Inverter Heat Sink Overheat
LG CH62 Error Code
The LG CH62 error code is raised when the heat sink on the outdoor inverter board gets too hot. That heat sink cools the power electronics that drive your compressor, so LG shuts the system down before those parts are damaged. This guide explains what pushes heat sink temperatures up and how the fault is fixed.
Plain Words
What Is the LG CH62 Code Telling Me?
The outdoor unit of an LG inverter system contains a circuit board that converts mains power into the variable supply that drives the compressor. The main power parts on that board, including the power module, produce a lot of heat as they switch current. To carry that heat away, they are bolted to a finned aluminium block called a heat sink.
The heat sink usually sits in the path of the outdoor fan’s airflow, so moving air cools it. A temperature sensor monitors it. When the reading passes a protection limit, the board stops the compressor and shows CH62. LG service information describes it as the outdoor unit inverter compressor PCB heat sink temperature being too high.
CH62 is a protection code, not a sensor code. It means the heat sink really is getting hot, or the board believes it is. Either way, the power electronics are at risk if the system keeps running.
It sits close to CH61 in meaning. CH61 is about the refrigerant coil getting too hot. CH62 is about the electronics getting too hot. They often share causes, but they protect different parts.
The Parts
Which Components Are Involved in CH62?
A heat sink can only shed heat if several things are working together. When one of them falls short, temperatures climb.
The Heat Sink and Its Fins
The fins must be clean and open so air can flow through them. Dust, insects and debris packed into the fins act like insulation.
Thermal Contact
A thin layer of thermal compound helps heat pass from the power module into the heat sink. If that layer dries out or the mounting loosens, heat stays trapped in the module.
The Outdoor Fan
The same fan that cools the condenser also pulls air across the heat sink. A weak or stopped fan quickly lets the heat sink overheat.
The Power Module
A power module that is starting to fail can produce extra heat even under normal load. That shows up as a rising heat sink temperature.
Compressor load matters too. Anything that makes the compressor work harder, such as high condensing pressure, makes the power module pass more current and produce more heat.
Recognising It
How Will I Notice CH62 on My LG?
The indoor unit shows CH and 62, or a blinking light pattern on models without a numeric display. Ducted systems show it on the controller.
Like CH61, CH62 often appears under heavy load. Owners tend to see it on hot afternoons, when the system has been running hard for hours. It may also appear after the system has been asked to cool down a very hot home quickly, which keeps the compressor at high speed for a long time.
Before the code appears, some LG systems reduce compressor speed to keep the heat sink below its limit. You may notice cooling getting weaker in the heat of the day without any code at first. If conditions do not improve, the protection then steps in fully and CH62 appears.
Open more detail
CH62 should not be confused with CH65. On many LG models, CH65 means the heat sink sensor itself is open or short circuited. CH62 means the heat sink temperature reading is too high. The first is usually a sensor repair, while the second is about why the heat sink is getting hot. Some third party lists blur the two, so the technician will confirm the meaning for your model.
Ranked Causes
What Causes the LG Heat Sink to Overheat?
The causes run from simple airflow problems to failing electronic parts. Airflow issues are by far the usual.
Airflow and Load
- An outdoor unit crowded by walls, fences, plants or stored items
- Hot exhaust air recirculating in a tight space
- A dirty condenser coil raising compressor load
- Direct afternoon sun heating the outdoor unit casing
Internal Faults
- Dust, insects or nests clogging the heat sink fins
- A slow or failed outdoor fan motor
- Dried thermal compound or a loose power module mounting
- A failing power module or a faulty heat sink sensor
Insects are a surprisingly common factor. Ants, wasps and other insects are drawn to the warmth of the electronics compartment. Nests built in or around the heat sink can block airflow completely. In some areas, ants also cause electrical faults by bridging contacts on the board.
Owner Checks
What Can I Safely Check When CH62 Shows?
The heat sink and inverter board sit behind sealed covers. They carry high voltage and can stay charged after the power is switched off. Your checks must stay on the outside.
