Two office floors, twenty two split units, and a complaint that the building was never cool after two in the afternoon.
Nothing was broken. Nineteen of the twenty two outdoor coils had a salt crust thick enough to stop them rejecting heat, because the previous arrangement had been an annual visit that washed the indoor filters and nothing else. Two units were low on gas from leaks that had been topped up twice. One had a fan motor running on a dry bearing and about a month from seizing.
We washed every coil properly over two evenings, found and repaired both leaks, recharged both by weight, and replaced the fan motor. Then we put the floors on a contract with four visits a year written into the diary rather than requested, and moved the visit weeks so that two of them fall before the hottest months rather than after.
The firm's own figure was a twenty one per cent fall in the electricity they were paying for the floor over the following four months. We did not promise that and we would not promise it to anybody else, but a coil that cannot reject heat makes a compressor work for nothing and the arithmetic is not mysterious.