E163 on a CTC control system alarm/information platform: Defrost max time duration: defrost did not complete within the maximum time; make sure evaporator ice has gone
Short answer
On a CTC heat pump, E163 means: Defrost max time duration: defrost did not complete within the maximum time; make sure evaporator ice has gone. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Defrost max time duration: defrost did not complete within the maximum time; make sure evaporator ice has gone.
Part involved: outdoor coil defrost.
Likely causes:
- Defrost not completed within maximum time.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Manual reset: Press "Reset alarm" on the display; a persisting fault must be rectified before it can be reset.
What you can check
- Check the outdoor unit is not blocked by snow or ice build-up around it (do not chip ice from the coil).
- Note the alarm code/text, the product model and serial number and contact your installer.
What the engineer will check
- Check defrost operation, 4-way valve, sensors and heating-side return temperature during defrost.
Who to ask for: refrigeration / heat pump.
What you might notice
Sources
- CTC EcoZenith i255 Installation and Maintenance Manual (400V 3N~/230V 1N~/230V 3~) ↗ · 162 505 67-9 CR01164 2026-05-10 · page 81 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026