When we get those really hot days with a high heat index, as it is today (with a heat index going to be near 110F) we get a lot of calls about systems not keeping up properly. This is a great opportunity for us to share some back story on how size Air Conditioners, and what you can look at. You may be able to increase capacity yourself!
Sizing of Air Conditioners in Wisconsin
Typically when we are sizing Air Conditioners for the Fox Valley area, we are utilizing a design temperature of 90F. That means we are sizing the Air Conditioner to function for that temperature. Problem is, when we are over 90F we are asking more than what it is designed for. This can mean when we get the extreme weather like we had today (6/30/2026) a system may run and run and only be able to get down to 74F, and not the 68-70F you want. May sound frustrating, but trust us… it is a good thing.
When we size Air Conditioners we need to take into considering what the conditions will be like MOST of the time. If we sized stuff for worst case scenarios, everyone’s Air Conditioner may be a half-ton larger, and when we want it on with a low 80’s high out, it will cool things down too quick and won’t dehumidify, causing an awful clammy feeling in the house. That’s not comfort.
If your system is cooling but not getting down low, what can you do?
There is a chance that you can do things to help with the capacity on the worst days of the summer. There are two things we recommend doing.
- Check your furnace filter. If your filter is at all restricted it can slow down overall air flow and deliver suboptimal cooling into your home. If it dirty replace it, and please do not run without a filter, if you can help it.
- Wash your outdoor condenser out. If your outdoor unit is plugged up, it lowers the amount of cooling your Air Conditioner can do because it’s unable to exhaust the heat outside properly. It’s important if you do wash your coil to turn the power off to the unit first, and we recommend spraying from the inside out (which varies from a lot of youtube videos).
It could also be an issue with refrigerant charge, but that is not something you can check without gauges. This is also part of getting an annual tune-up visit on your Air Conditioner. You can make sure that there isn’t a slow leak by comparing numbers year to year.
If you’re in need of service, please give us a call at 920-734-1436 for fastest service. In extreme weather we may be dealing with high volumes of calls, so it could potentially be a day or two, but we do everything we can to get there as soon as possible.