After a hurricane power outage: restarting your AC and walk-in safely

When a storm takes the power out, the AC and the walk-in need some care before you open again. This checklist covers what to do before the storm, during the outage and when the power comes back. It's based on guidance from the FDA, Florida's Division of Hotels and Restaurants, FPL and the Electrical Safety Foundation. Where we quote a rule, we link the source.

Before the storm

• Put a thermometer in the walk-in and write down its normal reading. The FDA recommends keeping appliance thermometers in refrigerators and freezers so you can check them after an outage (FDA). If you keep a daily log, you already have the normal number. Our printable walk-in temperature log works for this.
• Add ice early. Florida's Division of Hotels and Restaurants tells food service operators to add bags of ice or dry ice to refrigerators and freezers before the emergency, if there is warning and a long outage is expected (DBPR bulletin 2022-02). The FDA also suggests freezing containers of water and finding out where to buy dry ice and block ice.
• Get food off the floor. The FDA advises storing food on shelves out of the way of contaminated water.
• Write down your outage plan. Who checks temperatures, how often, and where they write them down. The Conference for Food Protection's emergency plan for food businesses recommends this, and says that if food temperatures weren't monitored during an outage and may have gone above 41°F, the food should be discarded (CFP Emergency Action Plan).
• Ask about surge protection. FPL recommends whole-building surge protection that combines inside and outside devices. It also recommends a time-delay relay on the AC if it doesn't already have one. The relay stops the unit restarting for about three to five minutes, which FPL says reduces the chance of damage to the compressor (FPL outage guide). Your electrician or AC company can tell you what your units have.
• Follow any order to shut off utilities. If you're told to switch off the main power, the Electrical Safety Foundation says to turn off each breaker first, then the main breaker (ESFI).

During the outage

• Keep the walk-in door shut. Florida's guidance is to keep cooler and freezer doors closed while the power is off. The CFP plan suggests tape and signs so staff don't open the walk-in out of habit.
• Write down the time the power went out. Then check and record food temperatures with a probe thermometer. Reach-ins and open cases lose cold faster than a walk-in, so check them more often (CFP).
• Don't put hot food into the walk-in. It warms everything else (CFP).
• Turn the AC off at the thermostat and switch off other equipment. Ready.gov says power can come back with brief surges or spikes that cause damage, and recommends turning off or disconnecting appliances and equipment (Ready.gov).
• Don't open without power. Florida's bulletin says not to operate if you have no electrical power (or generator) to run essential equipment, or no safe water supply. If you use a generator, keep it outdoors and at least 20 feet from windows and doors (Ready.gov).

How long is the food safe? Federal guidance for household refrigerators says a closed fridge keeps food safe for up to 4 hours, a full freezer for about 48 hours and a half-full one for about 24 hours (FoodSafety.gov). A walk-in isn't a household fridge, so don't count on those numbers. For a Florida food business, the number that counts is how long the food itself has been above 41°F. That's why the probe readings matter.

When the power comes back

1. Look before you switch anything on. If water reached the AC's outdoor unit, the electrical panel or the walk-in's condensing unit, leave the power off. ESFI says to keep the power off until an electrician has inspected the system, and not to turn on or plug in anything that got wet until the electrician says it's safe. Goodman, the AC manufacturer, advises not starting an HVAC system after a flood until a qualified technician has inspected it (Goodman). Never touch a breaker with wet hands or while standing on a wet floor (ESFI).
2. Check the breakers. The CFP plan lists checking that breakers have been reset as part of reopening. FPL says that if the AC breaker has tripped, wait five minutes before resetting it. If it trips again, don't reset it, and call an electrician. More on that in our post on an AC that keeps tripping the breaker.
3. Watch the lights. If lights go dim or bright and stay that way, FPL says to turn off major appliances and equipment and call FPL right away.
4. Write down the time the power came back, then turn the AC back on and check that the walk-in is pulling back down. The CFP plan says refrigeration should be back to 41°F or below before normal operation.
5. Go through the food. Florida's rule, in the Division of Hotels and Restaurants' own words: "When power is restored, identify all time/temperature control for safety foods (TCS) that may have been above 41°F or below 135°F for more than four hours. TCS foods that have been out of temperature for more than 4 hours must be properly discarded." Thawed frozen food can be refrozen if it still has ice crystals and is at 41°F or less. Throw out any food that touched floodwater. The bulletin ends with: when in doubt, throw it out.
6. Check the ice machine. The CFP plan says to check ice machines for water from melted ice and clean and sanitize food-contact surfaces as needed. If a boil water notice is in effect, Florida's bulletin says to turn off ice machines and beverage machines until it's lifted.
7. