E15
Rheem
Compressor Safety Lockout Indication
Thermostat displays E15 and may indicate 'Compressor lockout active' or 'High/low pressure lockout'.
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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.
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Possible Causes
High-pressure or low-pressure switch open at outdoor unit, Locked rotor or overloaded compressor, Outdoor fan failure causing high head pressure, Faulty pressure switch circuit
How to Fix / Troubleshooting
Safety first: Compressor and high-pressure circuits are hazardous. Many checks should be done by a licensed HVAC technician.
Homeowner-level checks:
- Inspect outdoor unit: Ensure the condenser fan is running when cooling is called. If the fan is not running but the compressor hums or E15 appears, shut the system off and call a technician.
- Check airflow: Make sure the outdoor coil is not blocked by debris, leaves, or covers. Clean gently with a garden hose (power off first).
- Power cycle: Turn off the system at the thermostat and breakers for 5–10 minutes, then restore power to reset lockouts.
- If E15 returns quickly: A pressure switch or compressor problem exists. Do not continue to run the system; contact a professional to test pressures, switches, and compressor health.
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Repair Difficulty
Professional Required
5/5
Required Part
Compressor Protection Circuit (Pressure Switches)
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