The labor issue might be due to the seasonality of the business. (The labor issue: 300,000 HVAC professionals in the USA but just 145,000 companies). In fact,

The labor issue might be due to the seasonality of the business. (The labor issue: 300,000 HVAC professionals in the USA but just 145,000 companies). In fact, the business is initiated just two days of the year! The first hot day of summer and the first cold day of winter. When somebody's old system breaks and they find out exactly when they need it most! So it's always an emergency, and always when it's very unpleasant to work outdoor. Seems clear why nobody is going into the business. One of those 'dirty jobs'. Maybe a business model that spread things out? Like, a contract to support heating and cooling year-round, schedules upgrades, does periodic testing to anticipate breakdown. I imagine now it's more like folks that have snow-plow trucks, promise to plow out your parking lot after each big snow. They work just a couple days a year in Iowa, and have regular jobs the rest of the year. The companies are less than half a dozen trucks typically, with a huge demographic spike at 'one guy, one truck'