Start with electricity
Check the distribution board and the isolator near the unit. If the breaker has tripped, reset it once. If it trips again, leave it off and call — repeated resets on an earth fault are unsafe.
Then check the controller
Note the displayed water temperature, the set-point and any error code. A unit set to 45°C is not faulty for delivering 45°C water, and a timer restricting run hours explains many complaints.
Then look and listen
Is the fan turning? Is there ice on the coil? Is there water under the unit? Is there a new noise? These four observations narrow the diagnosis substantially before a technician arrives.
What to have ready when calling
Brand and approximate age, the error code if any, when the problem started, and whether anything else changed — new plumbing work, a power outage, or a change in occupancy.
If you want this assessed on your own property, call 069 268 0988. We inspect, explain what we find, and quote in writing.