The usual rule of thumb is that if a repair costs more than about half the price of replacing the unit, you replace it. That is a reasonable starting point but it misses most of what actually matters: repair history, parts availability, what refrigerant the system uses, the condition of the room itself, and what downtime costs your venue.
1. How often has it already failed?
One fault on an otherwise sound system is just a fault. Three faults in a year is a pattern, and the pattern usually means the system is past the point where individual component repairs represent good value. Keep a rough record of what has been done and when, because it is the single most useful piece of information in this decision and almost nobody has it to hand.
2. Can you still get parts?
Parts availability sets a hard ceiling on how long a system can sensibly be kept running. Once controllers, fan motors or valves for a particular unit become difficult to source, every future fault carries an unknown delay attached to it. A repair that takes three days to get a part is a very different proposition to one done the same week.
3. What refrigerant does it use?
Older systems running phased-down refrigerants face rising costs and shrinking supply. If a system has a leak and uses a refrigerant that is getting harder and more expensive to obtain, the economics shift toward replacement faster than the repair quote alone suggests. This is worth asking about specifically, because it changes the picture and it is not obvious from looking at the unit.
4. Is the fault in the plant or the room?
This is the distinction people most often miss. A cool room is a refrigeration system and an insulated box, and they age separately. Failed panel insulation, water damage in the floor, a door that no longer seals or frame that has dropped will defeat perfectly good refrigeration. Replacing the plant on a tired room means paying for equipment that then has to work just as hard as the old one did.
5. Does it still suit what you use it for?
Venues change. A room specified for one menu, one volume and one delivery pattern may be carrying a very different load now. If you regularly run out of space, prop the door while loading, or find the room struggling to recover after a delivery, the real problem might be that the system is correctly sized for a business you no longer run.
6. What does a day of downtime actually cost?
Work this out honestly, because it is usually the number that decides it. Add the stock at risk, the trade lost or disrupted, the staff time spent managing around it, and the emergency callout. Then consider how many of those days you are likely to have over the next two years if you keep repairing. Against that figure, planned replacement in a quiet week often looks very different to how it looks on the quote alone.
When replacement is the only answer
If a system has a significant leak in the sealed system on an older unit using an increasingly scarce refrigerant, and the room itself has deteriorated, repair is generally throwing money at something that will not last. That combination is the clearest case there is.
Everything short of that deserves an actual assessment rather than a rule of thumb. The useful conversation covers the fault, the history, the room, the load and the downtime cost together, and ends with a straight answer about which way it points.