Heat pumps · Error codes · Cool Energy
AL037Cool Energy · inverTech (R410A, Carel control)
AL037 on a Cool Energy inverTech: BLDC-alarm:Out of Envelope
Short answer
On a Cool Energy heat pump, AL037 means: BLDC-alarm:Out of Envelope. 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: BLDC-alarm:Out of Envelope.
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 heat pump's breaker/isolator at the consumer unit is switched on (do not repeatedly reset if it trips).
What the engineer will check
- Check inverter drive (Carel Power+ / driver board) alarm log and parameters.
- Check supply voltage, DC bus, earth faults and drive cooling.
- Check compressor wiring/phase sequence and drive-to-controller communication.
Who to ask for: heat pump electrical / inverter.
Certification: Electrical competence (Part P / qualified electrician).
What you might notice
Sources
- Cool Energy inverTech Monoblock Series Heat Pump Water Heaters - Installation and Users Guide v6.6 (2020) ↗ · Version 6.6 · page 29 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026