Diagnosis
The ceramic heating element isn't activating. This could be a failed element, a loose connection, or the thermostat/control board preventing heat mode.
How to Fix It
Make sure it's not just in 'Fan Only' mode. Cycle through the modes using the button or remote. Listen closely when you select a heat setting—you should hear a faint click from the internal relay engaging. If you don't hear that click, the control board might be faulty.
If That Didn't Work
The ceramic plates themselves can crack or the internal wiring can burn out from overheating. There's no safe way to inspect or replace this yourself due to the high-voltage components sealed inside.
Heads Up
Running the fan without heat for extended periods isn't great for the motor. If heat won't engage, stop using it to avoid wasting energy on just the fan.