5 Reasons Older Heat Pumps & HVAC Systems Struggle on Hot Summer Days

When temperatures soar above 25-30 °C, older heat pumps and HVAC systems often can’t keep pace. Rather than a single flaw, it’s usually a combination of issues that drag down performance—and your comfort. Let’s dive into the most important causes and what you can do about them.

1. Outdated Efficiency Ratings

  • Older SEER vs. Modern Standards: Units 15–20 years old typically carry a Seasonal Energy Efficiency Ratio around 8–10, whereas today’s systems hit 16–20.
  • Real‑World Impact: An old unit must run 30–50% longer to move the same amount of heat, leading to uneven cooling and higher electricity use.
  • Takeaway: Upgrading to a high‑efficiency model restores capacity and cuts run‑times dramatically.

2. Refrigerant Loss & Charge Problems

  • Why It Matters: Refrigerant carries heat away from your home. Just a 10–15% leak means coil temperatures never drop enough to extract sufficient indoor heat.
  • Symptoms: Longer cooling cycles, poor humidity control, and steadily rising bills.
  • Solution: A professional leak check and recharge can recover much of your lost performance—if the system’s under‑charge isn’t too severe.

3. Airflow Restrictions & Duct Leaks

  • Clogged Filters: A dirty filter can reduce airflow by 20–30%, starving the evaporator coil of warm air to cool.
  • Leaky Ductwork: Up to 20% of conditioned air may be lost through holes or disconnected joints, cooling attics instead of living spaces.
  • Action Steps: Change filters every 3 months, seal and insulate ducts, and ensure vents are unobstructed.

4. Improper Equipment Sizing

  • Original Errors: Cost‑cutting installers sometimes undersize units, leaving them incapable of meeting peak loads.
  • Home Changes: Renovations, added windows, or poor insulation can push cooling needs beyond the system’s design.
  • Effect: Short cycling in mild weather and complete failure on the hottest days.
  • Fix: Have a load calculation performed; right‑sized replacements run more efficiently and maintain comfort.

5. Worn Components & Neglected Maintenance

  • Compressor Wear: After years of use, internal parts lose efficiency—reducing cooling capacity even when everything else checks out.
  • Dirty Coils: Every 2 mm of dust on your evaporator coil can cut heat transfer by 10%, forcing longer run times.
  • Preventive Care: Annual tune‑ups catch refrigerant leaks, clear coils, tighten electrical connections, and lubricate motors—keeping your system performing near factory specs.

Conclusion & Next Steps

Older HVAC equipment struggles under heatwaves for predictable reasons: low efficiency, lost refrigerant, poor airflow, wrong sizing, and worn parts. Restoring reliable cooling starts with:

  1. Professional Inspection: Check refrigerant, airflow, and component health.
  2. Routine Maintenance: Schedule yearly tune‑ups and stay on top of filter changes.
  3. Right‑Size Your System: Ensure your unit matches your home’s current cooling load.
  4. Consider Upgrading: Modern, high‑efficiency heat pumps deliver up to 50% more cooling power for the same electricity.

Ready to beat the heat with dependable performance?
Contact LES Mécanique at (514) 333-6968 for a system assessment and get back to comfortable summers.

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