There are few things more annoying than a breakdown in your air conditioning system in the heart of summer. It also happens that during these times, HVAC contractors' lines are jammed with repair requests, meaning that it could be a while before a technician can get to you.

If you have a good maintenance plan going, a breakdown is often a small matter you can resolve yourself. If not, however, you could be looking at a major fault which can only be fixed by the professionals. Below are some common causes of AC breakdowns, and how to deal with them. For every case, all DIY-fixes will often be described in your owner's manual, so ensure it is kept someplace safe.

1. If rooms take longer to become cool

For your air-conditioning system to work efficiently, there must be unhindered flow of air from the room to the evaporator, where the refrigerant absorbs heat. Usually, there's a filter installed at the return-air vent (warm air from the room to the AC) to keep out dust and other debris.

If you notice your room is unusually warm for your temperature setting, it could mean that the filter is clogged, and hence air isn't being properly absorbed into the AC. Read your manual to find out how to remove and clean the filter before replacing it. You may have to do this more often if you live in a dusty/dry/windy place.

2. If there's water where there shouldn't be

Every time you clean the filter, you should inspect the condensate pan (most models have it under the evaporator) for water. The AC removes both heat and humidity from air, and the water thereof goes into this pan. The pan should channel the water to the bilge, which can get clogged. As a result, water will overflow and go someplace where it can cause more damage. At filter-cleaning time, fill up the condensate pan with water and watch it drain away. If the water seems to go too slowly there's a blockage in the drain system, which can be fixed by simply unblocking the drain.

3. If you think the air conditioner is inefficient

It's important to gauge your AC system's performance by taking the temperatures of air flowing into and out of the AC using a digital thermometer (this is cheap and easily available). Place your AC at the highest speed setting before taking your readings. You should detect difference of 12-20 degrees between them. A lower difference indicates presence of a leakage—even though reverse-cycle AC works in a closed loop, the refrigerant could leak out. However, only licensed AC technicians can check and repair system leaks.