Safety first: Unplug the unit and allow it to cool. Heating components can retain heat for some time.

Steps to troubleshoot:

Confirm no heat: Run a timed dry cycle for 5–10 minutes. Open the door and feel for warmth inside the drum. If completely cold, proceed.
Access heater assembly: Remove the rear panel to access the dryer heater assembly mounted in a metal housing.
Inspect wiring: Look for burnt connectors or discolored wires at the heater terminals. Repair or replace damaged wiring.
Test heating element: With power disconnected, remove at least one wire from the element and measure resistance across the terminals. An open circuit indicates a failed element.
Replace heater if open: Remove mounting screws and install a new dryer heating element assembly. Reconnect wires firmly.
Control board check: If the element tests good, the heater relay on the main control board may not be energizing. This typically requires board replacement by a technician.

After repair, run a short dry cycle and verify that the drum heats properly and 3H does not reappear.

Dryer does not heat; 3H appears during dry cycles.

Possible Causes