When winter hits hard, your HVAC system is already under stress. What you do (or don’t do) during a freeze can be the difference between riding it out comfortably or calling for emergency service at the worst possible time. Here’s the no-nonsense list.

DO: Smart Moves That Help Your HVAC System

• Do keep your thermostat consistent

Set it and leave it alone. Large temperature swings don’t heat your home faster—they just force the system to work harder and longer.

Best practice: Pick a comfortable temp and stick with it.

• Do expect longer run times

During extreme cold, especially with heat pumps, longer cycles are normal. The system isn’t broken—it’s fighting physics.

• Do allow heat pumps to defrost

If you see steam coming off the outdoor unit, relax. That’s a normal defrost cycle, not smoke or failure.

• Do keep vents and returns clear

Furniture, rugs, or boxes blocking vents choke airflow. Poor airflow equals poor performance and higher strain on the system.

• Do keep snow and debris away from the outdoor unit

Clear around the unit so it can breathe. Airflow matters even in winter.

• Do change filters if they’re dirty

A clogged filter during a freeze is like trying to breathe through a scarf. Restricted airflow can cause shutdowns or icing issues.

DON’T: Common Mistakes That Cause Breakdowns

• Don’t crank the thermostat way up

Turning it from 68 to 75 won’t warm the house faster. It will:

Trigger excessive auxiliary heat

Spike electric bills

Stress electrical components

Patience costs less.

• Don’t shut the system off overnight

Turning heat off during a freeze increases the risk of:

Frozen pipes

Long recovery times

Emergency service calls

If you’re home, keep it running.

Don’t block or close vents

• Closing vents doesn’t “push heat” to other rooms. It disrupts system balance and can cause pressure issues.

Don’t pour hot water on the outdoor unit

Thermal shock can crack coils and damage components. If ice forms, let the system handle it.

Don’t rely on space heaters as your main heat

They’re supplemental—not a solution. Overuse can trip breakers, overload wiring, and increase fire risk.

Red Flags That Mean Call for Service

• Cold air blowing consistently
• System turning on and off rapidly
• Breakers tripping
• Ice fully encasing the outdoor unit
• House never reaching set temperature

Ignoring these usually makes the repair bigger and more expensive. That’s not optimism—that’s experience.

Final Takeaway

Winter freezes don’t break HVAC systems—bad habits do. A well-maintained system, paired with smart operation, will keep your home warm and stable even when the weather gets ugly.

If your system struggled during the last freeze, it’s telling you something. Listening now is cheaper than ignoring it until the next cold snap.