Heat pumps · Error codes · Cool Energy
Er66Cool Energy · ecoTech DC Inverter (R32 EVI)
Er66 on a Cool Energy ecoTech DC Inverter: DC fan 2 fault
Short answer
On a Cool Energy heat pump, Er66 means: DC fan 2 fault. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: DC fan 2 fault.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
What you can check
- Read and note the code shown on the controller display, then contact your installer or service engineer.
- Check the outdoor unit/air grilles are not blocked by debris, leaves or snow.
What the engineer will check
- Check fan motor, wiring and PWM signal.
- Check fan blade for obstruction or ice.
Who to ask for: heat pump engineer.
Certification: Electrical competence.
What you might notice
Sources
- Cool Energy ecoTech Monoblock Series R32 EVI Heat Pump Water Heaters - Installation and Users Guide v2.1 (2022) ↗ · Version 2.1 · page 31 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026