EC
Keystone Refrigerant System / Low Refrigerant or Sensor Error

Keystone air conditioner shows EC and stops cooling; may restart briefly then shut down again.

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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

Low refrigerant charge due to leak, blocked capillary or expansion device, faulty pressure or temperature sensor, control board misinterpretation

How to Fix / Troubleshooting

Warning: Refrigerant handling must be done by an EPA-certified technician. Do not attempt to open the sealed system yourself.

User-level steps:

  • Clean filters and coils: Ensure airflow is not restricted, which can mimic low refrigerant symptoms.
  • Check for icing: Look for ice on the evaporator coil. If present, allow thawing and then run again. Persistent icing suggests a refrigerant or airflow issue.
  • Observe operation: If the compressor cycles off quickly with EC returning, stop using the unit to prevent damage.
  • Call a professional: A technician should check system pressures, locate leaks, repair, evacuate, and recharge with the correct refrigerant type and weight.
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Repair Difficulty

Professional Required 5/5

Required Part

Sealed Refrigerant System (Compressor / Tubing / Expansion Device)
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