Air conditioning systems are regulated appliances, requiring expert sizing and maintenance to function most efficiently with the lowest energy consumption.
Who installed your unit? and when was it last serviced?
There are many persons out there who goes out and "learns a trade" then go on to work for either themselves or others as air conditioning technicians. If you ask them what their training program was, the answer will more than likely be "I learnt on the job". This is not necessarily a bad thing but it does also mean that the technician will not really understand the intricacies or finer details of every situation. They will make assumptions about certain things and create other problems which will usually cost you more than it should.
Is my unit the right for my site?
Questions like these are questions we get all the time and the fact is, many people purchase based on price, so sometimes a technician will recommend a smaller unit because its cheaper, not necessarily because its adequate.