Skip to main content

Enlightening Appliances – AC Window Unit 101

Whether you live in an older house without central air or you’re looking to cool down a hot spot in your home, an AC window unit is an affordable, portable solution to keep the family comfortable in the warmer months.

Here’s all you need to know to find the right unit for you, install it and keep it running just right.


Things to Know Before You Buy

Measure your window: Be sure to measure the window you want to use before buying your AC unit. Window units come in a variety of sizes to suit all types of residences. If there is more than one window in a room, be sure to choose one you’re okay with not opening. 


British Thermal Units (BTUs): BTU numbers range from around 5,000 to 20,000 and indicate how well the unit will cool a space. You can find BTU Calculators online that factors in the size, ceiling height, and type of room, along with how many people are in it at the same time, the insulation condition of the room, the sun exposure and general climate. 

Installing a unit with too high a BTU number will waste energy and using one with too low a number won’t sufficiently cool the space.  


Energy Star: For lower greenhouse emissions and lower monthly electric bills, look for a unit that has the yellow Energy Star label on the box. 


Plug type: Be sure that the electrical outlet you’ll be plugging your AC unit into has the same prongs as the AC unit you’re considering; you don’t want to plug an AC unit into a power cord or extension cord.


Installation & Removal Tips

Safety first: Before you get started on the install, make sure you have a second set of hands to help–a heavy object + an open window can = danger. 


Don’t forget the tilt: While most newer models are designed so that the back of the unit is already at a slight angle from the window/house, some older ones require you to tilt it yourself. This is so that water drips away from the wall. We’re speaking from experience here–an improperly installed AC unit can cause serious water damage!


Follow all the steps in the unit’s directions: If it’s a unit with accordion flaps on either side, take the time to properly screw the edges into the window frame. If the unit arrives with brackets, make sure to use them! Taking the time to properly follow all the steps means a more secure, longer-lasting unit.


Maintenance Tips

Insufficient cooling: Check the filter first. If the filter hasn’t been cleaned or changed in awhile, debris, dust, pet dander and dirt gets caught in the filter, making it impossible for the fan to blow the air through the dirt. 


Weird Smells: Clean the filter and the condenser coil


Dripping Water: This usually means the AC unit is not properly tilted and the water that should be dripping out of the back is dripping straight down the unit itself.


AC Unit Parts

Face Panel: This is the main panel you see on your unit; often you’ll remove this to clean/check/replace the filter.


Evaporator Coil: What cools the air to cool your space


Fan/Blower System: Blows air past the evaporator coil and into the room


Thermostat: Controls the temperature of the air


Compressor: Moves air and coolant through the system/


Condenser Coil: Converts hot air into cool air


Condenser Fan: Blows hot air from condenser coil back outside

DIY + Inspiration

Types of Glue
Types of Toilets
How to Clean Your Gutters
Stay Up To Date With Us
Positive vibes. No mansplaining. Ever. Follow along to learn about the newest Pros on the MBuild roster, our favorite DIY + renovation tips, and stories about badass women in the trades. Let’s build the matriarchy one project at a time.