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B & W Heating And Cooling


Why Is My A/C Unit Freezing Up

A/C Freezing
A/C freezing problems are the root cause of many summertime service calls by Edwardsville, IL, HVAC technicians. When an AC unit “freezes up,” it limits or even halts the HVAC system’s ability to cool the home. You may notice the evaporator coil takes on a frosty or frozen appearance, and your unit starts blowing hot air. Trane, the manufacturer of many HVAC systems, says there are a few reasons for this common A/C problem. A/C Freezing

Airflow Blockage

Closed air supply registers and dirty air filters are common causes of airflow blockages that result in A/C freezing problems. In order for the evaporator coil to work efficiently, airflow should be unrestricted; this keeps condensation from building up, freezing, and causing your unit to malfunction. Prevent this from happening by keeping your supply registers in their open position and changing your air filter at least monthly.

Problems with Drainage

When the weather is humid, there is more condensation of water vapor within your A/C unit. Normally, the unit condenses the vapor, forming a liquid that makes its way through the lines in the unit and exits via a drain pipe. Anything blocking the lines running to this pipe can cause water to remain stuck inside and result in a frozen unit.

Issues with the Thermostat

Setting the thermostat too low can force your A/C unit to run continually, and the effect of this is that the condenser’s temperature drops below the freezing point. This can also happen as a result of a faulty thermostat. Either way, the unit freezes over, and you’re stuck waiting for a fix (or a thaw). A/C Freezing

Refrigerant Level

If your A/C is low on refrigerant, then the pressure in your system drops along with the temperature, resulting in overchilling of the evaporator coil and freezing. Low refrigerant can indicate a leak that may be repairable. Depending on your A/C system’s age, replacement of the system may be recommended.

What Can You Do?

If you notice your A/C system is frozen, turn it off right away. Keep it off long enough for it to defrost, and then perform some standard A/C maintenance. Clean your filter or replace it with a new one, and then remove any visible dirt or debris. This is sometimes enough to fix the problem. If not, contact us at B & W Heating and Cooling. One of our HVAC specialists to check the refrigerant, fix the thermostat, or even replace your system.