The short answer
A Criterion microwave that runs cold is often set or loaded wrongly rather than broken, and a mug of water at full power separates the two in two minutes. On this class the usual cause is a power level left set low from a previous programme, with a turntable that is no longer turning next to rule out.
What you actually observe
- It heats a cup of water fine but not a plate of food — The oven works and the load is the variable.
- Food is scalding in places and cold in others — That is a distribution problem rather than a power problem.
- NEAR MISS: there is arcing or a burning smell inside the cavity — Stop using the oven now and read the electrical safety page instead.
The causes, most likely first on this brand
- A power level left set low from a previous programme — An oven set to a low power level runs its full time while delivering a fraction of the energy, and nothing about the display makes that obvious. Ranked first on a Criterion unit: the panel on these ovens remembers the last power level used, and a level set once for defrosting explains a great many complaints against the brand.
- A turntable that is no longer turning — A dish that stands still sits in the same pattern of hot and cold spots for the whole cycle, so the food is scalding in places and cold in others and reads as poor heating. Ranked second here: a light plate on a simple coupler is easily refitted off its drive after cleaning.
- More food in the oven than the cycle time allows for — Ranked third here: a compact cavity is asked to heat dishes it was never sized for.
- A magnetron at the end of its life — Ranked fourth here: last, and it is the only one of the four that is not an owner check.
Check in this order, and why this order
- Set a short time at full power deliberately and heat a cup of water — Water that is clearly hot after a couple of minutes at full power tells you the oven works.
- Watch through the door and see whether the plate is turning — A plate that does not move, or one seated off its coupler, is the cause of uneven results.
- Compare the result against a single cup of water heated for the same time — If the cup gets hot and the meal does not, the oven is working and the load is large.
What an owner can safely check
- Clear the panel, select full power explicitly and run a cup of water for a couple of minutes — This is the standard test and it removes the simplest explanation first.
Tools: mugAbout 10 min
- Take the plate and its roller ring out, wash them and refit the plate squarely on its coupler — A plate sitting off its drive is the commonest version of this.
Tools: warm waterAbout 10 min
- STOP HERE if the next step needs a meter on live terminals or a panel off — That is where an owner check ends and a service call begins.
Before you open anything
Safety
Never remove the outer cabinet of a microwave: the capacitor inside holds a dangerous charge long after the power is off, and that remains true of an oven unplugged for days. Never run the oven empty, and never defeat or tape a door interlock. Use a mug of water rather than food for any test, and take it out with care because superheated water can boil over suddenly.
When to call a technician
Call once the power level, the load, the turntable and the supply are all clean and a cup of water still will not heat, because everything past that point is behind a cabinet an owner must not open. Stop using the oven and call at once if there is arcing or a burning smell. Bear in mind when you decide that this is a retailer house brand built by a contract manufacturer, so parts come through the retailer rather than from a brand service network.
Nearest pages of this class
What this page does not cover
This page covers the Criterion microwave as a class, not one family or model line. Component arrangements, power ratings and service procedures all change from build to build and are deliberately not here. Where a family or model page exists for your oven, it is the more specific answer and the one to read first.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
