety first: Turn OFF power at the outdoor disconnect. Do not attempt to open the refrigerant circuit; only EPA-certified technicians may handle refrigerant.
- Step 1 – Clean the condenser coil: Remove debris from around the Day & Night outdoor unit. Take off the top grille if needed and gently hose the coil from inside out with low-pressure water. Avoid bending fins.
- Step 2 – Check outdoor fan operation: Restore power and briefly run the unit. Confirm the outdoor fan starts immediately and spins at normal speed. If the fan does not run or is slow, shut power OFF and inspect the fan motor and capacitor.
- Step 3 – Verify airflow clearance: Ensure at least 18–24 inches of clearance around the unit and no obstructions above it.
- Step 4 – Inspect high-pressure switch wiring: With power OFF, locate the high-pressure switch on the liquid line or compressor discharge line. Confirm its wires are intact and firmly connected to the control circuit.
- When to call a pro: If E4 recurs after cleaning and verifying fan operation, a technician must check refrigerant charge, high-pressure switch function, and system design pressures.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Outdoor Fan Motor
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements