There are an abundance of possibilities that can cause your HVAC system to freeze up; almost all of them usually need to be corrected by a professional technician. Determining the air filter is clean or replaced and making sure the airflow is not restricted are about the only tasks a homeowner should safely identify or handle themselves.
Low refrigerant: In some cases, freezing up is initiated by a leak in the refrigerant lines. Weak solder joints, friction from piping rubbing or vibrating against an object, leaking valves or loose fittings can cause leaks. The length of time your system has been installed and the nature and location of the leak are the determining factors on whether to have the system repaired or replaced.
Dirty evaporator coil: Over time, the evaporator coil will become dirty. On these occasions, the results are similar to those of having a dirty filter. Gradually you will lose airflow, slowly enough that you probably would not realize it until it freezes up or is not cooling adequately. You will need to contact your local Service Experts sales and service center to remedy the problem.
Defective blower motor or relay: A blower motor running at an improper speed or not running at all can cause freezing. It can also be sporadic, starting at full speed and slowing down after it heats up. Or a relay could cause it to start one time and not the next. In either case, you will need to contact your local Service Experts sales and service center to correct the problem.
Should you discover that your system was freezing due to a dirty air filter, after replacing or cleaning the filter, you can hasten the thawing process by turning the system off and then turning on only the fan. If you have a heat pump system, you can try turning the system to heating mode until the ice has melted. After the ice has melted, switch the system settings back to normal. If the system refreezes, contact Neal Harris Service Experts Heating, Air Conditioning & Plumbing in Kansas City to solve the problem.