This isn’t an electrical story. I’m allowed to tell HVAC stories because in 22 years in the trade I’ve worked with enough good HVAC techs to absorb their stories, and because there’s an electrical angle at the end that’s part of why I’m writing this.

A buddy of mine — call him Ray — runs a small refrigeration service shop in East Texas. Commercial only. Restaurants, grocery stores, the occasional medical facility. Ray called me a few months back to ask if I’d ever had to do a service-equipment inspection on a building where the customer had been talking about “weird smells” and “headaches” for a few weeks before the call came in. I had not. He had. This is his story, as he told it to me.

The call

Restaurant on the south side of Tyler. Mid-July. Walk-in cooler in the back of the kitchen — about 8x10, your standard restaurant walk-in for produce and beer. Owner reported the box was “not as cold as it used to be.” Thermostat set to 38, holding at 44. Not failing outright, just sliding.

Ray gets there in the morning. Kitchen staff are prepping for lunch service. Ray says one of the prep cooks mentions, casually, that she’s had a headache “for like two weeks every time I’m in this section of the kitchen.” Ray nods, doesn’t think much of it. The kitchen is hot, sticky, busy. Lots of reasons to have a headache.

Ray gets his gauges, opens the walk-in, steps in to start his diagnostic. The light is on. The fan is running. The box smells like cardboard and produce.

He starts working at the evaporator. Pulls the cover off. Checks the coil. Visual inspection first, then he’s going to pull pressures. He’s been in the box maybe ten minutes when he notices he feels off. Lightheaded. He chalks it up to bending over with his head near a cold coil, gets up to stretch, and realizes the lightheaded feeling stays. Stronger than it should be.

He gets out of the box and stands in the kitchen. Two or three minutes later, he feels fine.

The diagnostic

Ray’s a good tech. The lightheaded thing flagged something in his head. He went out to his truck and got a refrigerant detector. The cheap consumer-grade kind, but it does the job. He stood in the open doorway of the walk-in and held the detector low — knee height, ankle height. The detector started clicking before he got it through the door.

The leak was in the evaporator coil. R-404A. He’d been working in a small enclosed space with a slow refrigerant leak that had probably been ongoing for several weeks. R-404A is heavier than air. It pools at the floor of the walk-in. The fan was running, which was actually keeping the situation less bad — it was circulating the air, displacing some of the buildup. With the fan off, the box would have been worse.

Ray called the owner, shut the system down, ventilated the box for an hour with the door open and a portable fan, then went back in with proper monitoring and finished the diagnostic. Coil leak, full evac and recharge, new coil ordered.

The prep cook with the headache for two weeks? That was the leak. She’d been pulling product out of that walk-in twenty times a shift, breathing low air in a partially refrigerant-saturated box. Not enough to kill her. Enough to give her low-grade hypoxia headaches for two weeks. The owner had been brushing it off as the cook needing more sleep.

What Ray does differently now

A few things.

He keeps a refrigerant detector in his truck and uses it before stepping into any commercial walk-in or reach-in with a reported cooling issue. Twenty seconds of waving the detector around the doorway tells him whether he’s about to walk into displaced air. He says it’s now the second thing he does on a call, right after checking the disconnect.

He carries a personal multi-gas monitor for jobs in confined refrigeration spaces. The detector he uses for the doorway check is a refrigerant-specific one. The multi-gas monitor stays clipped to his belt while he works inside the box. It alarms on O2 displacement, CO, and refrigerant. He bought the monitor used off a friend who’d retired from oil-field work. He says it was the best $400 he’s ever spent on tools.

He pays attention when kitchen staff casually mention symptoms. The prep cook’s two-week headache wasn’t a coincidence. The owner’s “the box isn’t as cold” wasn’t separate from the cook’s headache. They were the same problem reported by two different people who didn’t realize they were describing the same thing.

The electrical angle

Here’s why I’m telling this story on an electrical column.

I get called to commercial buildings to inspect service equipment more often than you’d think. Often after a flag from a fire inspector or an insurance carrier. I’m there for the electrical service, not the HVAC. But I’m walking through the building.

What Ray taught me is that walking through a commercial kitchen, restaurant, or grocery operation isn’t a neutral act. If there’s an HVAC problem, an electrical problem, or a combination, the symptoms can show up in the people working there before they show up in the equipment. A kitchen staff member with persistent headaches, a stockroom worker who keeps feeling lightheaded, an office worker complaining about a smell nobody else notices — these can be real.

When you do walk-throughs in commercial spaces, ask. Not in a way that alarms people. Just casually. “Anything weird about this space?” “Anyone been getting headaches?” If somebody says yes, take it seriously. The cost of being wrong is zero. The cost of missing it is what Ray almost found out the hard way.

Stay safe.

— Mike