Induction cooktop drops out, or will not see the pan

An induction cooktop is a power electronics box with a glass lid. Almost every fault we are called to is either heat, cookware, or a connection — in that order of frequency.

Thermal shutdown is the common one

Under the glass sits an inverter with power transistors that need moving air. The cooktop monitors its own temperature and will reduce power or shut a zone down entirely to protect itself. A zone that drops out after twenty minutes of hard boiling, or a cooktop that goes dark and recovers a minute later, is usually telling you its electronics are too hot.

The reasons are nearly always installation or airflow:

• The intake or exhaust path under the cooktop is blocked. A drawer stuffed full, a shelf added later, or a filler panel fitted at the front closes off the air the unit needs.
• The cooktop was installed above an appliance that pushes heat upward, or in a cabinet run with less clearance than the specification calls for. This is routine in the numbered-street cottages where a modern cooking package was dropped into 1930s cabinet depths.
• The cooling fan itself is dying, or its blades are furred with dust and salt film. Salt aerosol reaches under a cooktop the same way it reaches everything else in a beach house.

A cooktop that has been thermally cycling like this for a long time eventually does damage a power module. Catching it while it is still an airflow problem is much cheaper.

Pan detection

Induction only works with a ferrous base. Before we do anything else we test the pan with a magnet: if a magnet does not stick firmly to the base, the cooktop is behaving correctly by refusing it. Warped or thin bases are the next cause — a pan that rocks or has lifted in the middle loses coupling and the cooktop reads it as absent. Small pans on large zones sometimes fall under the minimum detection diameter for that zone.

Only when the cookware checks out do we look at the coil and its sensor. A single zone that will not detect while its neighbours are fine points at that zone’s coil, its thermistor, or the harness to the power board.

Touch controls

Touch panels fail in two ways here. Moisture and salt film across the glass surface make the controls sluggish or unresponsive — genuinely fixed by drying and cleaning properly. Or the ribbon connection to the control board has corroded, which is not fixed by cleaning the glass. We check both, and we check them before ordering a control assembly.

Power supply

Induction cooktops want a solid 240-volt supply. A loose or oxidised connection at the junction box, or one leg dropping out, produces symptoms that look exactly like a failing cooktop: zones that die under load, erratic behaviour, and intermittent restarts. In houses that have taken repeated storm-season voltage transients, we also check the power board for the tell-tale of a surge event before assuming a component simply wore out. Jacksonville Beach averages around 68 thunderstorm days a year, so this is not a rare cause.

What the visit looks like

We read the fault history if the control keeps one, measure supply voltage under load, test the cooling fan and the clear air path, check coil and sensor resistance zone by zone, and test the customer’s actual cookware rather than ours. Then a written estimate, genuine OEM parts, and a straight answer if the power module is the fault and the sensible economics point the other way.