Winter Fault Guide
LG Air Conditioner Not Heating
Few things are more unwelcome on a frosty morning than an LG air conditioner not heating. Reverse cycle systems are clever, yet they have quirks that confuse many owners, especially around defrost and warm start. Below we explain normal winter behaviour, genuine faults, the checks you can make yourself and the point where a licensed technician should take over.
How It Works
How Does an LG Reverse Cycle System Make Heat?
Your LG does not burn anything to warm the room. Instead, it runs the refrigeration cycle backwards. The outdoor coil absorbs heat from the outside air, even on a cold day, and the indoor coil releases that heat into your living space.
A reversing valve inside the outdoor unit switches the direction of refrigerant flow. When you choose heat mode, that valve changes position and the indoor coil becomes the hot side. If the valve, its coil or the controlling board misbehaves, the system may keep cooling while you are asking for warmth.
Understanding this matters, because several winter complaints are really the system doing its job. Others, by contrast, point to real faults in sensors, valves or refrigerant charge.
It also explains why outdoor conditions matter so much in winter. The colder and damper the air outside, the harder the outdoor coil must work to collect heat. At the same time, moisture in that air freezes onto the fins, so the unit must stop now and then to clear it. A healthy LG handles this routine automatically, while a faulty one struggles to keep up.
Normal or Not
Is My LG Actually Faulty, or Just Defrosting?
Before assuming the worst, consider these normal LG behaviours. Each one can make a healthy unit seem broken for a few minutes at a time.
Warm Start Delay
When heating begins, LG units hold the indoor fan back until the coil warms. This avoids a blast of cold air. A short wait after pressing start is expected.
Defrost Cycle
On cold, damp mornings, frost builds on the outdoor coil. The unit pauses heating, melts the frost and then resumes. You may see steam outside and notice the indoor fan stop.
Reduced Output Near Set Point
As the room approaches your chosen temperature, the inverter slows the compressor. Air from the vents then feels mildly warm rather than hot, which is normal.
During defrost, some LG indoor displays show a symbol or indicator. Check your user manual for the exact signal on your model. If heating returns within a reasonable time, the unit is behaving as designed.
Ranked Causes
Why Won’t My LG Heat the Room Properly?
When heating is genuinely poor, the causes fall into a predictable order. The first few are things you can address yourself. The later ones require specialist tools and licences.
Easier Causes
- Remote set to cool, dry, fan or auto instead of heat
- Set temperature lower than the current room temperature
- Dusty filters restricting the flow of warm air
- Outdoor unit buried in leaves, crowded by plants or boxed in
- Timers or ThinQ schedules switching the unit off early
Technician Causes
- Reversing valve stuck or its solenoid coil failed
- Outdoor air or coil sensor reading incorrectly
- Low refrigerant charge caused by a leak
- Outdoor fan motor seized or running slowly
- Inverter board or compressor fault
One telling sign is cold air coming out steadily for a long time in heat mode. That often suggests the reversing valve has not switched. On the other hand, lukewarm air that never gets hot leans more towards low refrigerant or airflow problems.
Do It Yourself, Safely
What Should I Try First When My LG Will Not Heat?
These checks are safe for any owner and cover the usual winter mistakes. Do not open panels, touch refrigerant pipes or attempt electrical work. If you want a general overview first, read our article on a reverse cycle air conditioner not heating.
Look for the Sun Symbol
On most LG remotes, heat mode shows a sun icon. Press the mode button until it appears, then set a temperature well above the room.Give It Time
Wait several minutes after starting. Warm start and the compressor restart delay both slow the first burst of heat.Check for Defrost Outside
Watch the outdoor unit. Steam and dripping water during a pause usually mean defrost is running, so give it a little longer.Clean the Filters
Dusty filters reduce warm airflow and can trigger overheating protection on the indoor coil. Rinse and dry them fully.Reset at the Breaker
Turn the system off, switch off its breaker for a few minutes and then restore power. Try heating again afterwards.Swap the Remote Batteries
Cold weather drains weak batteries faster. Fresh ones make sure the mode change actually reaches the unit.
City by City
Why Do LG Heating Faults Spike in Winter?
