E1
MrCool High-Pressure Protection / Refrigerant System Overpressure

Indoor unit shows E1 and stops cooling or heating; system may shut down shortly after startup.

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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

Condenser coil blocked or dirty, Outdoor fan motor failure, Overcharged refrigerant, Restricted refrigerant flow in outdoor unit

How to Fix / Troubleshooting

Safety first: Turn off power at the outdoor disconnect and indoor breaker before working near the outdoor unit. High-pressure refrigerant is dangerous.

Steps to try:

  • Clean condenser coil: Remove debris around the outdoor condenser coil. Use a garden hose on low pressure to rinse dirt from the fins (spray from inside out if possible). Do not bend fins.
  • Check outdoor fan operation: Restore power and briefly run the unit. Confirm the outdoor fan motor starts promptly and spins at normal speed. If it hums, stalls, or runs slowly, shut power off and suspect a bad fan motor or capacitor.
  • Verify airflow clearance: Ensure at least 2–3 feet of clearance around the outdoor unit and no obstructions above it.

Technician tasks only: Checking refrigerant charge, restrictions, or a faulty high-pressure switch requires gauges and EPA-certified handling. If cleaning and airflow checks do not clear E1, contact a licensed HVAC technician.

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Repair Difficulty

Hard 4/5

Required Part

Outdoor Fan Motor
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