How to Prepare Air Conditioner for Winter

Properly winterizing your air conditioner protects it from cold weather damage, prevents pests from nesting inside, and ensures it's ready to perform when summer returns. Here's what to do for each type of AC unit.

Why Winterize Your AC?

• Prevents ice and frost damage to coils and components
• Stops rodents and insects from nesting inside the unit
• Protects the outdoor condenser from debris, ice, and UV damage
• Prevents mold and mildew from growing in a dirty, damp unit during storage
• Extends the lifespan of the unit

Window Air Conditioner

Option A: Remove and Store (Recommended)

1. Clean the unit thoroughly before storing — see our guide on how to clean a window AC
2. Remove the unit from the window
3. Drain any remaining water by tilting the unit slightly and letting it drain
4. Let it dry completely for 24 hours before storing
5. Store upright in a cool, dry location — a garage, basement, or closet. Cover with a cloth or the original box.
6. Seal the window with an insulating panel or weatherstripping to prevent cold drafts

Option B: Leave in Window with a Cover

If removing the unit isn't practical, use an outdoor AC cover to protect it from the elements.

The Luxiv Window AC Unit Cover is waterproof, dust-proof, and insulating — it protects the outdoor portion of the unit from rain, snow, ice, and debris while also reducing drafts through the unit into your home. Make sure to remove the cover before running the AC in spring.

Important: Never run the AC with the cover on — it will overheat.

Portable Air Conditioner

1. Drain all water from the tank and drain line completely
2. Clean the filter and let dry fully
3. Clean the exhaust hose and store it without kinking
4. Wipe down the exterior
5. Store upright in a dry location, covered to keep dust out

Split / Mini-Split Air Conditioner

Split systems with heat pump function can often run year-round and don't need winterizing in the same way. However, you should still:

1. Clean the indoor unit filters before the heating season
2. Clear the outdoor unit of leaves and debris
3. Check the outdoor unit drainage — ensure the drain holes at the bottom aren't blocked so ice melt can drain freely
4. Do NOT cover the outdoor unit of a heat pump — it needs airflow to operate in heating mode
5. If the unit is cooling-only (no heat pump), you can cover the top of the outdoor unit with a board or breathable cover to protect from falling ice and debris, but leave the sides open for ventilation

Central Air Conditioner (Outdoor Condenser)

1. Turn off the power at the outdoor disconnect box — this prevents the unit from accidentally running in cold weather
2. Clean the condenser coils with coil cleaner and remove debris
3. Clear the area around the unit of leaves, branches, and vegetation
4. Cover the top only with a piece of plywood or a breathable cover to protect from falling ice and debris. Do not wrap the sides — moisture trapped inside causes corrosion and attracts pests.
5. Check refrigerant lines — ensure the insulation on the lines is intact

General Tips

• Always clean before storing or covering — mold grows in dirty, damp units over winter
• Add condensate pan tablets to the drain pan before shutting down for the season to prevent algae growth
• Note any issues you noticed during the season so you can address them before next summer
• Schedule a professional service in spring rather than autumn — technicians are less busy and you'll catch any issues before you need the AC

Spending 30–60 minutes winterizing your AC in autumn can add years to its lifespan and save you from a nasty surprise when you turn it on next summer.