A warranty document often includes a maintenance condition. It says the covered product must be kept up in a certain way, and the claim may be questioned if it was not. Read that clause before you need the claim, because the time to find a gap is while the unit still works.
Find the clause and its verbs
Search the paper for words such as maintain, service, clean, inspect, follow, use, keep, and record. Each verb marks a duty. Some duties are plain, like keeping the area around the unit clear. Others name a schedule, a part, a fluid, or a person who must do the work. Write each duty on its own line so you can see the whole list at once.
Check the schedule against the owner's manual
Many warranties point back to the manual. Compare the two. If the paper says the manual governs, then the manual's intervals and procedures become part of your duty. If the paper names its own interval, plan around the stricter of the two. Mark any mismatch and ask the seller or manufacturer which one controls.
Ask who may do the work
Some conditions require service by a qualified person. Others allow the owner to perform routine tasks. Ask whether a visit by an unlicensed person, or a task you perform yourself, will be treated as compliant. Get the answer in writing. A verbal answer is hard to use later.
Keep the proof of upkeep
Whatever the condition asks for, keep a dated record of each task, the person who did it, and the receipt or service note. Store it with the install record and the warranty paper. If a condition asks for records and you have none, a claim may stall even when the part failed on its own.
Plan around the life of the unit
A warranty term is not the same as expected service life. A maintenance clause can run past the warranty or end before it. Use the service life guides on this site to set a planning date, then read the warranty for what it asks you to keep up along the way. Check the published tables on this site for the planning figures, and compare them with the ranked service life list for major appliances.