Changing your filters once a month keeps a system healthy and lowers operating costs. Look for dirt and hair in a filter to see how often you might need to change yours. The best filters to get are ones that are “MERV 5 to 8” rated.
One inch filters should be changed once a month or more during the summer, here in Texas, they typically don’t make it 3 months.
Four inch filters under normal conditions should last 6 to 12 months.
We do not recommend duct cleaning in general. Here is why: Most modern duct work is flex or duct board. The steam or cleaning solutions typically used will loosen the material the duct work is made of and the brush will tear it apart. The only duct work that is safe for cleaning is metal duct, but still the air conditioning equipment is lined with insulation and that will be degraded. If your duct work is dirty, that is an indication that something else is wrong and a repair is needed, not cleaning.
Every air conditioner has a drain line to collect and direct water away from the unit. Usually the drains lead to the outside or under a sink in a bathroom. To prevent clogs, we suggest that one-half of a cup of bleach and one half cup water (hot preferred) be poured into the breather pipe to help keep this line clear. Also yearly scheduled maintenance helps keep the drain clear and prevent backup which leads to water leaks. But there are devices for preventing that, too. A float switch will turn off a unit if the drain pan or drain line becomes too full and isn’t draining.