E18
Ariston Condensate Pump / Drain Pump Fault (for cassette or ducted models)

Unit shows E18; may shut down unexpectedly during operation.

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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

Blocked condensate drain line, Failed internal drain pump, Faulty float switch, Loose pump wiring

How to Fix / Troubleshooting

Safety first: Turn off power before working on the indoor unit. Water may spill when opening panels.

  • Step 1 – Check drain line: Locate the condensate drain hose from the indoor unit. Ensure it is not kinked, elevated too high, or blocked. Clear any visible blockage.
  • Step 2 – Clean drain pan: Remove the indoor access panel and inspect the drain pan. Remove sludge, algae, or debris and clean with mild detergent.
  • Step 3 – Test float switch: Locate the float switch near the pump. Gently move it up and down; it should move freely. Clean if stuck.
  • Step 4 – Listen for pump operation: Restore power and run the unit. When water accumulates, you should hear the pump run. If not, check the pump wiring connector.
  • Step 5 – Replace pump or float: If the pump does not run or the float switch is defective, replace the condensate pump assembly or float switch with Ariston-compatible parts.
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Repair Difficulty

Hard 4/5

Required Part

Condensate Drain Pump
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