LG Over-the-Range Microwave: Exhaust Fan and Filter Maintenance

How the LG Over-the-Range Exhaust System Works

LG over-the-range microwaves can be configured for external venting (exhausts air through a duct to the outside) or recirculating (filters and returns air to the kitchen). The configuration determines which filters need maintenance and how often.

Grease Filter Cleaning

The metal mesh grease filter(s) below the microwave catch grease particles from cooktop cooking. They should be cleaned monthly for normal cooking or more often for frequent frying.

1. Slide or snap the filter(s) out from the bottom of the microwave.
2. Soak in hot water with dish soap or run through the top rack of the dishwasher.
3. Rinse thoroughly and allow to dry before reinstalling.
4. A heavily grease-soaked filter that is difficult to clean should be replaced — they are inexpensive and sold at appliance parts retailers.

Charcoal Filter Replacement (Recirculating Models Only)

Recirculating microwaves use a charcoal (carbon) filter to absorb cooking odors. Unlike grease filters, charcoal filters cannot be washed — they must be replaced every 6 months or when odors become noticeable.

1. Locate the charcoal filter behind the top vent grille (remove 1–2 screws to open the grille).
2. Remove the old filter and note the part number.
3. Install the new filter in the same orientation.
4. Reinstall the vent grille.

External Vent Duct Cleaning

Externally vented microwaves require annual inspection and cleaning of the duct. Grease accumulates in the duct over years and can become a fire hazard. The exterior vent cap should be checked for proper operation — the damper flap should open when the fan runs and close when off.

Filter Reset Light

LG microwaves display a “Filter” reminder light at set intervals. Pressing and holding the filter reset button for 3 seconds clears this reminder after you have cleaned or replaced the filters.

Fan Speed and Noise

If the exhaust fan seems weaker than usual or is making a grinding noise, the fan motor bearings may be wearing out. This is common on units over 5 years old. A technician can replace the fan motor without removing the entire microwave from the wall in most cases.

Why Professional Service May Be the Right Choice

While many Microwave issues can be addressed with the steps in this guide, there are situations where attempting a DIY repair can make the problem worse or void your warranty. If you've followed the steps above and the issue persists, or if you're not comfortable working with electrical components or water connections, calling a factory-certified technician is the safest and most cost-effective path forward.

LG Appliance Experts technicians are trained directly to LG's service specifications. They arrive with the most common OEM replacement parts already on the vehicle, which means most repairs are completed in a single visit — no waiting for parts to be ordered.

Preventing the Problem from Recurring

Most Microwave issues that require repair are preventable with regular maintenance. Key habits that extend appliance life and reduce fault frequency:

• Clean filters regularly. Lint filters, drain pump filters, and water inlet screens accumulate debris over time. A clogged filter is one of the most common causes of performance issues and error codes.
• Don't overload. Consistently running your Microwave beyond its rated capacity puts extra stress on the motor, drum bearings, and suspension components.
• Use the correct detergent and amounts. Excess detergent — especially non-HE detergent in HE appliances — causes buildup, mold, and sensor errors over time.
• Check hoses and connections annually. Inspect inlet and drain hoses for cracks, kinks, or loose connections at least once a year, especially if your appliance is more than five years old.
• Level the appliance. An unlevel Microwave vibrates excessively during operation, accelerating wear on internal components and causing noise and balance errors.

LG Warranty and Service Coverage

LG offers a standard one-year parts and labor warranty on most appliances, with extended coverage on specific components — most notably the 10-year warranty on linear compressors in qualifying refrigerators. If your appliance is still within its manufacturer warranty period, contact LG directly before scheduling an independent repair, as unauthorized service may affect warranty coverage.

For appliances outside the warranty period, LG Appliance Experts provides a 90-day parts and labor warranty on every repair we complete. All replacement parts are genuine LG OEM components sourced directly from LG's authorized parts network.