By far the worst-case scenario is that there is an actual fire causing the smell. The good news is that this is usually the least likely cause of the burning smell, but fires can occur within an HVAC system. This is one reason why it’s important to turn your air conditioning system off and inspect your facility right away.
If, when you inspect your system, you suspect there may be a fire, no matter how small, it’s important that your building is quickly evacuated and the fire service contacted. The safety of you, your staff and your customers is always the most important thing to consider in any situation so be sure to conduct a thorough inspection of the system before ruling out a fire.
Locating the source of the problem as quickly as possible is key not only for the system overall but also for reducing any potential safety risks.