My aircon unit failed a couple years ago. I have procrastinated long enough.
This morning I decided to pull it out of the window housing, and determine if it was worth fixing, or replacing with a new unit. It is around 20 years old.
Replacement cost is around 500/600 dollars.
On inspection, the air fan had dry seized bearings, and had blown an internal fuse.
A spray and soak the bearings with WD40 performed a miracle, and I replaced the fuse.
Thermostat was suspect as well, but that was just the contacts jammed up with dust and cat hair.
Unit is now in running order, and I have the heat on again.
(should have done it ages ago... would have saved the massive winter power bill, as it's heaps cheaper to run than the 'lekky heaters.)
I guess I really needed this recent cold weather burst to force me to have a look at the unit.

Total cost, an hour and a half of my time, a squirt or two of WD40, and one glass tube fuse from my 'bitza' box