The first step toward getting your HVAC system running properly is to thoroughly read the systems instructional manual. This contains important information provided by the manufacturer that will help you to familiarize yourself better with your specific system.
A/C Unit Does Not Cool
This is the most obvious sign that something is wrong. Start by verifying that your thermostat is set to a couple of degrees below the room temperature. Also, double check that the switch is set to cool. This will ensure that your air conditioner is set to run. It is possible that the reason your system is not running is because of something as simple as a switch bumped to the wrong position. Once you have verified that your settings are correct, if your unit does not start within a few minutes, then shut the power off and determine whether the unit needs cleaning. Remove any debris (leaves, twigs, etc.), and inspect the condenser coils to ensure that they are clean as well. Dirt and debris may be restricting the air flow within your system.
If neither of these steps work, call an HVAC professional to investigate the issue further.
Air conditioning and heating systems rely on clean filters in order to work properly. These filters are designed to remove dust and allergens from incoming air so that your home contains clean, fresh air that is safe for the whole family to breathe. Unfortunately, many people don't changing out these dirty filters regularly. Filters that have been in use for several months will be ineffective in trapping new dirt. Further, unclean filters force your unit to work extra hard in order to continue pumping air into your home. Over an extended period of time this extra stress can cause your unit to stop working. Filters are inexpensive so be sure to change them every few months.
Many modern heating systems are constructed from metal materials which are conducive to high noise volumes. If the noise level of your system bothers you, you may consider calling a professional contractor to install insulation between your heating and cooling system as well as around the air ducts. Another possible solution, and this relates to popping sounds you may be hearing, is to use a hammer to make a small dent along the air duct from which you hear the noise. This will prevent the metal from moving while the system is operating.