E035 on a CTC control system alarm/information platform: High pressure switch: the refrigerant high-pressure switch has tripped
Short answer
On a CTC heat pump, E035 means: High pressure switch: the refrigerant high-pressure switch has tripped. 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: High pressure switch: the refrigerant high-pressure switch has tripped.
Part involved: high pressure switch.
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
- If the manual instruction applies, press "Reset alarm" on the display once and note whether the alarm returns (manual: "Press reset and check whether the alarm recurs. If the fault recurs, contact your installer").
- Note the alarm code/text, the product model and serial number and contact your installer.
- Check the outdoor unit (air source) is not blocked by snow, leaves or debris.
What the engineer will check
- Check refrigerant circuit pressures and temperatures with gauges.
- Check expansion valve, sensors and compressor operation.
- Check heating-side flow (charge pump, filters) and brine/air side flow.
Who to ask for: refrigeration / heat pump.
Certification: F-gas certification (refrigerant circuit work); R290 units require flammable-refrigerant competence.
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 80 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026