Nobody works for free. It doesn’t matter if it’s a plumber, electrician, or an HVAC tech. someone somewhere has to pay their hourly rate, workers comp, insurance, and put the gas in the service truck.
So when an air conditioning company advertises cheap service calls you can expect to be the victim of a bait and switch. All they want is to get their foot in the door. You can bet they will find some major problem with your A/C system, and you may even be told you have to replace it.
Calling the company with the lowest service call fee could result in you being ripped off.