1. Age
A commercial packaged unit that has been maintained commonly lasts fifteen to twenty years. Units near the coast, units that run year-round and units that have been neglected last less. Age alone is not a reason to replace, but it changes how much it is worth spending on a repair.
2. What failed
A capacitor, contactor or fan motor is routine. A compressor or heat exchanger is a major component, and on an older unit the repair can cost a large share of a new one while leaving every other aged part in place.
3. Refrigerant
If the unit uses R-22, any repair that involves the refrigerant circuit becomes expensive, because the refrigerant itself is scarce. That often tips the decision toward replacement.
4. Repair history
Look at the last three years of invoices for that unit. If you are paying for several visits a year, the unit is telling you something.
5. What the unit costs to run
Older units with failed economizers, worn compressors and dirty coils use considerably more energy than current equipment. Over several years the difference can be meaningful, particularly on units that run long hours.
A simple rule of thumb
If the repair costs more than about a third of a replacement and the unit is past the middle of its expected life, get a replacement quote alongside the repair quote and compare them properly.
Questions to ask any contractor
- What exactly failed, and what caused it?
- What else on this unit is near the end of its life?
- What does the repair cost, and what warranty comes with it?
- What would a replacement cost, including crane, curb adapter and permit?
- How long would the space be without air for each option?
A contractor who can only answer the replacement questions is selling. One who can answer all of them is advising.