Thermal Setup

Run this first

Without intervention, the MacBook Air 2020 CPU can sustain 97–100°C at near-idle fan speeds on CachyOS. This is not a minor issue — it risks hardware damage over time. Run 01-thermal-setup.sh immediately after installing.

Why This Happens

The default thermald configuration expects the fan to be at the traditional applesmc platform sysfs path. On the MacBook Air 2020 running kernel 6.19.x-cachyos, the fan is instead exposed via the ACPI APP0001:00 device:

/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:1c/APP0001:00/

thermald cannot find the fan at its expected path, so the fan stays near minimum speed (~2700 RPM) regardless of CPU temperature.

The Fix: mbpfan

mbpfan reads Apple SMC sensors directly via coretemp and drives the fan independently of thermald. The 01-thermal-setup.sh script:

1. Installs mbpfan via your AUR helper
2. Writes /etc/mbpfan.conf with the correct fan curve for this hardware
3. Writes /etc/thermald/thermal-conf.xml to restrict thermald to Intel RAPL power capping only (no fan control)
4. Enables and starts mbpfan.service

Running the Script

This repository handles everything automatically through the interactive installer (make install), but if you want to run it manually:

# Install as your normal user first (AUR helpers cannot run as root)
paru -S mbpfan

# Then run the setup script
sudo bash scripts/01-thermal-setup.sh

Fan Curve

CPU Temperature	Fan Speed
Below 55°C	2700 RPM (near-silent)
55–70°C	Linear ramp to 4500 RPM
70–80°C	Ramp to 6500 RPM
Above 85°C	8000 RPM (maximum)

Monitoring

After running the script, monitor for 2 minutes:

watch -n 2 'sensors | grep -E "Package|fan1"'

Expected: temperatures should drop from 100°C to below 70°C within a few minutes at idle. Fan speed will rise to match load.

Emergency Fan Override

If your CPU is critically hot before running the script:

# Find your fan sysfs path
find /sys/devices/LNXSYSTM:00 -name "fan1_output" 2>/dev/null

# Force fan to maximum (replace path with yours)
echo 1 | sudo tee /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:1c/APP0001:00/fan1_manual
echo 8000 | sudo tee /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:1c/APP0001:00/fan1_output

# Return to automatic control
echo 0 | sudo tee /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:1c/APP0001:00/fan1_manual

Verifying mbpfan is Running

systemctl status mbpfan
sudo journalctl -u mbpfan -n 30 --no-pager