There are several factors that can cause system freezing. Most need to be corrected by your local Lennox Dealer.
One thing you can do to prevent or correct this problem is to make sure the filter is clean or replaced. You can check to see if airflow is restricted.
After replacing or cleaning the, you can speed up the thawing process by turning the system off and turning on 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 your local Lennox Dealer to correct the problem.
In some cases, freezing is caused by a leak in the refrigerant lines. Weak solder joints, friction from piping rubbing or vibrating against an object, open valves or loose fittings are all factors that can cause leaks. When determining whether to have the system repaired or replaced, the age of the system and the nature and location of the leak are important considerations.
Dirty evaporator coil
Over time, the evaporator coil will become dirty. When this happens, you will begin to lose airflow, slowly enough that you probably would not realize it until it freezes up or cooling performance is compromised. At this point, you will need to contact your local Lennox Dealer to correct the problem.
Defective blower motor or relay
A blower motor not running at the proper speed or not running at all is another factor that can cause freezing. Motor operation may be intermittent, 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 Lennox Dealer to correct the problem.
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