Aircon Not Turning On? 7 Things to Check Before Calling a Technician

🔌❄️ From dead batteries to tripped breakers—systematically diagnose why your air conditioner won’t start

You press the power button on your remote. Nothing happens. You press again. Nothing. You walk up to the aircon and press the manual button (if it has one). Still nothing. No display. No beep. No fan. No sound at all.

Your heart sinks. “Is my aircon dead? Do I need a new one? How much is this going to cost?”

I’ve been there. And after helping hundreds of people with aircon not turning on problems, I’ve learned that 80% of cases have simple, DIY fixes that take less than 5 minutes and cost nothing.

Dead remote batteries. A tripped breaker. An isolator switch that someone accidentally turned off. A timer setting you forgot about. These are the real culprits most of the time.

In this guide, I’ll walk you through 7 things to check when your air conditioner won’t start. Follow them in order—each step eliminates a possible cause. By the end, you’ll either have a working aircon or a clear diagnosis to give to a technician.

For more troubleshooting help, check same-day aircon repair services and load-shedding troubleshooting guide. Ready to diagnose? Let’s go.

🔍 Quick Diagnostic: Is It the Remote or the Aircon?

Before diving into detailed checks, use this flowchart to narrow down the problem:

🔋 Check #1: Remote Control Batteries (The #1 Culprit!)

This is the most common reason for aircon not turning on. The aircon is fine—the remote is just dead.

How to check:

• Look at the remote display. Is it blank, dim, or flickering?
• Do the smartphone camera test (see above). No flashing light = dead batteries.
• Can’t remember the last time you changed batteries (likely over a year ago).

DIY fix (2 minutes):

1. Open the battery compartment on the back of the remote
2. Remove old batteries (dispose properly—batteries are hazardous waste)
3. Check for corrosion (white/green crusty residue)—clean with dry toothbrush if present
4. Install fresh, high-quality alkaline batteries (not “heavy duty”)
5. Ensure correct polarity (+ and – match the diagram)
6. Test the remote—point at aircon and press power

📱 Check #2: Remote Display and Settings

Sometimes the remote works (display is on, batteries are good) but the aircon won’t respond because of a setting issue.

How to check:

• Remote display shows numbers and icons clearly
• Smartphone camera test shows flashing light
• But aircon still doesn’t respond

Possible issues:

• Child lock is on: Look for a padlock icon on the display. Press and hold the “Mode” or “Set” button for 5-10 seconds to unlock.
• Remote is in wrong mode: Some remotes have a “Heat/Cool” toggle. Ensure it’s set to Cool (snowflake icon).
• Timer is active: The aircon may be waiting for a timer to start. Press the “Timer” or “Cancel” button to clear.
• Remote is for a different unit: If you have multiple aircons, you might be using the wrong remote.

DIY fix: Clear all timer settings, unlock child lock, and ensure the remote is in Cool mode. If still not working, proceed to power checks.

⚡ Check #3: Power Supply (Breaker and Isolator Switch)

If your remote is working but the aircon is completely dead (no lights, no display, no sound), the problem is almost certainly a power supply issue.

How to check:

1. Go to your electrical distribution board (fuse box)
2. Look for a breaker labeled “Aircon,” “HVAC,” “Outdoor Unit,” or similar
3. Is the breaker in the “off” position or halfway between on and off? (tripped)
4. Go outside to the outdoor compressor unit
5. Find the isolator switch (a small grey/white box near the outdoor unit, usually with a red or yellow switch)
6. Is the isolator switch in the “off” position? (sometimes accidentally turned off by gardeners, children, or during maintenance)

DIY fixes (1 minute):

1. For a tripped breaker: Flip the breaker fully to “off,” wait 10 seconds, then flip back to “on.”
2. For an isolator switch off: Flip the switch to the “on” position (usually up or marked with a green indicator).
3. After restoring power, wait 2-3 minutes for the aircon’s internal electronics to initialise, then try the remote again.

Read our circuit breaker and fuse box guide and prepaid meter guide.

⏰ Check #4: Timer or Sleep Mode Settings

Many aircons have timers that can turn the unit off (or on) at specific times. You might have set a timer and forgotten about it.

How to check:

• Look at your remote display for timer icons (clock symbol, “TIMER ON/OFF,” or “SLEEP”)
• If you see a timer icon, the aircon may be waiting for a scheduled start time
• Some units have a “sleep mode” that turns the unit off after a set number of hours

DIY fix:

1. Press the “Timer” or “Cancel” button on your remote (sometimes you need to press it multiple times to clear)
2. Press and hold the “Cancel” or “Clear” button for 3-5 seconds
3. Remove batteries from the remote for 30 seconds (this clears some timer memories)
4. Try turning the aircon on again

🌡️ Check #5: Thermal Overload Protection Tripped

The compressor has a built-in thermal overload switch that shuts it off if it gets too hot. This can prevent the aircon from starting until it cools down.

