Lennox Evaporator Coil Freeze-Up

Lennox air conditioner frequently freezes the indoor coil; ice forms on refrigerant lines and coil housing.

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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

Dirty air filter, Closed or blocked supply/return vents, Low blower speed, Low refrigerant charge or TXV issue

How to Fix / Troubleshooting

Safety: Turn off cooling and set fan to ON to thaw the coil. Do not chip ice.

  • 1. Replace filter and open vents: Ensure unrestricted airflow through the Lennox air handler.
  • 2. Inspect coil after thawing: Clean any dirt or debris from the coil surface.
  • 3. Verify blower speed settings: On PSC systems, confirm the cooling speed tap is on the correct terminal. On ECM systems, a technician can adjust airflow settings.
  • 4. Schedule refrigerant check: If freeze-ups continue, a technician must check for low charge or TXV malfunction.

Note: Repeated freeze-ups can cause water damage and compressor stress.

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Repair Difficulty

Medium 3/5

Required Part

Lennox TXV (Thermostatic Expansion Valve)
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