Burnt smell from the chimney: stop, switch off, and read this

This is the one chimney symptom that should end cooking for the evening. Switch the chimney off at the wall, not just the panel, and leave it off.

Why the smell

The motor is running hotter than it should. Either it is fighting a grease-choked fan and cannot shed heat, or its bearings are failing and it is working against friction, or a winding is starting to break down. The smell is insulation or plastic near the motor warming past its limit.

Why not run it again

A motor that has overheated once has already been stressed. Running it again finishes the job, and a motor that fails while running can take the control board with it. There is also grease around it. Heat and grease in a metal box above a gas flame is not a combination to push.

What the repair usually is

• If caught early: a thorough clean of the fan and housing, and a check of the motor's temperature under load
• If the bearings are gone: motor replacement
• If a winding has failed: motor replacement, and a check that the board survived

Do not open the chimney housing yourself to look. The capacitor inside holds a charge even with the power off, and the fan edges are sharp. This is a technician visit.

How to avoid it

Almost every burnt-motor call we take is a chimney that went a year or more without a service. The motor did not fail; it was suffocated. Six-monthly cleaning is the whole prevention.