The most common problems that cause a lack of airflow include frozen coils, broken fan and restricted airflow due to dirty air filters or vent obstruction. However, there are many other issues that can lead to minimal airflow, so it may be necessary to ask the professionals.
If your air handler is running but not blowing air, there are two likely scenarios: either a broken AC blower belt or an issue with the motor itself. If the air handler is humming or buzzing but not making the mechanical sounds of a motor running, you're most likely talking about an issue with the motor itself.
Frozen Evaporator CoilA dirty air filter or a blocked return vent can greatly restrict airflow through your unit and cause the evaporator coil to freeze over. When this happens, the air is blocked from passing over the coils and into your duct system to be pushed out through the vents.
If the AC compressor is not working but the fan is running, potential causes include a faulty capacitor, electrical issues, low refrigerant levels, or compressor failure. It's best to consult a professional HVAC technician to accurately diagnose and repair the problem.
Coil is frozen. If the fan is spinning, but no air is moving, this is likely the culprit. If your coil is frozen, you probably have a refrigerant leak.
Check Your Circuit Breaker
When the fan is turning but the air conditioner's compressor is still, another likely problem is that electricity isn't traveling to the outside unit. The compressor is outside, thus, it's still, but the fan is still connected to the interior power.
The most common problems that cause a lack of airflow include frozen coils, broken fan and restricted airflow due to dirty air filters or vent obstruction. However, there are many other issues that can lead to minimal airflow, so it may be necessary to ask the professionals.
The short answer: Definitely not. (Unless you have manually engaged your outside fan to run constantly, but it shouldn't be running for hours on it's own.) If your HVAC is functioning correctly, it should keep your house cool by cycling on for 15-20 minutes at a time—with distinct pauses in between each cycle.
If you see the AC fan not spinning, the fan motor may have burnt out. If the fan motor has been working very hard and hasn't received regular annual or biannual maintenance, motor bearings can break down. Fan motors can be quite pricey to fix or replace. You may end up having to replace the entire system.
How do I fix an AC that isn't blowing cold air? Start by checking the thermostat settings, air filter, and refrigerant levels. If necessary, replace the air filter or adjust the thermostat. If these steps don't work, a professional should inspect the compressor or refrigerant levels.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
The first place to check is your thermostat. Ensure it's set to cool and at a temperature that should trigger the air conditioner to startup. Ensure that the thermostat has operating batteries and is wired correctly. Finally, inspect your vents to ensure they are free of obstructions and not blocked by furniture.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.
Resetting your AC unit usually involves turning off the power, waiting for a specific duration, and then turning it back on. This process can vary slightly depending on the make and model of your unit. Typically, you'll find a reset button on the outdoor unit. Press and hold it for a few seconds.
The main reasons your AC unit outside is not turning on could be something that has tripped the circuit breaker, something is blocking the fan's airflow, or the condensing unit is damaged. Other potential issues could be the thermostat isn't set correctly or the compressor could be malfunctioning.
Allowing the fan to run uninterrupted, there is a more even distribution of warm or cool air circulating through your home. This will help reduce hot or cold spots within your home. There could be reduced stress on the fan from less frequent starts and stops, which could potentially help extend its lifespan.
Dirty air filters or coils
Simple – a dirty filter or the evaporator coil will heavily impede the airflow, which may cause the compressor to overheat and shut down as a precautionary measure. You should replace the air filter and remove any dirt from the evaporator coil located inside your air handler.
You can generally identify a blocked air duct by a distinct drop in heating and cooling efficiency, increased energy costs, and occasionally a musty, dusty smell throughout the home. The blockage usually comes over time, by a buildup of dust and debris that just accumulates until it begins choking the system.
An outside AC fan not spinning could be caused by power supply issues, a faulty capacitor, a burnt out motor, contactor issues, wiring problems, debris or obstruction, a faulty thermostat or control board, or frozen evaporator coils. Contact your local Carrier dealer to help troubleshoot the issue further.
Whether the blades aren't spinning or the fan is making tons of noise, most issues with an electric fan are caused by poor lubrication or blockages in the vents. To solve most problems with an electric fan, disassemble the fan, lubricate the central pin and bearings, and clean out the vent and motor case.
A non-working furnace fan typically stems from electrical issues, mechanical failures, or control problems. Start troubleshooting by checking your circuit breaker, thermostat settings, and air filter condition.