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Your MacBook gets so hot that you can no longer rest your hands on it, the fan blows like a hairdryer, or the machine even shuts down on its own. It's unpleasant, and above all it's bad for the lifespan of your computer.
Here are the 5 most common causes I see in my workshop in Le Cannet, and how to fix them. Spoiler: in 80% of cases, it's just dust in the fans.
When is it normal for a MacBook to run hot?
First of all, let's set a benchmark: a MacBook that warms up slightly and spins up its fan in certain situations is normal:
- A long Zoom/Teams video call
- Exporting video in iMovie or Final Cut
- Compiling code, running a virtual machine
- Playing a video game
- The first macOS update after installation (indexing, optimisation)
What is not normal: your MacBook heating up just from reading an email, browsing 3 tabs, or watching Netflix. If that's your case, let's hunt for the culprit among the 5 causes below.
1. Background processes maxing out the CPU
Typical scenario: a program has crashed or is stuck spinning in a loop. It uses 100% of the processor without you seeing it.
How to check: open the Activity Monitor(Spotlight Cmd+Space → type "activity"). CPU tab. If you see a program at 100% while you aren't actively using it, that's the one. Right-click → Quit.
Common culprits: WindowServer (the display system struggling), kernel_task (the system that manages heat, paradoxically), Adobe Photoshop or Lightroom in the background, Spotlight re-indexing (normal after an update, wait 1-2 h), a third-party antivirus scanning on a loop.
Tip: if you don't recognise a process name, paste it into Google. You'll know within 30 seconds whether it's legitimate or not. Often, these are old uninstalled programs that have left an agent lingering behind.
2. Clogged fans (the No. 1 cause on Macs 4+ years old)
This is the cause I deal with most often in my workshop in Le Cannet. MacBooks draw air in from the bottom and expel it near the hinge. Over the years, dust builds up on the heatsink fins. After 3-5 years, the fans no longer cool effectively.
Typical symptoms: the fan blowing hard as soon as you open the browser, the MacBook very hot on top, a sudden drop in performance after a few minutes (the system reduces the processor speed to avoid overheating — this is "throttling").
Solution: full disassembly and cleaning. This is a workshop job of 1-2 h:
- Removing the bottom case (Apple's special pentalobe screws)
- Cleaning the fans and heatsinks with compressed air + a fine brush
- Checking the condition of the thermal pads
- Often: replacing the thermal paste (see the next cause)
- Reassembly and testing under full load
Expect €70-100 in the workshop. Immediate effect: a silent MacBook, normal temperatures, performance restored. Many of my clients think they have to buy a new machine — a clean-up is enough.
3. Dried-out thermal paste
Thermal paste is a thin layer between the processor and the heatsink that ensures the transfer of heat. Over the years, it dries out and loses its effectiveness.
Symptoms: similar to cause 2 (clogging), plus a high temperature even at idle. The two problems often go together.
Solution: replacing the thermal paste. It's rarely done on its own — we make the most of having it apart for the cleaning anyway. I include it as standard in the clean-ups of Macs more than 4 years old, for ~€10 of quality paste (Arctic MX-4 or Thermal Grizzly).
4. Poor positioning
A simple but underrated case. If you use your MacBook resting directly on:
- A bed or a sofa (the fabric blocks the vents
- A duvet (same thing)
- A cushion on your lap
...you block the air vents on the bottom. The MacBook suffocates and overheats.
Solution: use a rigid stand. A wooden board will do, or a tray, or a dedicated stand (Roost Stand, Twelve South Curve). Placed on a hard surface, your MacBook breathes and stays cool.
Real case: a client in Mougins, a MacBook Pro that was constantly overheating and shutting down. I visited at home: he was working remotely in his bed, on a thick duvet. Moving to a desk with a stand: problem solved instantly, with no repair needed.
5. macOS running slow after an update
The newer versions of macOS (Sonoma, Sequoia recently) have weighed down quite a few older machines. More background processes, more system agents, more AI features.
On Intel Macs from before 2018, these newer versions can cause excessive heat simply because the system is too demanding for the hardware.
Solutions:
- System optimisation: disabling heavy features (visual effects, Spotlight indexing of external sources, excessive iCloud agents).
- Uninstalling heavy background programs: Adobe Creative Cloud agent, Microsoft AutoUpdate, Java, etc.
- For old Macs (before 2014): consider downgrading to a lighter macOS version (Big Sur or Catalina). A security/performance trade-off, to be discussed case by case.
Action plan for your situation
If your Mac is less than 3 years old: probably cause 1, 4 or 5.
- Check the Activity Monitor (free, 5 min)
- Test on a hard surface (free, instant)
- If still hot after an update: system optimisation
If your Mac is more than 3 years old: most likely cause 2 or 3.
- Do the checks above first (just in case)
- If nothing helps: full fan cleaning + thermal paste replacement in the workshop
- Expect €70-100 for 1-2 h in the workshop, MacBook returned silent
MacBook overheating in Le Cannet, Cannes or Mougins? Free diagnosis in the workshop. If it's just the fans, the job takes 1-2 h. Expect €70-100 all in (thermal paste included). 3-month warranty on the work. See the repair service or the Mac service in Mougins.