Er37 on an Ochsner OTE 3 / OTE 4 controller fault platform: Low pressure. Cause/remedy per manual: Insufficient heat source energy, insufficient refrigerant, expansion valve Check refrigerant circuit Contact OCHSNER Customer Service
Short answer
On an Ochsner heat pump, Er37 means: Low pressure. Cause/remedy per manual: Insufficient heat source energy, insufficient refrigerant, expansion valve Check refrigerant circuit Contact OCHSNER Customer Service. 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: Low pressure. Cause/remedy per manual: Insufficient heat source energy, insufficient refrigerant, expansion valve Check refrigerant circuit Contact OCHSNER Customer Service.
Part involved: Low pressure.
Likely causes:
- Insufficient heat source energy.
- insufficient refrigerant.
- expansion valve.
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.
Resetting itself: Heat pump restarts automatically when the safety assembly re-enables it; 2 automatic acknowledgements allowed (manual 17.2).
Manual reset: Up to 3 manual acknowledgements via ESC > ERROR menu > setting button (manual 17.2.1).
What you can check
- Note the Er number and text (ESC on main screen opens the alarm menu) and contact your OCHSNER system partner.
- The manual allows the user to try acknowledging an ERROR once via the ESC menu; if it returns, leave it and call the installer.
What the engineer will check
- Check refrigerant circuit.
- Contact OCHSNER Customer Service.
Who to ask for: OCHSNER customer service / authorised service partner (manual: ERROR faults only remedied by OCHSNER or authorised partners).
Certification: F-gas certification for refrigerant circuit work.
What you might notice
Sources
- OCHSNER OTE 3 / OTE 4 Controller manual (end customer), EN06 ↗ · EN06 (RA_982072) · page 52 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026