For the last few years, I’ve lived in homes with window-mounted air conditioning units. One of the most important lessons I’ve learned is to consistently drain my AC-unit of water after rain storms.
If you allow water to accumulate in your AC units, they will get weaker, become louder, and eventually leak consistently. My advice to you for a cool and frugal summer is to lean your window-unit ever so slightly out your window after each rain storm.
Have you never drained your AC unit? Then you should probably take your AC-unit, place it in the shower (UNPLUGGED), and allow the water to drain out over 15 minutes.
Making sure that your air conditioner is free of rain water will keep your air running smoothly through the Summer! Also, consider replacing the filter on your air conditioner – I tend to let mine get dusty as hell, be better than me for I am a simple messenger.