In addition to cooling the air, your central air conditioner is meant to manage the humidity in your home. If the air from your vents feels moist or humid when your AC is running, it's a clear sign of a problem. A few different problems can cause a central air conditioner to produce humid air, but they are often easy for an HVAC contractor to resolve. Here are two possible causes behind humid air from your central air conditioner.
1. Ice On Evaporator Coils
Evaporator coils are the component inside central air conditioners that cool the air directly. As air passes through the coils, cold refrigerant inside the coils draws heat out of the air. At the same time, condensation from the air collects on the coils, making it less humid.
Your evaporator coils can freeze up if your air conditioner is low on refrigerant. Freezing may also occur if the AC is used under high load for an extended time, or when the outdoor temperature is low. Frozen evaporator coils can't draw heat and moisture from the air effectively, so the air from your vents will be moist.
If the coils are frozen, shut off your AC for at least an hour and allow them to thaw. Alternatively, you can set your thermostat fan setting to "On" to run the furnace blower without your AC. This can potentially thaw the coils faster. Call an HVAC contractor to check your AC refrigerant levels if the coils continue to freeze when you use your air conditioner.
2. Gaps In Your Ductwork
Unconditioned air mixing into your ductwork air supply is another possible cause of humid air from your AC. Punctures or loose connections at certain points in your ductwork may draw in air that has never been cooled or dehumidified by your air conditioner.
Locating gaps in your ductwork is always challenging. However, humidity problems help to narrow down the potential problem areas in your ductwork. It's highly unlikely that a return duct leak would cause humid air from your vents. Instead, you'll know that the leak most likely lies on a supply duct that delivers air to the rooms in your home.
Central air conditioners aren't meant to blow damp air through your home under any circumstances. If you notice this problem in your own home, you can start to narrow down the causes by first inspecting your evaporator coils. Call an HVAC air conditioning contractor for a professional inspection so your air conditioner can keep your home's humidity at a comfortable level.