Our central air conditioner unit is over 12 years old and recently it has been working quite as reliably as we’d like. About once every couple of days now it simply “stops” coming on and I have to try a bunch of different things to get my air conditioner working again.

Linkback: https://www.plumbers.nz/central-heating-and-underfloor-heating/8/central-air-conditioner-not-working/996/

1. First feel the air coming out of the unit. You should feel heat being removed from the house.
2. Next look at the 2 freon lines - there will be a big one and a little one. The little one may be very hot so be careful. The big one is the low pressure side and on normal conditions where the pipe is exposed should be cold a sweaty.
From this big line you can tell alot.(you will have to find a place where the insulation is off or right where it goes into the outside unit)
3. If it is frosted up then go to 4 if not go to 5.
4. This could be due to either insufficient air flow across the coils of the inside unit or low freon which will cause the coil to start freezing.
If there is frost, cut the unit off at the thermostat by switching the heat/cool switch to off and turn the fan switch from auto to on. This will cause the fan to continue running and turn off the compressor outside. Leave it this way for a minimum of 30 minutes. See if you notice the air flow to improve coming out of the vents. While it is off you can check your air filters and make sure they are clean. Replace if necessary. Later turn the A/C thermostat back to cool. Notice if it cools better and monitor the big line. If after about five minutes the line is cool to cold then the freon level may be OK and you should feel hot air coming out of the unit. If it is only barely cool or not cool the unit is probably low on freon.
5. If the big line is not cool and the little line is not warm then either you are very low on freon or your compressor isn't running. Either way you will need to contact me for making your system up and working again i have done little bit search for you and you can contact these people.
Hope i offered some help
Myles