There are few things as frustrating as a malfunctioning HVAC system. If your HVAC system has suddenly stopped cooling, you may be tempted to troubleshoot it on your own. Though you probably don't want to do any extensive work on your own, here's a few things you can check.
1. Wash the Condenser
The condenser for an HVAC unit is usually going to be positioned outside of your home. It has to be regularly cleaned in order to continue functioning well -- dust, debris, and dirt can all become captured within its tines. Turn off your HVAC system and use a hose to clean the exterior of the condenser thoroughly. If the tines have become dented or damaged, you can use a special condenser comb to straighten them out.
2. Clean the Evaporator
An HVAC system has evaporator coils at the very top of the unit. In order to find yours, you should consult your manual. Evaporator coils occasionally need to be cleaned off, or dust can also make them ineffective. To clean them, cut power to your HVAC system and then spray the evaporator coils with evaporator coil foam. This foam does not need to be rinsed off: it will turn into liquid and drip off into the drip pan on its own. Once you've covered the entire surface of the coil in foam, you can close up the unit again and turn it back on.
3. Clear the Filter
Many HVAC systems today have multiple filters. One filter may be at the air intake, while another filter may be at the base of the machine itself. Check to make sure that both filters have been recently cleaned. Most HVAC systems have to have their filters replaced every three to six months -- if you live in an area with a lot of dirt (or if you have pets), you may need to change them more frequently than average.
If none of that works, it's time to call a professional air conditioning repair service. AC systems tend to be fairly complex, and gas-powered AC systems especially can be dangerous to work on. A professional may need to recharge your coolant or may need to fix a leak in your duct work. Either way, calling a professional will likely save you both time and money -- and most companies will be able to offer an estimate before you commit to work.