72 on a Mitsubishi Heavy Industries Air-Conditioning Europe Hydrolution HM gen 1: Low pressure below 0.65 MPa in cooling mode (auto reset above 0.83 MPa or condenser out above 14 C)
Short answer
On a Mitsubishi Heavy Industries Air-Conditioning Europe heat pump, 72 means: Low pressure below 0.65 MPa in cooling mode (auto reset above 0.83 MPa or condenser out above 14 C). 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 below 0.65 MPa in cooling mode (auto reset above 0.83 MPa or condenser out above 14 C).
Part involved: Anti freeze HX.
When it shows: Low pressure below 0.65 MPa in cooling mode (auto reset above 0.83 MPa or condenser out above 14 C).
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes.
Manual reset: no.
What you can check
- Note the alarm number/text shown on the display. Check the consumer-unit breakers/isolators for the indoor and outdoor units are on. No action needed if it clears; if it keeps recurring, contact the installer.
What the engineer will check
- Review flow rate, set temperatures and defrost conditions; if escalated see alarms 5/6/7/14/16.
Who to ask for: Heat pump / refrigeration engineer (manufacturer-trained).
Certification: F-gas certification for refrigerant-circuit work; electrical competence (Part P/18th Edition) for PCB/wiring.
What you might notice
Sources
- Technical Manual HM-T-193 - Air to Water Heat Pump (Hydrolution) ↗ · '13 HM-T-193 (updated December 18, 2014) · page ML p.155 (printed 154) - 'Alarm with automatic reset' · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026