Display case and merchandiser repair

How display cases actually fail

Ranked by what we actually find: defrost system faults first, where progressive ice blocks airflow until the case cannot hold temperature. Evaporator fan motor failure second, uneven cooling, fast frost build-up and hot spots along the case. Compressor problems account for roughly a quarter of cooling-system issues and are by far the most expensive.

What makes cases different from a closed box is the two systems that do not exist on a walk-in: the air curtain and the anti-sweat heaters.

The air curtain

An open multideck holds temperature by projecting a curtain of chilled air across the front. It is a fragile thing. Product stacked above the load line disrupts it. A failed or slowing evaporator fan disrupts it. A store door opening onto the case, or a fan blowing across the aisle, disrupts it. In every one of those cases the refrigeration circuit reads normal and the product is warm, which is why cases get misdiagnosed more than any other equipment we work on.

Anti-sweat and mullion heaters

Glass doors and case frames carry small heaters to stop condensation forming. In a New England summer, with dew points running high for weeks, these work hard. When one fails you get fogged glass and water tracking down the frame, a presentation problem that customers notice immediately, and a slip hazard on the floor in front of the case.

Markets, delis and rack systems

A long run of open case work on a shared rack fails differently from a self-contained merchandiser. One condensing unit problem empties a whole department at once, and the diagnosis has to separate a rack-level fault from a case-level one before anyone starts pulling panels. Greater Boston has a lot of this, the ethnic markets along Quincy’s Hancock Street corridor, Malden Center, Chelsea, and the supermarkets fed from the produce district.

Common questions

Related