Fujitsu Waterstage A3 fault code
Fujitsu Waterstage heat pumps
What the Fujitsu Waterstage A3 fault code means, from the manufacturer's own service literature, and the UK models it applies to.
What it means
Compressor temperature protection (permanent stoppage)
Source: Fujitsu Waterstage Comfort D&T Manual DA_CF001EF, §Control System pp.03-2…03-4 (official-distributor mirrors) — numeric display codes with Fujitsu's own reset and runs-despite-error columns, plus the interface-card LED table
UK models this code applies to
Tap yours to open A3 on that machine.
A3 on these comes from each model's own manual, which may not match the meaning above — tap yours to read it.
Now the harder half: proving what caused it
A3 names a symptom, not a root cause. In the app, the same code opens a guided investigation: what to measure first, the expected values for your exact model, and an honest verdict — including “nothing in this machine is broken” when that's what the readings say.
Chase A3 on your machine →Free, no sign-up. We don't hold a chart for this code yet — pick the model for its manual section.
Or watch one get chased — free demo →
Or use it in your browser on any phone or laptop.