- Photograph the code and note the outdoor temperature and how long the system had been running.
- Switch the system off with the remote, then at the breaker or outdoor isolator.
- Clear anything crowding the outdoor unit, including bins, pot plants, timber and outdoor furniture.
- Remove leaves and debris from around the coil and fan grille by hand.
- Watch for wasps or ants around the outdoor unit. If you see a nest, stay clear and mention it when booking.
- Let the unit cool for at least half an hour before restoring power.
- When you restart, choose a moderate set point to reduce the load.
If CH62 returns soon after restarting, or on mild days, switch off and book a technician. That suggests an internal problem rather than just a hot day.
Keep Running
Is It Safe to Keep Using My LG With CH62?
The heat sink protection is there to prevent damage to some of the most sensitive and expensive parts in the outdoor unit. Power modules can fail permanently if they overheat, and a failed module often means a new board.
One trip on an extreme day, which clears after the area around the unit is tidied and the unit has cooled, is not cause for alarm. Repeated trips are different. Each overheating event adds stress to the power module and the solder joints that hold it to the board.
If CH62 keeps returning, switch off at the breaker and book a technician. A quick airflow or cleaning fix now is far better than a board replacement later.
Diagnosis
How Does a Technician Repair an LG CH62 Fault?
The technician needs to find out whether the heat sink is genuinely overheating and, if so, why. The process looks like this.
Review the Pattern
They ask when the code appears, whether it happens only in extreme heat or also on mild days, and how the system performed beforehand.Assess Location and Airflow
The site is checked for clearance, recirculation, sun exposure and anything that stops hot air escaping.Check the Outdoor Fan
Fan speed and motor condition are checked under load. A slow fan starves both the heat sink and the condenser.Isolate and Inspect
After isolating power and allowing the board to discharge, the technician opens the electrical compartment and inspects the heat sink fins for blockage.Check Thermal Contact
Mounting screws and thermal compound between the power module and heat sink are inspected. Dry compound or loose mounting is corrected.Test the Sensor
The heat sink sensor reading is compared with an independent measurement to rule out a false high reading.Check Load and Pressures
Condenser condition and operating pressures are checked, since high load raises module heat.Repair and Monitor
Once fixed, the system is run under load while heat sink temperature is monitored to confirm it stays within limits.
Inside the Electronics
Why Do Inverter Boards Get So Hot?
An inverter controls compressor speed by switching current on and off at very high speed. Each switching event wastes a little energy as heat. Thousands of switches every second add up to a meaningful amount of heat, concentrated in a small module.
The higher the compressor speed and load, the more current the module handles and the more heat it produces. On a hot day, with the compressor at full speed and the surrounding air already hot, the heat sink has less temperature difference to work with. It relies on airflow to keep up.
This is why CH62 is so closely tied to both weather and airflow. A healthy system with good clearance and a clean heat sink copes with extreme days. A system with a blocked heat sink, a weak fan or a cramped location runs out of margin when it matters most.
It also explains why a failing module can trigger CH62 even on mild days. A module that is deteriorating inside wastes more energy as heat for the same output. When the heat sink temperature rises without an obvious airflow cause, the module itself becomes a suspect.
Climate
How Do Australian Conditions Contribute to CH62?
Heat is the obvious factor. Extended heatwaves push outdoor units to their design limits for days at a time. Units in full western sun, on dark roofs, or surrounded by heat reflecting paving face even higher temperatures around the casing.
Dust is another. In dry, windy conditions, fine dust is drawn into the outdoor unit and settles on the heat sink fins. Over time it builds into a felt like layer that blocks airflow. Bushfire seasons can add ash and soot to the mix.
Insects thrive in warm climates and seek shelter in warm, dry places. The electronics compartment of an outdoor unit is ideal. Ant nests and wasp nests in or near the heat sink are common finds during CH62 repairs in many parts of the country.
Coastal salt adds corrosion, which can affect the fins and the fan motor. Storms can also leave debris blocking the outdoor unit, and power disturbances can stress a module that is already running hot.
