Installing a Window AC Unit: The Comprehensive Guide

By Laura Parker
July 13, 2023

This is a Task for a Professional

As a professional handyman, it is part of your job to perform successful window AC installations. You do it all the time, so it is important to streamline your efforts and work effectively and efficiently. All the while, being a true professional means doing a great job and providing excellent customer service–after all, you certainly want to get called back for future jobs from the same customer.


The only way to keep growing your customer ratings is to do a great job, but don’t worry, we have compiled everything you need to make sure that your installation goes smoothly.


What Tools Will You Need?

The most important part of the job is to always make sure you have the essential tools. To install a window AC unit, you are going to need these tools and materials:

  • Drill
  • Screwdriver
  • Level
  • Vacuum 
  • Insulating foam strips


Step-by-Step Installation Guide

We know that you have done quite a few installations in your time as a professional but here is one of the most effective strategies to go about a window AC installation.


  1. Open the bottom sash of the window as far as it can go and remove the window screen if there is one. Make sure to provide extra care by using a vacuum to clean the sill and channels.
  2. Before putting the AC unit on the windowsill, find the wall socket and make sure that the extension cord can reach it from the window. The AC unit will usually come with accordion or sliding extensions to create a better fit with the window. You’ll need to prepare these beforehand.
  3. You’ll need to see if the AC unit utilizes mounting brackets or simply sits on the windowsill. If mounting brackets are provided, follow the manufacturing instructions carefully. Use a level to make sure that you install it in the recommended way–usually manufacturers suggest that the unit be installed with a slight downward slope to the outside to allow for condensation drainage.
  4. Now that everything is prepared properly, lift the AC unit and slide it into the window opening from the inside. Either sit the AC unit on the sill or position it on the supporting brackets. Important–make sure that you do this carefully so that the AC unit does not fall out the window!
  5. Lower the window sash so it fits nicely on top of the AC unit. Slide the accordion or sliding extensions to fill any remaining gaps in the window and fasten them with a jamb.
  6. Seal the inside perimeter with insulating foam strips (this could be provided by the manufacturer). Caulk around the outside perimeter for an excellent installation.
  7. Plug in the AC unit and you’re all set!

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How to Clean Window AC Units

Another common job you may be asked to do is to clean an existing AC unit. Or you may be asked after installing a new unit how the customer can properly take care of the AC unit. Don’t worry, we have you covered. We recommend a thorough cleaning of your AC unit at least once a year. In general, the main thing to do is properly care for the filter screen.


To access the filter of an AC unit, you just need to pop open the front grill with a putty knife and pull out the mesh filter. For best results, wash the filter and the grill in warm, soapy water. Watch out for mold! If there is any, use bleach to get rid of it.


In addition, you should vacuum the evaporator coils underneath the filter as well as the condenser coils in the back of the AC unit. This process makes sure that you rid your unit of any possible extraneous debris that could be getting in the way of your cool air.


Making it Fast and Easy

When you are experienced with window AC installations, working fast is fine, but make sure that you do not sacrifice safety in the process. An improperly attached unit could fall out the window, causing damages and danger to those around. Another common mistake is failing to make sure that the window fits the specifications for proper installation. Your customer may believe that it works, but it is up to you as a professional to make your own judgement on whether the installation is possible.


Make sure you take care of the AC unit you are installing. No customer likes to see someone damage their brand-new equipment, and you may have to pay for damages if you do so. 


Providing Great Customer Service

Part of your job as a professional installer is to provide great customer service no matter what. You’ll want to retain your customer ratings which means that you want your customers to be happy when you have finished your installation. Be sure to listen to the requests of your customer and do your best to adhere to them. Be congenial and engage in conversation as you go about your job–if they are up for it.


Final Tips

Now that you know how to install a window AC unit, maybe you’ll want to utilize a few tips to maximize the efficiency of your unit. Double check that the insulation is done properly as improper insulation will undermine the effects of your unit and drive energy efficiency down. Use blinds to block the sun on the other windows and use an electrical fan to circulate the cool air around the room faster.


We hope that your future window AC installations will be fast and easy. Thanks for reading!

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