Extra cash installing A/C units for another company

I own a busy A/C installation business. The only thing we do is install new A/C systems in homes. We don’t have repair services, and we don’t install any type of heating devices. We are a subcontractor service, hired by other busy A/C installation businesses. When other companies have too many installations scheduled, they call a subcontractor to help. I worked for 15 years in a busy HVAC repair center. After that, I decided to open my own A/C installation business. I work with a few different contractors in the city. We usually have A/C installation jobs scheduled every day, especially during the summer. The summer is the busiest time of the year for our business. I had to hire two additional employees this year, because we were installing three or four A/C units every single day. A typical A/C installation job often lasts for 4-6 hours. We have two or three teams working on A/C installations at the same time. I had to roll up my sleeves and join the crew last week. We had 11 jobs scheduled over a three days period. I jumped in one of the work vans, and performed an installation. I took one of our new A/C installation technicians to help. He is still working on his certification hours, so he can’t actually install any of the pieces or parts. He is simply there to fetch items from the truck or hand me tools. It gave me a chance to work with the new guy and see what skills he can bring to the table.