It may surprise some homeowners to learn that even when it is hot outside, their air conditioner can freeze. This leads to a number of problems and could result in serious and expensive damage to the system. There are steps you can take to prevent this from happening, or at least to minimize the damage.
1. Low refrigerant levels
Low levels of refrigerant, due to leaks or improperly charged refrigerant, cause the pressure to drop in the air conditioner’s evaporator coil making it too cold. This allows moisture in the air to form ice on the coil.
Contact your HVAC professional to fix the leak and recharge the system.
2. Dirty air filter
A clogged filter restricts airflow and can cause the temperature of the system’s evaporator coil to drop below freezing. Humidity collects on the coil and turns to ice.
Replace or clean the air filter every 30-90 days, depending on how quickly it fills up.
3. Closed supply registers
Closing supply registers in unused rooms may seem like a money-saver, but can result in enough air restriction in the system that the AC freezes.
Keep at least three-quarters of the home’s supply registers open at all times.
4. Insufficient fan speed
A certain amount of air needs to blow over the evaporator coil. If the fan isn’t blowing fast enough this can result in freezing.
Ask your technician to increase the fan speed.
5. Thermostat problems
A faulty thermostat could cause the air conditioner to freeze by having the system run all night unnecessarily.
Have your thermostat checked and replace it if necessary.
6. Drainage problems
A blocked drain will cause water to back up. The water can freeze all the way back to the evaporator coil.
Check the drain regularly and clear any clogs, particularly during the hottest days of summer.
The best way to prevent your air conditioner from freezing is to schedule yearly maintenance with your HVAC professional who will make sure your system is clean and running efficiently, with no refrigerant leaks.