ALRM002 on a Trianco Activair Indoor R32 5/7kW: Low-pressure switch tripped
Short answer
On a Trianco heat pump, ALRM002 means: Low-pressure switch tripped. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Low-pressure switch tripped.
Part involved: pressure switch / compressor discharge-suction.
When it shows: Open pressure switch MI2 contact.
Likely causes:
- Insufficient refrigerant charge.
- Excessive amount of antifreeze.
- Insufficient air flow to air cooler.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
Resetting itself: Generally automatic when the activation condition clears (conditions must persist e.g. 30 s).
Manual reset: If the alarm trips repeatedly (e.g. 3 times in 1 hour) it must be reset manually by the Technical Assistance Centre (press and hold the reset key until padlock and alarm symbol clear).
What you can check
- Note the exact code shown on the controller (a photo helps) and report it to your installer or the manufacturer's service line.
- Check the heat pump's supply breaker/isolator at the consumer unit is on (do not open any casing).
- Check the outdoor unit is not blocked by debris/snow and has its required clearances.
What the engineer will check
- Check for: Insufficient refrigerant charge.
- Check for: Excessive amount of antifreeze.
- Check for: Insufficient air flow to air cooler.
Who to ask for: refrigeration.
Certification: F-gas certified refrigeration engineer (REFCOM or equivalent).
What you might notice
Sources
- Trianco Activair Indoor Air Source Heat Pump 5 & 7kW - Control Panel Operation Manual ↗ · 2024-11 · page 41-42 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026