519. Why Your HVAC Unit Isn't Cooling and What You Can Do About It
28 Jan 2026 · 6 min
Derek Cole walks through why your AC stops cooling and what you can fix yourself. Check your thermostat settings, replace the air filter every 30 to 90 days, and clear debris from the outdoor unit. If you hear hissing or see frost on the copper line, you have a refrigerant leak and need a professional.
Chapters
Why your H Vac unit isn't cooling and what you can do about it. You know, it's hard to, to beat the refreshing feeling of kind of walking from outside to inside and having that cool air in your home. And it can be frustrating when it's not that way. Right? It's hot outside, it's hot inside, or it's hot when you're trying to sleep. You always sleep better when it's cool inside and the body temperature goes down versus being warm. So why is your AC unit not cooling and what can you do about it? Number one, check your thermostat. This sounds so simple, but it's missed by so many. Check. Check your thermostat. Make sure it is on the right mode. We have come, you know, off, winter off, you know, fall time. Make sure it is going from heat to cool, heat to cool. Make sure your thermostat is on the cool mode to get cool air. It is. It sounds ridiculous, but really, that's, that's some of our phone calls. Our tech goes out there and the thermostat is simply on the wrong mode. Or if it's on auto, it's on the wrong temperature. They wanted to be lower, but the temperature is, is wrong on the thermostat. So number one, check your thermostat. Number two, check your air filter. Check your air filter. Now. Your air filter should be changed 30 to 90 days, depending on your usage and what needs to happen now. If you see the filter is dirty sooner, of course, change it sooner. But always check it every 30 days. Change it every 30 to 90 days, depending on your usage. Check the condition coil the outside coal. Make sure it's not clawed. You don't have debris, you don't have trees, plants, something blocking the airflow. It's going, the outdoor condenser coil is going to release the heat that's in the house. AC works by removing heat. It's just heat transfer. If you have a heat pump, it stops away in the winter. You, you want to extract the heat from outside and bring it inside. In the cooling season, you want to extract the heat from inside and take it outside. So you're just removing heat. It's about heat transfer. Make sure that condenser coal is not clogged with debris. Shrubs, trees, grass, scubbings, anything that makes the unit work harder because it's all about heat transfer. So copper or aluminum are great conductors of heat. That's why your coals are made of copper or aluminum, because they are great conductors of heat. Now the situation is when they get dirt or debris on acts as insulator, it restricts that heat transfer. So the harder the system has to work, the more energy it pulls, the more likely you are to have a breakdown again. That's why we emphasize the importance of maintenance on your system, is to keep that system clean. Refrigerant, this is a big one. Refrigerant leaks could be a problem. A sound of a leak could be kind of a a hissing noise or the system actually could frost up or freeze up. In the summertime you go out there and it's a black ice, black ice on your copper line set. Going to the unit. Refrigerant leaks. Could be. It could be a challenge, but you need to call a professional. Either way, when you start dealing with refrigerant or coals, I would always get an all pro technician involved because you need a pro to look at that also. Finally, consider maintenance. It could be simple as going back to that clogged coil. Could be simple as multiple things need to be cleaned, need to be checked, need to be calibrated, need to be adjusted. Professional maintenance is the best thing you can do for your system to make sure it's running at optimal performance. Again, engage in all pro technician to take care of that for you. There's nothing better than preventative maintenance on your system to help prevent breakdown this serum. So that's a few reasons why your unit is probably not cooling. A few of those you check out. But either way, I would get an all pro tech to your home to see what's going on. And if you have not had a maintenance definitely I recommend going and doing that.
More from Derek


713. Fan "On" or "Auto"? The Thermostat Setting That Could Be Making Your Home More Humid


712. Why Is My Upstairs Always Hotter Than Downstairs? The Truth Every Homeowner Should Know