Can Lightning Damage My AC Unit?

Lightning is a common foe to many Floridians. Often accompanying major storms such as hurricanes lightning is particularly heavy in the Sunshine state. One of the major issues we see as professional ac technicians in Orlando, FL is lightning related damage. It’s almost like Florida is the lightning capital of the US.

Lightning can strike anywhere, but Florida — the “lightning capital” — is particularly prone, says Amitabh Nag, a scientist at the Florida Institute of Technology.

“So one thing we know about Florida it is hot and humid — and it is precisely this reason why we have a lot of lightning,” Nag said.

Florida’s geography also puts it in the bullseye. Two warm bodies of water surround it, and that sea breeze brings hot air inland, where it rises to form towering thunderclouds.

The Sunshine State overwhelmingly leads the nation in the number of lightning strikes, and also deaths: 52 since 2007, and five this year already.

Source: CBSNews

Lightning is also particularly dangerous to home appliances as well as your air conditioning system. Many safeguards are built into the installation and function of HVAC units. However, severe thunderstorms can create heavy enough surges to completely bypass safeguards and/or destroy those safeguards. Yet for every burnt out total home surge protector you usually have a safe operating air conditioner. Below are some common failures points associated with lightning damage in the Orlando, FL area.


Your contactor acts the primarily power switch for your compressor located outside the home. Compressors require large current loads. A contactor uses a small electrical motor on lower current provided from your interior thermostat to switch and/or bridge the gap between the high voltage posts within the contactor. Current from the home passes between the now connected posts and reaches the compressor creating a pathway between the two. Once this pathway is created the compressor will kick on and begin normal operation. Being a mechanically driven switch there are several areas ripe for failure with lightning related conditions.

The common issue is called pitting and can actually also occur over time during normal usage. When a contactor is pitted it will sustain slight heat related pock marks and indentations throughout the posts and the connecting bridge. These can cause sparks, shorts and ultimately heat the contactor to the point where it fuses or snaps under the heat. If it snaps you replace the contactor. If it fuses you will most likely find out when the compressor runs itself into the ground from constant power.

Lightning can exacerbate this issue or all the small steps in between all at once in a single strike. Lightning strikes can also melt or fuse the entire contactor box causing massive damage to your air conditioning system. In the event your home or neighborhood is struck by lightning you should always have a professional spot check your HVAC unit. They can identify possible breakpoints in your system design and check for damage. A preventative maintenance check is always cheaper then replacing a component in your ac system.


Your air conditioning system’s compressor is the heart of your HVAC system. In a striking similarity with human hearts if it receives a strong electrical shock it can cause massive malfunctions. Strong electrical shocks are also used as a means of starting “stuck” compressors. Compressors as their name states compress and push freon through your system in a continuous loop of cooling and heating gas. They use a large electrical motor to power a compression cycle within the sealed unit. 

The primarily result of a lightning strike on a compressor is a blown motor. Considering that the motor is sealed within the unit it is not a simple repair job. Compressors are singular replacement pieces that cannot be repaired within a shop and must be sent to a manufacturer to be repaired and resealed. Air conditioning compressors represent almost half of the cost of the HVAC system in your home. It is almost always prudent and cost productive to put safeguards into place to prevent any accidental damage to your ac compressor. These safeguards usually appear as home surge protectors or smart disconnects. When the current peaks it can trigger a switch or burn through the conductor to dissolve the connection preventing damage to sensitive equipment behind the protective element. A qualified professional ac technician can install and test these features to give you piece of mind.