Many of the repairs we make started as something small: lint packed into a dryer vent, a dishwasher filter that was never cleaned, a front-load washer seal holding water, or refrigerator condenser coils coated in dust. A maintenance visit goes through those points and shows you which ones you can keep up with yourself.
For dryers, vent airflow is a fire-safety issue, not only a drying-time issue. For refrigerators and freezers, clean coils and good door seals help the unit hold temperature. For dishwashers and washers, clean filters and seals help prevent odors, poor cleaning and drain problems.

