| Square Footage | Furnace BTU |
|---|---|
| 1,000-1,200 sq. ft. Home | 40,000 - 60,000 BTU |
| 1,200-1,500 sq. ft. Home | 60,000 BTU |
| 1,500-1,800 sq. ft. Home | 60,000 - 80,000 BTU |
| 1,800-2,500 sq. ft. Home | 80,000 - 100,000 BTU |
| 2,500-3,500 sq. ft. Home | 100,000 to 120,000 BTU |
No one wants their air conditioner to stop working—especially on the hottest day of the year. But the truth is, most AC problems are common and fixable, especially if you know where to look.
In this guide, we’ll go over 16 of the most frequent air conditioner problems Canadian homeowners face, plus what you can do to fix them—or when to call in a pro.
Banging, buzzing, or rattling? That’s your AC trying to get your attention.
| Sound | Possible Issue |
| Banging | Loose internal part (fan blade, piston) |
| Buzzing | Loose wires, frozen coil, dirty parts |
| Clicking | Faulty thermostat or relay switch |
| Hissing | Refrigerant leak or pressure build-up |
| Rattling | Loose screws or debris inside |
Quick Fix:
Check where the noise is coming from—indoor unit, outdoor unit, or vents. Clear out debris, tighten loose parts, and gently clean fan blades. Pad any rattling metal with foam until a pro can fix it properly.
Even a brand-new air conditioner can freeze if something’s wrong. Common culprits:
Quick Fix:
Turn off the AC, set the fan to “ON”, and replace the air filter. Open all vents. If it keeps freezing, schedule a technician to check for leaks or airflow issues.
Your AC may not turn on due to:
Try This:
Reset your breaker, replace thermostat batteries, and clean/replace your air filter. Still not working? You may need a tech to inspect internal wiring or capacitors.
Repeated fuse blowouts point to deeper electrical issues, like:
What to Do:
Replace the filter, inspect for exposed wires, and clean the outdoor unit. For safety, let a certified electrician or HVAC tech handle any fuse or wiring repairs.
If your AC runs non-stop, check:
Try:
Reset the system and clean your filter. If it continues, schedule a maintenance visit for contactor testing.
Blinking lights are error codes. They often signal issues like:
Solution:
Refer to the user manual or check your brand-specific error code guide. If it persists, call a certified technician.
A refrigerant leak leads to:
What to Watch For:
If your unit blows warm air, runs too long, or has ice on the lines, turn it off. Only a licensed pro can fix the leak and recharge refrigerant safely (per Canadian regulations).
You expect cool air—not a sauna!
Possible reasons:
Fixes:
Set to “cool,” check filter, and inspect the outside unit. Still warm? Call a tech to check the compressor or refrigerant.
Outdoor water is normal. But indoor leaks mean:
Try:
Flush the drain line with vinegar or warm water. Clean the air filter. If it still leaks inside, call a tech to check the drain pan and coils.
Strange smells? Here’s a quick breakdown:
| Smell | Likely Cause |
| Musty | Mold in ducts or drain pan |
| Dirty socks | Dirty coil |
| Burning | Motor/electrical issue |
| Rotten eggs | Dead animal near unit |
| Sweet/chemical | Refrigerant leak |
What to Do:
Clean/replace the filter, pour vinegar down the drain line, and schedule coil cleaning if needed.
Short cycling = quick on/off bursts. Can be caused by:
Fixes:
Move items away from the thermostat, change the filter, and get a pro to check if the unit’s too big or refrigerant is low.
Older homes often have duct leaks—air escapes into attics or basements.
Signs:
DIY Tip:
Use metal foil tape (not duct tape) to seal visible leaks. For full-home sealing, ask about Aeroseal or similar technologies.
🔗 Related: Learn about duct sealing and energy savings
High humidity indoors while the AC is on?
Possible causes:
Solution:
Set the fan to AUTO, not ON. Lower fan speed and clean filters. For persistent issues, have your AC inspected.
Bedroom hot, basement freezing? Blame:
Fix:
Open all vents, move furniture, and consider zoning systems for better balance. Also, use ceiling fans to circulate air.
Slow cooling may be due to:
Try:
Close windows/doors, replace filters, clean the coils, and shade the outdoor unit if needed.
Your AC may be working too hard. Causes:
Tips to Save:
Most of these issues have quick fixes—but the best fix is prevention. A professional tune-up can keep your air conditioner efficient, quiet, and long-lasting.
👉 Compare local quotes from trusted HVAC pros and keep your AC cool, clean, and cost-efficient.
| Problem | Quick Fix |
| Noisy AC | Clean debris, tighten parts |
| Freezing unit | Replace filter, run fan |
| Not turning on | Reset breaker, replace batteries |
| Blowing warm air | Check thermostat, clean filter |
| Water leak indoors | Flush drain line |
| Bad smells | Clean coils and filters |
| Uneven cooling | Open vents, seal ducts |
| High bills | Smart thermostat, regular maintenance |
