Common HVAC Issues and How to Troubleshoot Them

When temperatures swing from scorching summer days to chilly winter nights, a reliable heating and cooling system isn’t a luxury — it’s a necessity. But even the best air conditioners and heaters can sometimes falter.

Whether you have a reverse cycle system, evaporative cooler, or ducted gas heater, knowing how to spot and troubleshoot common issues can save you discomfort, downtime, and expensive service calls.

Here’s a handy guide to help you identify and solve typical HVAC problems faced by households.

Reverse Cycle Air Conditioners: Common Problems and Quick Fixes

Reverse cycle systems are hugely popular because they offer both heating and cooling in one. However, they can run into a few familiar issues:

System Blowing Air But Not Heating or Cooling Properly

• Possible cause: Clogged filters or blocked outdoor units.

• DIY fix: Clean or replace the filters. Check for leaves or debris around the outdoor condenser and clear it carefully.

Strange Noises (Buzzing, Rattling, or Humming)

• Possible cause: Loose screws, debris caught in the fan, or a failing motor.
• DIY fix: Turn off the unit, inspect the outdoor fan for obstructions, and tighten any accessible panels.

Bad Smells from the Vents

• Possible cause: Mould or mildew in the indoor coil.
• DIY fix: Clean the filters and schedule a professional clean if smells persist — mould buildup can be harmful.

Tip: Regular air conditioner servicing (once a year) can prevent most reverse cycle issues before they start.

Evaporative Cooling Systems: Troubleshooting Rooftop Coolers

Evaporative coolers are a great choice in drier climates. But they can suffer if not properly maintained.

Weak or No Airflow

• Possible cause: Faulty water pump or a disconnected fan belt.
• DIY fix: Check the fan belt tension (it should be firm but not overly tight) and inspect the pump if you’re confident. Otherwise, call a technician.

Water Leaks from the Roof Unit

• Possible cause: Cracked water lines or blocked drain outlets.
• DIY fix: Turn off the system and inspect visible hoses and drain lines. If you see splits or significant mineral buildup, replacement is often needed.

Bad Smells When Running

• Possible cause: Stagnant water in the unit or dirty pads.
• DIY fix: Clean the water tank and replace the pads every 12 months — ideally before the hot weather hits.

Tip: Always shut down and fully dry out your evaporative cooler before winter to avoid bacterial growth.

Ducted Gas Heating: Issues and Safety Reminders

Ducted gas heating has long been a staple of homes, although many homeowners are now choosing electric ducted heating options to better align with sustainability goals. Gas is still reliable and fast, but like all gas appliances, requires vigilance for safety and efficiency.

Heater Not Igniting or Staying On

• Possible cause: Faulty ignition systems, dirty burners, or blocked filters.
• DIY fix: Check that your thermostat is set correctly. Clean or replace filters. Beyond that, ignition issues should always be handled by a licensed gas fitter.

Unusual Smells (Especially Gas)

• Possible cause: Gas leak or combustion problems.
• DIY fix: Immediately turn off the heater, open windows, and call a licensed technician. Never ignore the smell of gas.

Weak Heating or Uneven Warmth

• Possible cause: Duct leaks or poor airflow from dirty filters.
• DIY fix: Inspect accessible ducts for damage or disconnections. Replace filters if they haven’t been cleaned in a while.

Tip: For safety, all gas heaters should be checked by a licensed gas fitter every two years.

When to Call the Professionals

While some basic maintenance (like cleaning filters and checking for debris) can be DIY, anything involving gas components, electrical systems, or refrigerant lines should be left to trained HVAC professionals.

Scheduling annual servicing — ideally in spring or autumn — helps spot minor issues before they become expensive problems and keeps your heating and cooling systems running at peak efficiency.

Keeping your home comfortable through wild weather swings isn’t just about good equipment — it’s about smart maintenance, too.