It may be difficult to locate in some air conditioning systems, but you can usually find the air filter in the return air duct. Or in simple terms, that big metal grille on the wall, floor, ceiling, or utility closet door. Return air ducts can be almost anywhere. Sometimes, especially with older systems, the filter is located inside the oven itself, next to the fan motor.
And some systems have a central filter grille installed on the wall or ceiling. The grille opens and reveals the air filter. The air filter is usually close to your home thermostat, in a return duct. Or, it's most likely right next to your air conditioning system's air controller.
Some larger homes have more than one climate control system and each of them will have at least one filter. First, look for filters inside or near the HVAC unit itself. Most likely, these filters are located next to the oven or air conditioning controller. The HVAC unit is often located in an attic, basement, or in the back of a closet (somewhere out of the way).
Once you've found the unit, look for a removable or hinged cover approximately one inch wide. It can be oriented horizontally or vertically, and you should find a filter that is already in place. Many air conditioning systems or hot air handlers, both horizontal and vertical, have one or more air filters that are installed within the fan assembly itself. With the HVAC system operating efficiently and without having to force air through clogged filters, you can save money on your monthly heating and air conditioning bills.
The air filter may be in one or more common air returns or in the air controller, or less commonly, in a slot in the return air duct near the air controller. You may see household dust deposits around the edges of the opening where the air filter is mounted, indicating where the air shunt leaks. We'll replace your air conditioner's air filter, clean the ducts, fix any other air conditioning problems you have, and answer all your questions. In this photo of a slot intended to receive an air conditioning filter in the ventilation unit, the filter had simply been left out and the slot had been left open, drawing dirt, dirt, moisture and mold from nearby basement areas.
Start by looking for a waste source near the central air return system; continue to look for leaks that could attract debris to the return air duct system anywhere along its length. Vertical air handlers can be an upflow unit that has return air that enters through the bottom of the air handler or blower and air conditioner (cooled or heated) that exits the upper part of the unit. If the system has been operating in heating mode, the air supply or outlet ends of the ducts connected to the air controller will be hot to the touch and the intake or return air ducts will be cooler. Someone may have added this air intake (yellow arrows) to improve the total air flow through the system, but extracting the return air that is located near the oil or gas burner of a furnace may do so.
There should have been a metal divider that prevents significant air intake if you only use a 1-inch filter. They have a larger surface area than other filters and can work effectively for approximately 3 months to a year before being replaced. I like a filter on the air intakes because it helps keep the return ducts and the fan fan clean; however, if you already have a suitable air filter in or on the air controller that should protect the fan, you would be careful to add more layers of filtration without talking to your HVAC company about the air the flow rate requirements of your system and the restriction of additional filters to ensure that you are not slowing down the air supply through the system. It is usually found in the return air duct or in the fan compartment before the return air reaches the air controller.
In almost all central air cooling or heating systems, the fan is located at the return air end of the system. .