Heat pumps · Error codes · Joule
90Joule
90 on a Joule heat pump: Compressor locked (repeated error 80)
Short answer
On a Joule heat pump, 90 means: Compressor locked (repeated error 80). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manual says: Compressor locked (repeated error 80).
Is it safe?
On the Modul-AIR exhaust air heat pump
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Installer override required.
On the Victorum exhaust air heat pump
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Safety lockout |
| 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 heating system pressure gauge reading against the value in your handover documents (manufacturer commissioning values: typically 1-2 bar) and that the filling loop is closed.
What the engineer will check
- Manual 'possible solution': Remove error 80.
- Check water flow rate/flow switch and wiring.
- Check strainer/magnetic filter for blockage.
- Vent air from the system.
- Check circulating pump operation and pipe sizing.
- Check valves/zone valves are open.
Who to ask for: heating / plumbing heat pump installer.
Certification: None specific (unvented/G3 if cylinder work).
What you might notice
Sources
- Joule Modul-AIR All-E, Modul-AIR All-E with Green Comfort Module & Modul-AIR Aqua - Installation & Maintenance Manual ENG-0026-07 (UK/IE) ↗ · ENG-0026-07 · page 106 · Reviewed 23 September 2026
- Victorum Pre-Plumb & Victorum Compact Exhaust Air Heat Pump Installation & Maintenance Manual ENG-0014-8 ↗ · ENG-0014-8 · page 97 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026