Why Did Your Heat Work During the winter Storm but Fail Afterward?
Your heating system made it through the coldest part of the winter storm—then stopped working as temperatures began to improve. Although the timing feels strange, prolonged operation, ice accumulation and changing conditions during a thaw can reveal HVAC problems that were already developing.
Here are several reasons heating systems fail immediately after severe Middle Tennessee winter weather.
Long Runtimes Expose Worn Components
Furnaces and heat pumps may operate almost continuously during extreme cold. Long heating cycles do not automatically damage properly operating equipment, but they can expose components that were already worn or close to failing.
Post-storm breakdowns may involve:
Blower motors
Capacitors
Contactors
Relays
Electrical connections
Ignition components
Limit switches
Heat-pump fan motors
The storm may not have created the original problem. Instead, sustained operation may have brought an existing weakness to the surface.
Ice Can Interfere With Heat-Pump Operation
Heat pumps naturally develop some frost during cold-weather operation and use a defrost cycle to remove it. Thick ice that covers the outdoor coil or prevents the fan from moving is not normal.
After a storm, ice-related problems may involve:
A malfunctioning defrost control
A damaged sensor
A frozen outdoor fan
Blocked drainage beneath the unit
Falling ice damage
Water from gutters refreezing on the equipment
Low refrigerant caused by a leak
The U.S. Department of Energy explains how air-source heat pumps transfer heat between indoor and outdoor air. Because the outdoor unit operates during winter, proper airflow and defrost operation are essential.
Do not chip ice from the unit or pour boiling water onto it. These actions can damage the coil, fan, cabinet or electrical components.
Auxiliary Heat May Have Hidden the Problem
During extreme cold, a heat pump may use auxiliary heat to help maintain the thermostat setting. That supplemental heat can temporarily mask a problem with the heat pump itself.
Once outdoor temperatures rise and the thermostat stops calling for auxiliary heat, homeowners may notice:
The system blows cooler air
Indoor temperatures begin falling
The heat pump runs continuously
The outdoor unit does not operate
The thermostat displays an error or auxiliary-heat warning
An HVAC technician can determine whether the primary heat pump, auxiliary heat or thermostat controls are responsible.
Power Interruptions Can Affect HVAC Controls
Winter storms may cause brief power outages, voltage fluctuations or tripped breakers. After power is restored, thermostats, control boards and safety switches may not resume normal operation.
Before calling for service, you can safely check:
Whether the thermostat has power
Whether it is set to “Heat”
Whether the temperature setting is above room temperature
Whether the HVAC breaker has tripped
Whether the filter is severely clogged
Reset a tripped breaker only once. If it trips again, leave it off and call a professional. Repeated resetting may expose the equipment to further electrical damage.
Frozen Condensate Drains Can Shut Down Some Furnaces
High-efficiency furnaces create water during operation. That condensate must drain away properly.
If a drain or exterior termination freezes, the furnace may activate a safety switch and stop operating. The problem may become more noticeable as temperatures fluctuate and ice begins moving or refreezing.
Do not bypass a safety switch. A technician should determine why the condensate is not draining and correct the underlying problem.
A Dirty Filter Can Cause Overheating
A heating system that operated for long periods during the storm moved a significant amount of air through its filter. If the filter was already dirty, restricted airflow may cause a furnace to overheat and activate its high-limit safety control.
Possible symptoms include:
The furnace starts and stops repeatedly
The blower continues running without warm air
Airflow feels weak
The system shuts down before reaching the thermostat setting
Replace a visibly dirty filter with the correct type and size. If the system continues shutting down, professional diagnosis is needed.
Thawing Can Reveal Storm Damage
Ice and snow can temporarily conceal damage around an outdoor HVAC unit. As conditions thaw, homeowners may discover:
Bent fan blades or grilles
Water entering electrical components
Damaged wiring
A shifted or unstable equipment pad
Debris inside the unit
Drainage problems around the equipment
Inspect the area only from a safe location. Avoid standing beneath rooflines where snow or ice may fall.
When Should You Turn the Heat Off?
Turn the system off and request service if you notice:
Burning or electrical odors
Smoke or sparks
Loud grinding or scraping
The outdoor fan striking ice
A breaker that repeatedly trips
Water around electrical components
A gas odor
A carbon monoxide alarm
If you smell gas or a carbon monoxide alarm activates, leave the building immediately and contact the gas utility or emergency services from a safe location.
Preventing the Next Post-Storm Breakdown
Regular heating maintenance can identify worn components, restricted airflow and defrost problems before the next cold snap.
Helpful preventive steps include:
Checking the filter monthly
Keeping outdoor equipment clear of leaves and debris
Repairing gutters that drain onto the unit
Scheduling seasonal HVAC maintenance
Testing carbon monoxide alarms
Addressing unusual noises before severe weather
Avoiding repeated breaker resets or system restarts
RCI Mechanicals provides heating repair and HVAC maintenance in Murfreesboro and Middle Tennessee for residential, commercial and industrial properties.
If your heat stopped working after a winter storm, contact RCI Mechanicals for an inspection. A professional diagnosis can determine whether the problem involves airflow, electrical components, ice damage or the heating equipment itself.