The call was the usual one: walk-in warm, compressor running non-stop.

Inside, the unit cooler was a block. Not frost. Solid ice, hanging off the coil and the fan shrouds. A Russell UEL2-304, medium temp, R-404A, two 3/4 HP fan motors, and by the serial number, built in 1998.

A medium-temp box shouldn’t do this on its own. It runs above freezing, and the coil sheds most of its frost between cycles. What finishes the job is the defrost circuit. This coil has electric heaters (the plate rates them at 23.5 amps on 208 volts). If they don’t get called, or one leg is open, frost stays. Frost becomes ice. Ice insulates the coil so well the fans are just moving cold air past a block.

Once it looks like this, the compressor is running against nothing. Suction drops, the box warms, the meter spins. Nobody can diagnose much until it’s thawed, so step one is always the same: shut it down, thaw it properly, then find out why the defrost stopped.

We tested the heater circuit and the defrost control, got it back to a working coil, and measured the housing. That’s the blue 76 in written on the side. A coil built in 1998 has done 27 years in a kitchen. When the next thing goes on it, the answer is a new unit cooler, not another part, and now we have the number ready.

For operators: if you see ice, not frost, on a medium-temp coil, the defrost has already failed. Don’t chip at it with a knife. Call before the product warms.

If it heats or cools, we handle it. 📞 718-802-1700