A comprehensive AMC bundles preventive visits, breakdown labour and replacement parts into one annual fee. It costs more than a labour-only contract because the service provider takes on the risk of expensive parts failing. For the equipment owner, it means predictable costs and no arguments about whether a part is worth replacing.
Comprehensive rarely means everything. Common exclusions include glass, plastic and cosmetic parts, damage from voltage fluctuations or misuse, accidental damage, consumables such as lamps, and sometimes major components like compressors, or refrigerant top-ups beyond a limit. Some contracts also exclude units beyond a certain age. Ask for the exclusion list in writing and compare it across quotes, not just the headline price.
A supermarket in Coimbatore with a long run of display freezers and multidecks might choose a comprehensive AMC because a single compressor or fan motor failure in peak season would be expensive and disruptive. Bundling the risk into a known yearly cost suits its budgeting.