If your air con is not heating properly in winter but works fine in summer, it’s usually one of two things: a simple setting or airflow issue, or a fault that needs proper diagnosis.
In Brisbane, reverse cycle air conditioning often sits unused for months. When the first cold mornings hit, homeowners switch it over and expect instant warm air. Sometimes it takes a few minutes. Sometimes nothing happens at all.
Here’s what to check first, what you can fix quickly, and when it’s time to book air con repairs.
Start With The Basics: Mode, Temperature & Fan
This sounds obvious, but it’s one of the most common causes we see.
Make sure the system is set to heat mode, usually shown by a sun symbol. Auto mode can be unreliable when the room temperature sits close to your set point, especially during mild Brisbane winters.
Set the temperature a few degrees above the current room temperature. Around 24–26°C is a good starting point for heating. If the fan is set too low, the room may warm slowly. Auto fan is usually best for steady comfort.
Give the system a few minutes. Reverse cycle air conditioners don’t always blow warm air the second they start.
Dirty Filters Are Blocking Warm Airflow
If the air coming out feels weak, check the filters.
Dusty filters restrict airflow, which makes it harder for the indoor unit to move warm air through the room. The system may still be running, but it won’t feel like it is doing much.
For a split system, remove and clean the filters if they’re clogged. For ducted air con, check return air grilles and make sure they aren’t covered by furniture, boxes or built-up dust.
If the airflow is still poor after cleaning, the system may need professional servicing or air con repairs.
The Outdoor Unit Is Struggling
Your outdoor unit still does important work in heating mode. If it’s blocked by leaves, dirt, garden growth or poor ventilation, heating performance can drop quickly.
Check that the outdoor unit has clear space around it. Don’t hose internal electrical areas or pull panels apart. A simple visual check is enough.
On colder mornings, some systems may also pause briefly while they manage outdoor coil conditions. That can be normal. Long delays, constant stopping, loud noises or repeated fault lights are not.
Ducted Air Con Zone Problems
If your ducted system is heating some rooms but not others, the issue may not be the main unit.
If one area never heats properly, even with the right settings, it’s worth getting the ducts, dampers and controls checked. This is especially common when homeowners think the whole air con is not heating, but the issue is actually with zoning or airflow.
Refridgerant, Sensor Or Electrical Faults
If the system runs but never produces warm air, the problem may be inside the unit.
Common causes can include:
- Refrigerant leaks
- Faulty sensors
- PCB faults
- Fan motor issues
- Compressor faults
- Electrical supply problems
These aren’t DIY fixes. Running the system while it’s faulting can create more damage and lead to a bigger repair bill.
Stop using the unit and call for help if you notice:
- Burning smells
- Tripping breakers
- Grinding noises
- Water leaks
- Flashing error codes
- The system turning itself off
When To Book A Repair
If you’ve checked the settings, cleaned the filters and cleared the outdoor unit but your air con is not heating properly, book a professional inspection.
LCM Air Conditioning handles residential air con repairs, servicing and fault diagnosis across Brisbane. Our technicians can check the system properly, explain what’s wrong, and recommend the fastest practical fix.
Don’t wait through cold mornings with a system that’s not doing its job. Call LCM Air Conditioning on 1300 526 247 or book a repair today.