You’ve probably already guessed this isn’t a normal part of the operation of your air conditioning system. You would be correct in that assumption. If you have never experienced this the idea can seem far fetched. After all, not many people are used to seeing a block of ice surrounding their compressor on a 95-degree summer day. Air Conditioning and Refrigeration systems freeze for different reasons depending on what is impacting what part of the refrigeration cycle (see below) These reasons can be listed under 4 different categories; airflow loss, refrigerant loss, mechanical, and temperature.
The first reason for you’re a/c system freezing is probably the most common. The freon pressures in your system rely on the absorption of heat in the evaporator section. This is transferred from air that is pulled in from your house into the air handler unit and across the evaporator coil. With a loss of air flow comes a drop in temperature below freezing at the evaporator section causing the water molecules in the air to form frost on the indoor coil which eventually builds into a layer of ice. The most common cause for airflow loss are listed below.
The second category is refrigerant loss. This is another very common cause for a/c systems freezing over. Each system is charged with an exact amount of refrigerant or freon that is used to transfer heat from your home. Age of a system, improper installation, acidity of refrigerant, or manufacturing flaws can cause systems to leak refrigerant. The size and severity of the leak is situation dependent. Loss of pressure in the system cause the temperature of the refrigerant to drop below freezing temperatures and form ice on the evaporator coil and travel outside to the condenser via the copper lineset. In rare cases overcharging a system may result in no superheat and the air conditioning unit to freeze over.
Other causes of an air conditioning system freezing are mechanical related and are listed below.
The last cause for a air conditioning system freezing is temperature. When we are referring to temperature in this circumstance we are talking about the outdoor ambient temperature. A low outdoor ambient temp can cause the pressures in the system to drop below normal and cause freezing of the air conditioner. This problem is usually resolved with a lockout device installed on the air conditioning unit by the manufacturer. Not all systems are equipped with this type of control though. Typically running your A/C system in outdoor ambient of below 60 degrees is not reccomended. Freezing can also occur when the indoor temperature at the thermostat is set too low. This puts unnecessary wear and tear on the system. On a residential split system the indoor temperature should not be set below 68-70 degrees unless equipped with controls that prevent a freezing situation.
When your air conditioning system freezes over it can cause the freon to return to the compressor in a liquid form and cause slugging of the motor. Modern scroll compressors are better equipped to handle this situation than older style units. However it can still cause damage to the system and should be assesed by a professional if it ever occurs. The friendly professionals at Top Gun Air can provide an honest assesment and leak detection service if needed. For scheduling of appointments check us out online. If you have questions regarding freezing of your system and would like to have one of our technicians guide you on the best course of action, give us a call at (682) 214-0431. We hope you found this article informative and helpful.