Many households use their LG mostly for cooling, so a fault in heat mode may go unnoticed until the first cold snap. Suddenly, everyone in the street switches to heat on the same morning. Regional conditions then add their own complications.
Melbourne and Adelaide Frosts
Clear, cold winter mornings in Melbourne and Adelaide create ideal conditions for frost on outdoor coils. Units defrost more often, and any weakness in sensors or valves shows up quickly. Outer suburbs and foothill areas feel this most.
Sydney Damp Chill
Sydney winters are milder, yet damp air still frosts outdoor coils overnight in western and southern suburbs. Units that ran hard all summer may also carry dirty coils into winter.
Perth and Brisbane Occasional Use
In Perth and Brisbane, heating is used less, so problems lie hidden for months. A unit that worked perfectly last summer can reveal a stuck reversing valve on the first cool evening.
Storms and Power Disruptions
Winter storms bring outages and surges. Afterwards, an LG may show a code or refuse to heat until power stabilises and the board resets.
Coastal Corrosion
Homes near the beach in any of these cities face salt laden air all year. Over time, salt eats into the fins of the outdoor coil and weakens joints. A corroded coil collects less heat in winter and may eventually develop a refrigerant leak, so rinsing and regular servicing matter more on the coast.
Fault Codes
Which LG CH Codes Can Stop Heat Mode?
If your indoor unit flashes CH followed by a number, that code is your most valuable clue. Visit our LG error code guide for the full picture. These codes commonly relate to heating faults.
CH44
Outdoor air sensor fault. LG uses this reading to plan defrost, so heating suffers without it.
CH02
Indoor coil inlet sensor fault. The board cannot guard against the coil overheating in heat mode.
CH61
High temperature protection. On some models it flags the indoor coil running too hot while heating.
CH05
Communication fault between indoor and outdoor units. The system stops rather than run blind.
CH67
Outdoor fan locked or stalled. Without it, the outdoor coil cannot draw heat from the air.
CH38
Low refrigerant detected. Heating capacity drops sharply when the charge is short.
Code definitions can differ between LG model families. Therefore, always quote the full model number when you call, as it helps the technician prepare.
Professional Diagnosis
How Does a Technician Find an LG Heating Fault?
A technician starts by confirming the complaint in heat mode, then works through the system methodically. They separate normal defrost behaviour from a genuine fault before testing individual parts.
- Recording any stored CH codes and the unit’s operating history
- Checking air temperature leaving the indoor unit in heat mode
- Confirming whether the reversing valve actually switches
- Testing the solenoid coil and the board signal that drives it
- Measuring outdoor air and coil sensor readings
- Inspecting the outdoor coil for frost buildup, dirt or corrosion
- Checking outdoor fan speed and motor condition
- Measuring pressures and testing for leaks if capacity is low
- Reviewing defrost timing against expected behaviour
Any refrigerant handling must be carried out by an ARCtick licensed technician. The technicians we send hold the licences their work requires, so leak repair and recharging are handled legally and safely.
Once the cause is clear, the technician talks you through the options. Sometimes that is a simple sensor replacement or a coil clean. Other times, such as with a failed compressor on an older unit, it is worth weighing repair against replacement. Either way, you get the facts before deciding.
LG Ranges
Do Different LG Models Behave Differently in Heat Mode?
LG sells several reverse cycle families in Australia, and their heating behaviour is broadly similar. Even so, small differences in controls and features can change what you notice on a cold day.
Dualcool Wall Splits
Dualcool is the core LG wall split range. Its dual inverter compressor varies speed smoothly, so heat output rises and falls gradually rather than in bursts.
Artcool Designer Splits
Artcool units share the same core technology behind a decorative mirror or flat panel. Because the front is solid, filters and airflow paths deserve extra attention during cleaning.
Ducted and Multi Split
LG ducted and multi split systems serve several rooms from one outdoor unit. When one indoor head heats and another cools, the system may lock out the conflicting request.
Many recent LG models connect to the ThinQ app over home wifi. That app lets you switch to heat before you get home, yet it also means settings can change without anyone touching the remote. Always check the app when heating behaves unexpectedly.
Before Winter
How Can I Prepare My LG for the Cold Months?
A short autumn routine catches most heating faults before you actually need warmth. It takes little time and no tools. Moreover, it gives you a chance to book a technician before the winter rush.
- Run heat mode for a short while on a mild autumn day
- Wash filters that collected dust and pollen over summer
- Clear fallen leaves from around and on top of the outdoor unit
- Make sure the outdoor unit drains freely so defrost water can escape
- Check the remote shows the sun symbol and responds normally
- Book a service if heating feels weaker than it did last winter
If your outdoor unit sits in a low spot where cold air pools, defrost cycles may be more frequent. That is not a fault, although a technician can advise whether the placement is causing trouble.
Ducted Systems
What If My LG Ducted System Is the One Not Heating?
LG ducted systems heat the same way as wall splits, but they add zones, ducts and a wall controller. As a result, there are a few extra places to look when warm air disappears.
First, check the wall controller shows heat mode and that the relevant zones are switched on. A closed zone damper means no air reaches that room. Next, look at the return air grille, usually in a hallway ceiling, as its filter can clog just like a split system filter.
If only some rooms are cold, a collapsed or disconnected duct in the roof may be to blame. That needs a technician, because roof spaces carry fall and heat risks. If every room is cold, the fault is more likely in the outdoor unit or refrigerant circuit.
Running It Anyway
Can I Keep Using My LG While It Is Not Heating?
Running an LG through normal defrost is perfectly fine. However, continued use with a real fault can make things worse. A system low on refrigerant works harder, and an outdoor fan that will not spin lets ice build up thickly on the coil.
Switch off and seek help if you notice repeated CH codes, a thick sheet of ice outdoors that never clears, burning smells or a tripping breaker. Otherwise, it is reasonable to keep using the unit gently while you wait for a booking.
Open more detail
Thick ice outside. A little frost is normal. A solid block of ice, particularly around the base, suggests defrost is failing or the drain pan heater on some models is not working.
Unit cools instead of heats. Cold air for a long time in heat mode commonly points to the reversing valve. Leave it off and book a check.
Unit shuts down repeatedly. Our article on an air conditioner that keeps turning off explains common protection trips.
Indoor fan stays still. If warm start never finishes, the fan or its sensor may be faulty. See our guide to an AC fan not working.
Book a Repair
Who Can Repair an LG Heating Fault Near Me?
We take bookings for LG heating faults across five major cities and pass them to licensed technicians close to you. Pick your city for local repair details, or explore more symptoms in our AC troubleshooting section.
For brand specific information by location, try our pages for Sydney LG owners, Brisbane LG owners, Perth LG owners or Adelaide LG owners. Melbourne owners can visit our LG servicing page. Our air conditioning service Australia homepage explains how bookings work.
Questions
Frequently Asked Questions
Why does my LG blow cold air in heat mode?
Briefly, it may be defrosting or warming up. If cold air continues for a long time, the reversing valve or its control may have failed, and a technician should check it.
How often should an LG defrost in winter?
It depends on outdoor temperature and humidity. On cold, damp mornings it may defrost fairly often. On dry or milder days, it may hardly defrost at all.
Is steam from the outdoor unit a problem?
No. Steam during defrost is simply frost melting off a warm coil. It looks alarming, yet it is a sign the system is working correctly.
Why is my LG heating weakly on very cold mornings?
Heat pumps lose some capacity as outdoor temperatures fall. Frequent defrosting also interrupts output. Weak heating on the coldest mornings can be normal, but steady poor heating is not.
Can low refrigerant stop my LG heating?
Yes. A low charge reduces heating just as it reduces cooling. The leak needs finding and repairing by a licensed technician before recharging.
Should I use the LG in auto mode in winter?
Auto mode works, but for troubleshooting choose heat mode directly. That way you know exactly what the system has been asked to do.
My LG heats fine but cooling is weak. Is that related?
Possibly, as some faults affect both modes. Our guide on an LG not cooling covers the cooling side in detail.
More Help
Other LG Problems We Explain
Explore these guides if your LG has other symptoms, or simply send us a message.
Cold House and an LG That Will Not Warm Up?
Tell us the model and any code on the display. We will arrange a licensed technician to restore your heating.
Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles