This can be confusing sometimes, so here is an explanation.
A service call entails repairing an immediate problem to get you up and going. While on a service call the expert will diagnose the immediate problem, quote the repair price and complete the repair with your approval. Most all repairs are warrantied for thirty days and are only specific to the repair that was performed. Let’s say you called and had a motor replaced, then a week later your system stopped working again. If for some reason the motor failed again or a wire was not secured tight during the repair, you don’t pay anything. On the other hand, if your drain line had clogged up, you would be responsible for the service call and repair. A clogged drain would be a maintenance issue and not related to the previous emergency repair. Always ask your expert if they can perform a maintenance or get you scheduled soon.
A maintenance call entails keeping an already working system in tip top shape. On a maintenance, the expert will first ensure everything is cycling and working on arrival. They will take temperatures, pressures, visually and physically inspect components, wiring, drain lines, coils and inform you of any issues that you may need to address. Let’s say that you haven’t had a maintenance in years. Once the inspection is complete you may have to pay to get some things up to par. Once that is done, you put a regular routine maintenance in place and just pay the yearly maintenance
It is important to rely on your experts experience. A trained technician can catch failing parts before they cause more extensive and expensive damage. None of us want that.
Preventive maintenance importance
https://www.energy.gov/energysaver/maintaining-your-air-conditioner