The answer first
A measured water test turns this from an impression into evidence, and that is the owner job here. Everything past the water test belongs to someone with a discharge tool. On this kind of cabinet a mass-market sub-brand ships a lot of identical cabinets, and identical cabinets fail in identical places.
What you actually observe
- NEAR MISS — sparking inside the cavity — Stop now; that is the electrical page and it is urgent.
- Heating is much weaker than it used to be — A magnetron losing output degrades instead of failing outright, so the decline is gradual.
- It heats sometimes and not others — Intermittent output points to door switches or a thermal cut-out instead of at a dead magnetron.
- The oven cuts out after a few minutes and restarts later — A thermal cut-out responding to blocked ventilation or a failing fan.
The ranking that matters
- Door switch not confirming a closed door — Ranked first: It is the commonest cause of an oven that lights, turns and does not heat, and it is also the cheapest to put right. It sits at the top here because a mass-market sub-brand ships a lot of identical cabinets, and identical cabinets fail in identical places.
- High-voltage components failed — Second: These are precisely the parts that hold a charge, and that is why the cover is a technician boundary and not an owner one.
- Supply not delivering under load — Third: Microwaves draw heavily when cooking, and a marginal socket or a long extension lead sags enough to affect output.
Order of investigation
- Check the vents and the space around the oven — A magnetron is air-cooled, and a cramped shelf creates cut-outs that look like output faults.
- Look into the cavity with a torch — Burnt residue, a damaged coating or a scorched waveguide cover explains sparking and smells at a glance.
- Note whether it heats when cold and stops when warm — That pattern points to a thermal cut-out instead of at a failed magnetron.
What an owner can safely do
- Perform the measured water test — A cup of cold water, full power, a set time, and record how warm it gets. Repeat it the same way each time.
Tools: measuring cupAbout 10 min
- STOP HERE — the cover does not come off — A microwave capacitor holds a charge after the oven is unplugged, and it is discharged with a tool by a technician.
- Clean the cavity and the waveguide cover — Wipe out burnt residue with a damp cloth; a scorched cover is a finding instead of a cleaning problem.
Tools: clothAbout 15 min
Power, water and hands
Safety
Unplug it, and leave the unit closed. The stored charge in a microwave capacitor is the hazard that makes this class different from every other appliance in the kitchen, and no owner-side check requires that cover to come off. The door latch assembly and its switches are what keep the magnetron from running with the door open — leave that hardware exactly as the factory set it, and stop using an oven whose door does not close cleanly.
When to book a visit
The line here is the case itself. The water test, the vents and the cavity are owner work; everything inside is not. Bring the technician your notes instead of your theory; what you observed is worth more than what you concluded.
Nearest pages of this class
Scope of this page
This is generalized information for the Comfee microwave class. This one names the signature across Comfee microwaves and stops there — it does not identify your control board, your gasket profile or your service part, and it does not reproduce a factory procedure. Part numbers, harness colours and service-mode entry codes are not published here for exactly that reason. It also leaves out anything specific to a rebuilt or previously repaired unit, where the last repair is part of the picture.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