How to check:

• The aircon was running earlier but now won’t start
• The outdoor unit feels very hot to the touch
• There was a recent heatwave or the unit was running for many hours
• The outdoor unit is in direct sunlight or has poor airflow (blocked by bushes, walls, debris)

DIY fix:

1. Turn off the aircon at the breaker (not just the remote)
2. Wait 30-60 minutes for the compressor to cool completely
3. Ensure the outdoor unit has at least 300mm clearance on all sides
4. Clean any debris from around the outdoor unit
5. Restore power and try starting the aircon
6. If it works, the thermal overload has reset—but investigate why it tripped (dirty coils, failing fan motor, poor airflow)

🔌 Check #6: Blown Fuse or Internal Fuse

Some aircons have internal fuses on the control board that can blow during power surges. Window units often have a fuse in the plug.

How to check:

• You’ve checked the breaker and isolator—both are on
• The aircon still has no power (no lights, no display, no sound)
• There was a recent power surge or lightning strike
• For window units: check the plug for a small fuse compartment

DIY fix (for window units only):

1. Unplug the window unit from the wall
2. Look for a small compartment on the plug (may require a small screwdriver to open)
3. Remove the fuse and inspect—if the wire inside is broken, it’s blown
4. Replace with the exact same type and rating fuse (available at hardware stores, R20-R50)

For split systems: Internal fuses are on the control board (PCB) and require professional diagnosis. Do not attempt to open the unit yourself.

Read our PCB board problems guide.

💻 Check #7: Faulty Control Board or Transformer

If you’ve checked everything above and your air conditioner won’t start, the problem is likely a failed internal component.

How to diagnose (requires professional):

• Breaker and isolator are on (power is reaching the unit)
• Remote is working (smartphone camera test passes)
• No lights or display on the indoor unit (not even a standby light)
• The unit is completely dead

Possible failures:

• Failed transformer: Steps down voltage for the control board. No transformer = no power to electronics.
• Failed control board (PCB): The “brain” of the aircon has failed. The unit won’t respond to any commands.
• Blown internal fuse on PCB: Often caused by power surges.
• Failed capacitor: Sometimes prevents the unit from starting (though usually the fan still runs).

Is this DIY? NO. Control board diagnosis and replacement requires specialized knowledge and tools. Call a professional.

Professional fix: A technician will test the transformer, control board, and capacitors. Control board replacement: R1,500-R4,000. Transformer replacement: R500-R1,500.

Read our PCB board problems guide and capacitor failure guide.

🔦 Special Case: Aircon Not Working After Load-Shedding

Load-shedding is a common cause of aircon not turning on in South Africa. Here’s what happens and what to do:

What happens during load-shedding:

• Power is cut to your home (outage)
• When power returns, there’s often a voltage surge (spike)
• The surge can trip breakers, blow fuses, or damage sensitive electronics

What to check after load-shedding:

1. Check the breaker: Power surges often trip the aircon breaker. Reset if tripped.
2. Check the isolator switch: Some switches trip during surges. Flip off then on.
3. Wait for stabilisation: After power returns, wait 5-10 minutes before trying to start the aircon (voltage may fluctuate).
4. Check remote batteries: Some remotes lose their memory after extended power loss.
5. Reset the aircon: Turn off the breaker for 5 minutes, then turn back on (this resets the control board).

If still not working: The power surge may have damaged the control board, capacitor, or transformer. Call a professional.

Read our complete load-shedding troubleshooting guide and backup power guide.

📞 When to Call a Professional (Don’t DIY These)

After trying the DIY checks above, if your air conditioner won’t start, call a professional. Also call immediately if you experience any of these:

How to find a reliable technician: Use our contractor selection guide. Request quotes from local repair technicians and compare prices. Emergency services available for urgent issues.

💰 Repair Cost Guide by Cause (What You’ll Actually Pay)

Here’s what you can expect to pay for professional repairs when your air conditioner won’t start:

For accurate quotes, request quotes from local technicians.

❓ Frequently Asked Questions About Aircon Not Turning On

✅ Final Thoughts: Diagnose Before You Panic

When your aircon is not turning on, it’s easy to panic and assume the worst. But most causes are simple and cheap to fix—or even free.

Key takeaways for “aircon not turning on” troubleshooting:

• Start with the remote: Dead batteries are the #1 cause. Use the smartphone camera test to confirm.
• Check power supply: Tripped breakers and turned-off isolator switches are common and free to fix.
• Check timer and child lock settings: These are easy to overlook and easy to clear.
• Thermal overload is a waiting game: If the compressor is hot, wait 30-60 minutes for it to cool.
• Load-shedding causes unique problems: Power surges can trip breakers or damage components. Check breaker first.
• Don’t ignore burning smells or repeated breaker trips: These indicate serious electrical problems—call a professional immediately.
• Professional diagnosis is worth it: A technician can quickly identify a failed capacitor, control board, or compressor.

Your action plan: First, check remote batteries using the smartphone camera test. Second, check your breaker box and isolator switch. Third, check for timer or child lock settings. Fourth, if the compressor feels hot, wait 30-60 minutes. Fifth, if still not working, request quotes from local repair technicians. For emergencies (burning smell, repeated breaker trips), use our emergency services.