Prevention
How Can I Help Prevent CH62?
Keeping the outdoor unit cool and clean protects the inverter electronics as well as the condenser.
Keep Clearance
Maintain open space around the outdoor unit, especially in front of the fan, so hot air can escape and cool air can enter.
Service Before Summer
A pre summer service can include a coil clean and a check of the fan and electronics compartment for dust and pests.
Use Moderate Settings
Very low set points in extreme heat keep the compressor at full speed for longer. A moderate setting reduces load on the inverter.
Pre cooling the home in the morning, before the hottest part of the day, can also help. It lets the system reach comfort at lower load instead of fighting peak afternoon heat.
Two Paths
Is My CH62 an Airflow Problem or a Board Problem?
Many owners want to know whether CH62 is a simple fix or an expensive one. The pattern of the code gives strong hints.
Pointing to Airflow or Load
The code appears only on very hot afternoons, after long running. It clears when the evening cools. The outdoor unit is cramped, dusty or in strong sun. A clean and better clearance often solve it.
Pointing to Internal Faults
The code appears on mild days, soon after starting, or keeps returning even after the area is cleared. The outdoor fan may sound weak. A fan, thermal contact, sensor or module problem is more likely.
Either way, the technician will confirm the cause with testing. Sharing what you observed helps them get there faster.
What Should I Tell You When I Book?
Mention when the code appears, the outdoor temperature at the time, how long the system had run, and where the outdoor unit is located. Let us know about any insect activity around the unit, and whether the outdoor fan seems to be spinning normally when you look from a safe distance. A photo of the outdoor unit and its surroundings is very helpful.
If the system is still within its warranty period, check your paperwork first. Board level faults on newer units may need to go through the manufacturer’s own service network. For older systems, a clear diagnosis lets you weigh up a repair against other options with real information.
Related Codes
Which LG Codes Are Linked to CH62?
These sibling codes often share causes with CH62 or appear in the same circumstances.
LG CH61
Outdoor condenser coil running too hot.
LG CH67
Outdoor fan motor lock, a direct cause of poor cooling airflow.
LG CH21
A DC peak current trip in the same inverter circuit.
CH65, the heat sink sensor fault, is another close relative. See all covered codes on the LG error code hub, or browse the error code library.
Getting a Technician Out
Can You Send a Technician for CH62 in My City?
Yes. We arrange licensed technicians for LG inverter overheating faults across Sydney, Melbourne, Brisbane, Perth and Adelaide.
For brand information, see our LG air conditioning page or the local pages for LG Sydney, LG Brisbane, LG Perth and LG Adelaide. Rapid Air Cooling is a booking service, not affiliated with LG. The technicians we send hold the licences their work requires.
Questions
Frequently Asked Questions
What is a heat sink on an air conditioner?
It is a finned aluminium block attached to the power electronics on the outdoor board. It draws heat away from those parts so they do not overheat.
Is CH62 the same as CH61?
No. CH61 is about the refrigerant coil running too hot. CH62 is about the inverter electronics running too hot. They often share airflow causes.
Can insects really cause CH62?
Yes. Ants and wasps often nest in warm electronics compartments and can block heat sink fins. Keep clear of any nest and let a technician deal with it.
Why does CH62 appear on mild days too?
That suggests an internal issue, such as a weak outdoor fan, dried thermal compound, a faulty sensor or a failing power module, rather than just hot weather.
Will a board replacement be needed?
Not always. Many CH62 faults are fixed by cleaning, restoring airflow or correcting thermal contact. A board is only replaced when testing shows the module has failed.
Does pre cooling help prevent CH62?
It can. Cooling the home earlier in the day lets the system reach comfort before peak heat, reducing load on the inverter in the afternoon.
Where can I learn more?
Our troubleshooting guide covers common issues, and our page on air conditioning service Australia explains how we arrange visits.
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LG Showing CH62?
Switch the system off, clear the area around the outdoor unit and give us a call. We will arrange a licensed technician to find out why the inverter is running hot.
Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles