Laptop Fan Not Spinning? How to Tell If It's Broken

A silent laptop fan isn’t always a dead one. Plenty of laptops stop the fan on purpose when they’re cool. The time to worry is when the laptop gets hot and the fan still doesn’t come on, or when it throws a fan error at startup. Here’s how I sort out which one I’m dealing with.

Step 1: Is it actually supposed to be off?

Many laptops keep the fan stopped at idle or light use, and only spin it up once the processor reaches a certain temperature. ASUS’s support page says exactly this: depending on the model’s fan design, the fan won’t spin until the system temperature reaches a certain level.

To test it:

• Plug in the charger.
• Run something heavy for a few minutes, like a game, a video export, or a CPU benchmark.
• Listen at the exhaust vent, or put your hand near it.

If the fan comes on as it warms up, it works. If the laptop gets hot, slows down, or shuts off and the fan never starts, keep going. Stop the test if it gets very hot. Running a laptop without a working fan can trigger thermal shutdowns. For heat problems in general, see laptop running hot.

A free monitor like HWiNFO can show fan RPM on many laptops, but not all of them report the fan speed. A reading of 0 alone doesn’t prove the fan is dead.

Step 2: Check fan and power modes

A Silent or Quiet mode in the maker’s app (Lenovo Vantage, MyASUS, Armoury Crate, Dell Optimizer or Power Manager, HP’s apps) can hold the fan off until it’s warmer. Switch to Balanced or Performance and test again. The settings are covered in laptop fan loud or always running.

Step 3: Run the built-in fan test

Most big brands have hardware diagnostics that test the fan directly. This is the most reliable way to know.

• Dell: restart, press F12 at the Dell logo, choose Diagnostics. Dell’s support page says to run the Advanced Test, select the fan entries, and choose Thorough. Write down any error code. SupportAssist in Windows can also scan the hardware.
• HP: restart and press F2 repeatedly to open HP PC Hardware Diagnostics UEFI, then run System Tests > Fan Test. HP laptops that can’t read a valid fan speed at boot show error 90B.
• Lenovo: Lenovo Diagnostics (in Vantage or as a bootable tool) can run hardware tests. ThinkPads can show a “Fan error” message at power-on, and Lenovo has a support article for it.

If the test fails, the fan or its cable is the likely problem. If it passes but you still get errors, try Step 4 before opening anything.

Step 4: Update the BIOS and do a hard reset

Fan control is handled by the laptop’s firmware, so a BIOS bug can cause fan errors or odd fan behavior. HP’s support staff list a BIOS update and a hard reset for error 90B.

• Update the BIOS from your maker’s support site. Keep the charger plugged in and don’t interrupt it.
• Hard reset: shut down, unplug the charger and anything connected, then hold the power button for about 15 seconds. On laptops with a removable battery, take it out first. Then power back on.

Step 5: Open it up and look

Only do this if the laptop is out of warranty, or you’re fine with the warranty risk.

• Shut down, unplug the charger, and remove the bottom cover with the right bit from precision screwdriver set.
• Disconnect the battery if your model allows it, and follow anti-static habits that matter.
• Look for a dust mat on the heatsink fins or something stuck in the blades.
• Give the fan a gentle spin with a plastic tool. It should turn freely and keep coasting for a moment. If it barely moves or grinds, the bearing is likely worn.
• Find the fan’s small cable where it plugs into the motherboard. Unplug it carefully with a plastic tool and plug it back in firmly. A cable that came loose after someone cleaned or upgraded the laptop is a classic cause of a fan error.
• Clean with short bursts of compressed air while holding the blades still.

Reassemble, reconnect the battery, and run the fan test again.

Step 6: Replace the fan

If it still fails the test, or it grinds or won’t spin freely, replace the fan.

• Find the part number. It’s often printed on a sticker on the fan itself, or listed in your maker’s parts lookup or service manual. HP and Dell list them for many models.
• Some laptops have two fans (CPU and GPU), and the test will tell you which one failed.
• On some laptops the fan is a separate part held by a few screws. On others it comes attached to the heatsink. In that case you’ll need new thermal paste when you put it back. See thermal paste and pads.
• Match the connector and the screw layout to your old fan before you buy.

Desktop PC fan not spinning? Check that it’s plugged into the right motherboard header and look at the BIOS fan settings, since many fans stop at low temperatures there too. For dust, see clean a dusty desktop.

When to use a shop

• The laptop is still under warranty. A failed fan is a normal warranty repair.
• It’s a MacBook or a model where the fan sits under the motherboard.
• The fan is new and plugged in, but the test still fails. That can point to a motherboard problem.