An HVAC contractor can do things that only trained professionals can do like inspect the electrical connections, lubricate moving parts, check the refrigerant, and test the controls of the system to make sure everything is operating smoothly.
You might have to maintain the filter more often if you live with furry pets or if you use your AC in really dusty conditions. Note that this applies to both central AC units and window-mounted air conditioners.
In central AC units, the filters are usually located somewhere along the length of the return duct behind a grill in the wall or ceiling. In window-mounted AC units, the filters are behind the grill that faces into the room.
If you have a ductless split AC unit, you can just wipe off the filter behind the panel with a damp rag.
Replacement filters only cost about $10 USD or so. There are usually arrows on the filter showing you which way to orient it when you put it in your air conditioner.
On central AC units, the access panel for the coils is on one side of the outdoor condenser unit. For window-mounted AC units, the coils are located behind a panel on the back of the unit that faces outside. You only have to do this once a year to keep your AC unit’s coils clean. A good time to do so would be at the beginning of the summer if you live in a seasonal zone. AC coils are the parts of the system where the refrigerant absorbs heat.
You can buy a special brush called a coil brush to do this, or just use any kind of whisk brush with soft nylon bristles. They’re pretty much the same thing. Note that this applies to any type of air conditioner.
If your condenser unit is located in your yard, avoid passing a lawnmower right by the unit because it could shoot grass and other debris into it. You can use a pair of garden shears to keep grass right by the unit trimmed. This applies to central AC system condenser units, since window-mounted air conditioners aren’t on the ground. Condenser units are the outdoor part of the HVAC system that release or collect heat.
You can get a fin comb from AC wholesalers or online. If the coil fins are bent, they can block airflow through the coils and hurt performance. This applies to both central and window-mounted AC units.
Note that this only applies to central AC units. Window-mounted units don’t have condensate drain lines. Condensate drain lines let all the moisture that gathers in the system drain out. They are usually white pipes that run out of the outdoor condenser unit.
One way to seal gaps around a window-mounted AC unit is by sticking adhesive-backed weather stripping around the unit. You can also fill small gaps by pressing rope caulk into them. Rope caulk is a clay-like material, so just mold it to fit into the cracks. If the seal is not good, cool air from the AC unit can escape your home through the crack.
This is also a good time to rinse any water out of the condensate pan beneath the coils with fresh water from your hose.
This helps your window-mounted AC unit last much longer than if you let it weather the winter in your window sill.
Outdoor condenser units are pretty durable and meant to hold up to cold weather, but excessive snow and ice can still damage the coils over time. Avoid hard plastic covers or any type of covers that completely restrict airflow because they can trap excessive moisture inside the unit, leading to internal damage.
