Nearly every "my fridge stopped cooling" call is one of two completely different repairs, and you can tell which one you have in about ninety seconds without tools.
One compartment warm, the other still cold is an air-movement or defrost problem. Cold is being made and is not getting where it needs to go.
Both compartments warm together is a compressor, control or sealed-system problem. Cold is not being made at all.
Same complaint from the kitchen. Different parts, different technician, and prices an order of magnitude apart. Anyone who quotes you over the phone without establishing which one you have is guessing.
The ninety-second check
Open the freezer, take out whatever is against the back wall, and look at the rear panel. Then pull the bottom drawer of the fresh-food side out and look behind it.
A solid sheet of frost across the freezer back wall. The defrost cycle has stopped. Ice has grown over the evaporator until air can no longer pass through it, so the fan is pushing against a wall of ice. This is the single most common cause of the warm-fridge-cold-freezer pattern. The part is a defrost heater, a defrost thermostat, or a sensor — all modest.
No frost, freezer cold, and no fan noise from inside the freezer. The evaporator fan has stalled or its motor has died. Cold is being made and is going nowhere. Open the freezer door and press the door switch in with your finger — on most units the fan should run. Silence with the switch pressed is your answer.
Light, even frost on the coil and everything running. Normal. Look elsewhere.
Both sides warm and the compressor running constantly. Go to the back of the appliance.
Both sides warm and total silence. Compressor, start relay or control.
Why "you need a recharge" is usually wrong
Domestic refrigerators are hermetically sealed. There is no service valve and no routine top-up; the refrigerant is not consumed. If a system is genuinely low, it has a leak, and a leak means finding it, repairing it, evacuating and recharging by weight — not "adding a bit of gas."
More to the point, a low sealed system fails both compartments, because there is one refrigerant circuit serving both. So if your freezer is still holding food hard-frozen, the system is not low, whatever anyone tells you. That single fact rules out the most expensive misdiagnosis in the category.
The exception is a dual-refrigeration built-in — Sub-Zero and some high-end integrated units run two independent systems — where one compartment failing alone is exactly what a single system going down looks like.
The condenser, which you can fix yourself
If both compartments are drifting warm and the compressor is running constantly, get to the back or the bottom-front grille and look at the condenser coil.
In a household with a dog or a cat it will be felted over. In a ground-floor flat on a busy street it will be grey with road grit. In an older Boston kitchen with poor ventilation — and there are a lot of those — it will be a mixture of both bound together with cooking grease.
A blocked condenser cannot reject heat, so the compressor runs permanently and the cabinet never gets there. It presents identically to a failing compressor and it is a fifteen-minute job with a vacuum and a coil brush. We check it before anything else, and often enough that is the visit.
While you are back there, check the condenser fan is actually turning. Same symptoms if it is not.
The drain, and the water on the floor
A blocked defrost drain is worth knowing about because it produces three apparently unrelated complaints at once: water pooling under the crisper drawers, ice building in the bottom of the freezer, and — eventually — the frost problem above, because meltwater that cannot leave refreezes onto the coil.
The drain is a small hole at the base of the freezer's rear panel, and it blocks with a plug of ice or debris. Clearing it is a routine part of a defrost-system repair and it is why we clear the drain rather than just replacing the heater.
What is specific to refrigeration in this city
The second fridge. An enormous number of households here keep one in an unheated basement, a back porch or a garage — triple-deckers in Dorchester and Somerville, single-families out through West Roxbury and Milton, barns and outbuildings on the North Shore. Below about 38–40°F ambient a conventional single-compressor unit stops calling for cooling entirely, because the fresh-food side is already cold enough, and the freezer quietly thaws while the machine reports nothing wrong. In January this is one of the most common calls we take and one of the most commonly misdiagnosed. A garage-rated model solves it; a new thermostat does not.
Level floors, or the lack of them. A 36-inch French-door refrigerator in a brownstone or a triple-decker kitchen with half an inch of slope across the opening will not seal at the bottom corners no matter how good the gaskets are. Continuous running, condensation inside, frost in odd places. We shim and level before condemning a seal, and a fair number of these calls end there.
Salt air. East Boston, Southie, Charlestown, Winthrop, Revere, Quincy and the whole North Shore sit close enough to open water that corrosion reaches terminal blocks, relay contacts and board solder joints. It rarely gives a clean failure — you get intermittents. When a cabinet comes off and there is green on the connectors, we clean and re-terminate that section rather than swapping one part.
What to do right now if it is warm
Move what matters to a cooler or a neighbour's freezer. Keep the doors shut otherwise — a closed fridge holds usable temperature for several hours, an opened one for a fraction of that.
Then, if you want the fastest possible repair: find the model number, which is on a sticker inside the fresh-food compartment on the left wall or behind the bottom drawer, and have it ready. With it, and with which of the two patterns above you are seeing, there is a good chance the failed part is on the van at the first visit instead of the second — which on refrigeration is the difference between one day of inconvenience and three.
We treat refrigeration as urgent for exactly that reason: the value of what is inside usually exceeds the cost of the repair.