What it usually means, the likely causes in order, what to safely try first, what a pro charges in Canada, and when to stop and call one.
This guide covers the common cases. Describe your exact problem and get a personalized diagnosis — free to start, with a DIY vs. call-a-pro verdict and a real cost estimate.
A microwave that lights up, hums, turns the turntable, and leaves the food stone cold is doing everything except the one job that defines it. The causes are the high-voltage components (magnetron, diode, capacitor) or a humble door switch that isn't reporting 'closed and safe'. This is the one appliance guide on the site where the DIY section is deliberately short: a microwave's capacitor can hold a lethal charge long after it's unplugged, so the honest first steps are observation and elimination — confirming the door, the settings, and the power — and then a decision about repair versus replacement, made with a phone, not a screwdriver.
Not urgent — no damage progresses while it sits unused, and you can simply stop using it. Unplug it if it makes arcing sounds, sparks, smells electrical, or runs with the door open (that last one should never happen — if it does, unplug it immediately and do not use it again). Otherwise, this is a calm replace-or-repair decision, not a rush.
The magnetron generates the microwaves themselves; it's the heart of the appliance and its most expensive part. When it dies, everything else — light, fan, turntable, timer — can work perfectly while no heating occurs at all.
These support components power the magnetron; when one fails, the magnetron gets nothing to work with even though it may be healthy. The symptoms are indistinguishable from a dead magnetron from the outside — one more reason the diagnosis belongs to a technician with the right discharge tools.
Microwaves have multiple interlock switches that must all agree the door is shut before the magnetron can fire. A worn switch or a door that latches slightly out of alignment can let the controls run while the switches veto the heating — the cheapest fault on the entire list.
A low-power setting left active, a failing control board, or (rarely) a supply issue can produce weak or absent heating. Worth ruling settings out before parts, because 'power level 2' is a free fix.
| Job size | Typical estimate (CAD) |
|---|---|
| Simple fix — the straightforward version of this repair | $110–$250 |
| Major job — complex, hidden, or replacement-level work | $300–$900 |
Estimates only, calibrated to Greater Toronto Area trade rates and adjusted by region on this site — not a quote. Your exact price depends on the cause, parts, and access. A personalized diagnosis narrows this range using your specific symptom.
Your job is elimination: settings, door, outlet. After that, a pro weighs the door switches (cheap) against the high-voltage components (not cheap) — and on many countertop models, the honest professional answer is that replacement beats repair once the magnetron is implicated, while built-in and over-range models, with their installation cost, tip toward repair more often. Ask the technician which component they suspect and what the repair totals versus a comparable new unit.
Because the controls, light, fan, and turntable run on ordinary low-voltage circuits, while heating depends on a separate high-voltage chain (transformer, diode, capacitor, magnetron) plus door interlocks that can veto it. Any break in that chain leaves a microwave that performs a convincing impression of working while producing no heat at all.
If the fault is a door switch: usually yes, it's a modest repair. If it's the magnetron or its power components: on a basic countertop model, repair commonly approaches or exceeds replacement cost, while over-range and built-in models — where installation and fit matter — justify repair more often. A diagnostic visit that names the component gives you the number to decide with.
Yes — magnetrons weaken with age, so food takes noticeably longer before heating fails completely. If your 'one-minute' foods have quietly become two-minute foods over months, that's the pattern of a magnetron on its way out, and it helps the repair-versus-replace decision to know it's progressive wear, not a sudden break.
Possibly — a failing high-voltage component or a shorted door interlock can draw fault current and trip a breaker. Either way it's a stop-using-it signal: repeated breaker trips from an appliance are the protection system reporting a real fault, and the unit should stay unplugged until a technician has looked at it.
Describe what's actually happening and get a personalized diagnosis — DIY vs. call-a-pro verdict, real cost estimate, and top-rated local pros.