It still works, so it waits. That's how a gasket turns into a compressor.

1. Torn or flat door gaskets. A gasket that doesn't seal lets warm air into a cooler all day. The compressor runs longer, ice forms on the coil and food warms up. A gasket is a cheap part. A compressor isn't.

2. Doors that don't close on their own. A bent hinge or a broken closer leaves a walk-in or reach-in door hanging open. Same result as a bad gasket, only faster.

3. Slipping or worn fan belts. Rooftop units and exhaust fans often run on belts. A loose or worn belt squeals, moves less air and wears out the motor and bearings. A hood that doesn't draw well pushes smoke and grease into the kitchen.

None of these stop service. The cooler still cools, the hood still pulls and the burner still lights. So they wait for a slow week that never comes.

Meanwhile, each one adds hours of extra work to a bigger part. The bigger part fails sooner, and usually at a bad time.

• Walk the kitchen once a week with this list. Check gaskets, doors, drains, cords and flames.
• Listen for new noises. Squealing at start-up often means a belt.
• Ask the crew. They know which door sticks and which burner is weak.
• Keep a list per store. Write each small problem down with the date. Clear the list on your next service visit.

A planned visit checks the parts behind panels and on the roof: refrigerant pressures, fan motors, contactors and belts. The technician can tell you what's wearing out before it fails. Ask for that list after each visit.