BACK STORY: The Case Of The Too-Warm Walk-In

Foodservice equipment repair sometimes requires persistence and a step-by-step process of elimination, especially when older units are involved. No one can attest to this more than Fred Campos, Lead Service Technician for Summit Commercial Facilities, Golden Valley, Minn., who recalls a baffling repair case from about five years ago.

“A service call came in from a large corporate dining facility in Bloomington, Minn., regarding a walk-in cooler health inspectors had marked as being ‘slow to cool,'” Campos says. The walk-in was an older model (mid-’90s), about 112 sq. ft. in size. Its condenser, positioned atop the box, was connected to the evaporator by about 10 ft. of insulated soft copper line-set suspended above the box.

Campos began to eliminate the usual suspects through a series of diagnostic tests. “We inspected and cleaned the evaporator coil, measured refrigerant pressure, nitrogen pressure, and everything checked out just fine,” Campos says. Next, he replaced the original quick-coupled connections where the refrigerant line met the evaporator coil and condensing unit.

“When I went back the next day to follow up, the cooler was still not cooling,” says Campos, who by this point had brought along one of Summit’s senior techs to help out.

“We next looked at the expansion valve (responsible for regulating the flow of refrigerant in the system). When we opened it wider, the compressor suddenly began to frost over, which meant plenty of refrigerant was reaching the compressor—but it was failing to pull heat out of the air,” Campos says. So the service agents replaced the expansion valve.

By the third day, Campos began to fear that the issue might lie in the evaporator itself, which would be a pricey, time-consuming job.

“Before we committed to replacing the evaporator, we wanted to make one more attempt to see if there was a restriction somewhere in the system,” Campos says. They turned their attention to the flexible copper line-set connecting the condenser and evaporator. The line was about 10-ft. long, slightly curved from the length of the run and covered in black insulation that had seen better days. Campos began pulling the old insulation off the line. About halfway through, they discovered the problem.

“Time, gravity and lack of proper support had caused the line-set to bend down just enough to create a kink that blocked the refrigerant flow—kind of like a bent straw,” Campos says.

Once they found the blockage, the fix was straightforward. “We cut out the kink, added an elbow, and added support for the line across its full length—and the cooler began to cool properly again,” Campos says of the unusual repair job. “It was a fluke that the line settled in a way that blocked the flow. But in later repair work on other walk-ins, I’ve always kept the line blockage case in the back of my mind as a possible culprit—and it helped solve at least one other case.”

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