If you could only have one maintenance person in your home for a year, the best choice would be an air conditioning and refrigeration technician. That may sound like a narrow expertise, but these mechanics have the widest skill set of any in-home repairmen.
An HVACR (heating, ventilation, air conditioning and refrigeration) technician is an electrician, plumber and chemist all rolled into one.
The refrigeration cycle is the first thing mentioned in any HVACR course. That’s what’s going on in the coil of your fridge or air conditioner. Basically, the refrigerant is changing from liquid to gas, back to liquid again. But in order to get the job done, technicians must be at least part electrician, having some knowledge of volts, watts and amps in the machine. Finally, you won’t get very far as an HVACR tech without plumbing skills. Pressure drops, and pipe repair is common.
Although HVACR licensure might mean the learning curve is a bit higher, refrigeration and air conditioning is usually much easier to break into than most other mechanical trades.