Richard N San Jose , CA September 27, 2019 Microwave manufacturer recommended replacement of charcoal filters every 6 months the old ones were very greasy and gummed up probably inhibiting air flow and overworking the appliance Easily replaced the 2-4”x6” filters. Read More... Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes Tools: Screwdrivers