Heat pumps · Error codes · Joule
35Joule · Modul-AIR exhaust air heat pump
35 on a Joule Modul-AIR exhaust air heat pump: Airflow sensor error - Green Comfort Module
Short answer
On a Joule heat pump, 35 means: Airflow sensor error - Green Comfort Module. 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: Airflow sensor error - Green Comfort Module.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Manual reset: Installer override required.
What you can check
- Read and note the code shown on the controller display, then contact your installer or service engineer.
What the engineer will check
- Manual 'possible solution': Check sensor. Replace if necessary.
- Check the named sensor/probe connection at the PCB (loose/oxidised plug).
- Measure sensor resistance against the manufacturer table and replace if faulty.
- Check controller/PCB if sensor is good.
Who to ask for: heat pump controls / electrical.
Certification: Electrical competence.
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 105 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026