Check the mode
If you think your air conditioning unit isn't working to its optimum capacity, then make sure it is in the correct mode. It may be that we have just come into summer and you're wanting to stay cool but your unit is still set to 'heating' mode.
Change the batteries
If you can't get your unit to turn on/off but the remote still has a display, the batteries could be failing. Try changing the batteries for new ones to see if this helps.
Turn it off and on again!
That age-old piece of advice that people roll their eyes at... sometimes it actually works! Electrical faults and errors can occur for many reasons but, in our area especially, the cause could be an electrical surge or drop. A power variation could cause your unit to fault and the lights will start flashing. Try switching your unit off at the circuit breaker and leaving it off for 20 minutes; this should clear any electrical faults or errors in the unit. This doesn't always work but it's worth a try. If it works but the fault keeps reoccurring, the unit will need to be serviced.
Clean your filters
It is very important to clean your filters regularly. If you don't, it will adversely affect your unit's performance. Blocked filters can eventually cause leaks or even damage the compressor. Cleaning your filters regularly will increase the longevity of your unit.
Clear the drain
The drain outside needs to be kept clear of debris. Weeds and dirt can block the drain and the outcome is that the water will drain out of the unit the other way, down the wall from the indoor unit.
Make sure the outdoor unit is kept clear and does not have anything around it that would restrict the airflow - this includes anything covering the unit, as well as weeds or shrubs around it. Your unit will not perform to its optimum capacity if it does not have proper airflow. Even building a new fence closer to the outdoor unit can cause an issue.