Mac heat and fan — overheating, noise and constant fan
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Quick answer
Heat and noisy fans on a Mac almost always have one of three causes: dust in the cooling system, dried-out thermal paste, or a background process pegging the CPU at 100%. A MACMO 'tune-up' (cleaning + new thermal paste) at DKK 800-1,500 solves most hardware causes and typically gives the Mac an extra 3-5 years of life.
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Why is my Mac getting hot?
Three main causes: 1) software stressing the CPU/GPU — check Activity Monitor → Energy for heavy users. 2) Dust has blocked airflow — needs physical cleaning. 3) Thermal paste has dried out — after 4-5 years. The MacBook Air and Pro 13-inch Touch Bar run hotter than newer models by design.
Why is the fan noisy?
A loud fan means the cooling system can't keep the temperature down at normal speed. In 70% of cases: dust in the fan and heatsink. We clean the cooling system and replace thermal paste for DKK 800-1,500 — typically 60-90 minutes of work.
Why is the fan running constantly?
Constant fan at idle is caused by: 1) a process using CPU (check Activity Monitor), 2) thermal throttling (kernel_task uses CPU to lower performance), 3) sensor faults (the SMC thinks the Mac is hot when it isn't). An SMC reset can solve the latter on Intel Macs.
Why does my Mac get hot at idle?
Check Activity Monitor for hidden processes: mds_stores (Spotlight indexing), photoanalysisd (Photos analysing), softwareupdated (downloading an update), iCloud syncing. These can run for hours. If no visible processes are active, it's hardware (typically dried-out thermal paste).
Why does my MacBook get hot when charging?
Charging generates heat (chemical reaction in the battery plus electrical resistance in the charging circuit). Up to ~40°C is normal during full charging. If it gets significantly hotter, or the heat concentrates in one spot, either the battery is starting to swell or the charging circuit is faulty — contact us.
Why does my MacBook get hot in sleep?
In sleep, the Mac should be cool. If it gets warm: 1) Power Nap is enabled (fetching mail, running backup) — turn it off. 2) An app is keeping the Mac partly awake. 3) A faulty SMC not managing sleep state correctly. SMC reset on Intel; on Apple Silicon it's typically an app abusing the 'Prevent Sleep' API.
Why won't the fan cool things down?
If the fan is running flat out but temperatures don't drop, the cooling system is compromised: 1) blocked vents (dust), 2) dried-out thermal paste between CPU/GPU and heatsink, 3) a failing heatpipe. All three require opening the MacBook. We solve it with a standard tune-up.