It's Not the People. It's the Process.
The fact that your team keeps making mistakes and you have to fix them is a symptom that something is missing from your business structure. What's missing are your "Standards." Standards are the processes you define to get something done the way YOU want it to be done. If they are not documented, people will either flounder or do what they think is best. Either way, it's a problem. The Work Breakdown Structure (aka checklist) is critical if you want to avoid mistakes and/or non-standard delivery by your field personnel.
The concept of a "checklist" is not new. Commercial and military pilots go through a pre-flight checklist before every single flight. Not because they don't know what they're doing, but because it removes the possibility that something will be overlooked.
In your HVAC business, you have your own personal delivery standards and processes. In order to ensure that every member of your team performs to the same level as you, it is vitally important to define the processes and provide the checklists.
The brainSHARE Standards Series 3.0 will provide the information you need on processes, checklists, and organization structure that will help you insure your team performs their tasks as you intend.