A microwave that turns on, the turntable spins, the light works — but food comes out cold — has lost its ability to generate microwave energy. Here's the breakdown.
The Magnetron
The magnetron is the component that generates the microwave radiation that heats food. When it fails, the microwave runs normally but produces no heat. Magnetron failure is the most common cause of a 'cold microwave' and also the most expensive component to replace.
Repair cost: $150–300 parts and labor for countertop models; $200–400 for over-the-range units.
Is It Worth Repairing?
For countertop microwaves under $200, the answer is almost always no — a new unit costs less than the repair. For over-the-range (OTR) or built-in microwaves, the calculation changes significantly. An OTR replacement involves removing the unit, potentially patching the wall, and purchasing a new unit ($300–600), so a $200–250 magnetron repair on a 4-year-old OTR is often the smarter choice.
Other Causes
High-voltage diode: The diode converts AC to DC for the magnetron. When it fails, you often hear a loud humming and get no heat. Repair cost: $80–140 — much more economical than a magnetron.
High-voltage capacitor: The capacitor stores charge for the magnetron. A failed capacitor produces a loud buzz and no heat. Repair cost: $90–150.
Door switches: Microwaves have 2–3 door interlock switches. If one fails, the microwave won't activate the magnetron even though everything else appears to work. This is often cheaper to fix — $80–130.
Safety Note
Never attempt magnetron or capacitor replacement yourself. Microwave capacitors store lethal voltage (2,000+ volts) even when unplugged. Always call a certified technician.
Microwave Not Heating in Houston: Diagnosis and Repair Guide
A microwave that runs, lights up, and turns the turntable but produces no heat is one of the most common appliance complaints in Houston homes. The symptom is unambiguous — food comes out cold after a full cook cycle. The cause is almost always in the high-voltage circuit: the magnetron, diode, or capacitor. Here is what to know before calling for service.
High-Voltage Safety Warning
The microwave's high-voltage capacitor stores up to 2,100 volts DC even when the microwave is unplugged and can hold this charge for days or weeks after the microwave is turned off. This charge is potentially lethal. Do not open the microwave cabinet or attempt to test internal components without proper training and equipment. All microwave internal components must be tested by a technician who knows how to safely discharge the capacitor first.
Houston-Specific Microwave Failure Patterns
Houston's high humidity and year-round heat create specific microwave failure patterns. Over-the-range microwaves in Houston kitchens accumulate grease and moisture from cooking more rapidly than in drier climates. This accelerates magnetron failure because the grease infiltrates the magnetron cooling vents. Houston's frequent power fluctuations during thunderstorm season also cause diode and control board failures in microwaves. We recommend a quality surge protector for all Houston kitchen appliances.
Repair vs. Replace for Houston Microwaves
For countertop microwaves under $200, replacement is almost always more economical than repair — the magnetron replacement plus labor cost can approach the price of a new unit. For over-the-range and built-in microwaves, repair is usually the better choice because installation costs for a new unit can be $150 to $300 in addition to the appliance cost. ProFix Houston offers same-day microwave repair throughout the Greater Houston area. 90-day parts and 30-day labor warranty on all microwave repairs.
Book Microwave Repair in Houston
ProFix Houston services all microwave brands and types throughout the Greater Houston area. For over-the-range and built-in microwaves, we arrive with a second technician when needed for safe removal from wall mounting. Same-day and next-day appointments available. 90-day parts and 30-day labor warranty on all microwave repairs in Houston.