Frequently Asked Questions
Everything you need to know about choosing, installing, and maintaining air conditioners — answered by our experts.
What size air conditioner do I need?
The general rule is 20 BTU per square foot of room space. However, factors like ceiling height, sun exposure, climate zone, and number of occupants affect the actual requirement. Use our BTU Calculator for a personalized recommendation.
How often should I clean my AC filter?
For window and portable units, clean the filter every 2 weeks during heavy use. Central HVAC systems with 1-inch filters need monthly replacement; 4-inch filters last 3-6 months. Mini-split filters should be cleaned every 2-4 weeks.
Which is more energy-efficient: window AC or mini-split?
Mini-splits are significantly more efficient. They typically have SEER ratings of 20-30, while window units are rated 10-15 CEER. However, mini-splits cost more upfront. For occasional use in a single room, a window AC may be more cost-effective overall.
Can I install a mini-split myself?
Some brands like MrCool offer DIY-friendly models with pre-charged lines and quick-connect fittings. You will still need a licensed electrician for the dedicated circuit. Traditional mini-splits require professional installation due to refrigerant handling regulations.
Why is my air conditioner leaking water?
The most common causes are: a clogged condensate drain line, a dirty air filter causing ice buildup, or (for window units) incorrect installation angle. Check our troubleshooting guide for step-by-step fixes.
Do portable air conditioners really work?
Yes, but they are less efficient than window ACs or mini-splits. Single-hose models lose 30-40% efficiency due to negative pressure effects. Dual-hose models perform much better. Portable ACs are best when other options are not possible (rentals, incompatible windows).
What does SEER rating mean?
SEER (Seasonal Energy Efficiency Ratio) measures how efficiently an AC converts electricity into cooling over an entire season. Higher SEER = lower operating costs. The minimum for new central AC systems is 14-15 SEER (depending on region). High-efficiency units reach 20-26 SEER.
Should I cover my outdoor AC unit in winter?
Generally no. Full covers trap moisture and attract rodents. If you have a central AC (not a heat pump), you can place a piece of plywood on top to deflect falling debris. Heat pump outdoor units should never be covered as they operate year-round.
How long do air conditioners last?
Window AC units last 8-12 years, central AC systems 15-20 years, and mini-splits 12-20 years with proper maintenance. The biggest factors are usage intensity, maintenance regularity, and climate.
Is it cheaper to run one central AC or multiple window units?
If you cool 3+ rooms for 8+ hours daily, central AC is usually cheaper per BTU. If you only cool 1-2 rooms during specific hours, window units or a mini-split are more economical since you only cool the spaces you are using.