Complete System Breakdown: If your furnace or air conditioner completely stops working during severe temperatures, it's an emergency. In extreme heat or cold, a non-functional HVAC system can pose risks, particularly for infants, the elderly, or those with health conditions.

Gas or Carbon Monoxide Leaks: This is a critical safety issue. If you smell a "rotten egg" odor near your gas furnace, you may have a gas leak. Carbon monoxide is a colorless, odorless gas that can be deadly. If your carbon monoxide detector goes off or you notice signs like a yellow or flickering furnace flame, evacuate your home immediately and call the gas company and emergency services from a safe location.

Burning Smells or Smoke: A burning smell or visible smoke from your HVAC unit can signal an electrical issue or an overheating component. Shut off the system immediately at the thermostat and the circuit breaker to prevent a potential fire.

Refrigerant Leaks: If you notice a hissing sound, a frozen evaporator coil, or a sudden loss of cooling, it could be a refrigerant leak. This not only harms the environment but can also be a health hazard and lead to catastrophic system failure.

Loud, Unusual Noises: Banging, screeching, or grinding sounds are not normal and should be addressed immediately. These noises often indicate a failing motor, a broken fan blade, or other serious mechanical issues that can cause irreparable damage if left unchecked.

Repeatedly Tripping Circuit Breakers: An HVAC system that keeps tripping your circuit breaker is a strong indicator of a serious electrical problem. This requires a professional diagnosis to prevent damage to your electrical system or a fire.