Although Wisconsin is known for its long, snowy winters, the summer months can be surprisingly hot and humid. During a typical heatwave, temperatures can climb into the 90s, with humidity levels reaching the 80% range. When your AC isn’t working correctly, it’s more than just a comfort issue. It can pose real health risks, especially for children and older adults. If warm air is coming out instead of cold, something’s wrong.
1. Thermostat Issues
A common reason your AC may blow warm air is an issue with the thermostat. First, check that the thermostat is set to cool mode. You may get room temperature or even warm air if it’s set to heat, fan, or circulate. Also, confirm that the temperature setting is lower than the current indoor temperature.
If the settings are correct and the system is still blowing warm air, the thermostat itself may be malfunctioning. Something as simple as dirty electrical contacts can cause it to misread the temperature or send the wrong signals to your cooling system. Our technicians can inspect and service your thermostat. This may include restarting it, updating its firmware, or resetting your thermostat’s programming.
If the problem is power-related, we’ll check the wiring. If none of these solutions solve the issue, we can work with you to install an upgrade.
2. Restricted Airflow
Your air conditioner relies on steady, unrestricted airflow to keep your home cool. If airflow drops too low, your system can’t circulate enough cold air, and in some cases, you may even feel warm air coming from the vents. One of the most common causes of restricted airflow is a clogged air filter.
Check your system’s filter. If you notice dust buildup on the surface or hear a faint whistling noise when the system is running, it’s likely time for a replacement. Experts recommend replacing your cooling system’s filter every three months. However, you may need to swap yours out more frequently based on factors like how many people live in your home and if you have pets. Many homeowners inspect their HVAC filters once a month to ensure they know when it’s time for a fresh one.
Outdoor obstructions can also reduce airflow. Most systems in the Chippewa Valley include an outdoor unit that houses the condenser coil, compressor pump, and fan. Over time, leaves, branches, and debris can collect around or inside the unit, blocking airflow and reducing performance. Our technicians can remove that buildup, clear the fan, and clean the coils to restore airflow.
Another possible issue is leaky ductwork. Cool air escapes, and hot, humid air from the attic or crawlspaces can enter your ducts. In this case, professional duct sealing or repair is needed to stop the leaks and restore cooling efficiency.
3. Low Refrigerant Pressure
Every air conditioning system relies on refrigerant to absorb heat from inside your home and release it outside. A common misconception is that AC systems slowly use up refrigerant over time. In reality, the refrigerant circulates within a sealed system. If levels drop, it means there’s a leak.
Low refrigerant pressure reduces the system’s cooling efficiency and even causes warm air to blow from your vents. While some leaks can be big, most are micro-leaks that allow the system to keep running but with diminished performance.
Our technicians will inspect your system to locate and diagnose the leak. Once the leak is found, we’ll seal it and replace any worn tubing or other components if necessary. We’ll then recharge the system with the correct amount of refrigerant to restore proper pressure. Once levels are balanced, your AC should resume normal cooling.
4. Compressor Problems
Your compressor has a fan that pulls in outside air, which passes over the coil and carries the heat away. If this process is disrupted, the system can’t remove enough heat from your home. As a result, the air coming from your vents may feel warm even if the system is running.
One possible cause is mechanical wear. Over time, compressor pumps can suffer from worn bearings, lack of lubrication, or internal damage. These issues reduce performance and may eventually prevent the system from cooling effectively. In these cases, our technician may need to service the pump, rebuild specific components, or replace it if the damage is severe.
5. Frozen Air Conditioner
A frozen air conditioner is a serious issue that often signals an underlying problem. The most common cause is a frozen evaporator coil, which stops the system from properly absorbing heat. The blower may continue to push air through your vents, but without active cooling, that air will feel room temperature or even slightly warm.
This freezing often results from restricted airflow, such as when a dirty filter or blocked return vent prevents air from moving across the coil. It can also stem from low refrigerant levels, which reduce the pressure inside the system and cause moisture in the air to freeze on the coil. In some cases, the defrost cycle may not be functioning correctly, allowing ice to build up.
When the coil freezes, the entire cooling process is compromised, and your system can suffer long-term damage if it continues to run in this state. In addition, melting ice can lead to water leaks inside your home, potentially damaging ceilings, floors, or drywall. Our technicians will identify the root cause, safely defrost the unit, and make any necessary repairs to restore efficient cooling and prevent water damage.
6. Electrical Issues
Air conditioners rely on a complex electrical system that includes control boards, wiring, capacitors, relays, and other components. This system not only powers the unit but also manages communication between the thermostat and the AC, as well as between the system’s internal parts. If any of these electrical signals are disrupted, cooling performance will suffer.
A faulty electrical connection can prevent the compressor or fan from starting, or it may trigger erratic behavior like irregular defrost cycles or short cycling. These kinds of issues can also place added stress on motors and other mechanical parts, leading to premature wear.
Our technicians will perform a complete electrical diagnostic to determine whether the system is operating within safe parameters. If not, we’ll make the necessary repairs. That might involve tightening loose connections, replacing frayed or corroded wires, or updating the firmware on the control board. In some cases, the best solution may be to replace the board to ensure long-term reliability and performance.
Trusted AC Diagnostics and Repairs in Wisconsin
Hurlburt is a trusted HVAC provider with more than 65 years of experience. We are a family-owned and operated company serving homeowners throughout Wisconsin, with locations in Eau Claire, Hudson, Menomonie, and River Falls. Our technicians service all air conditioners and heat pumps according to manufacturer specifications, using high-quality parts and materials. Every repair is backed by a one-year warranty on both parts and labor, so you can feel confident in the work we do.
Contact us today with any questions or to schedule a repair appointment.
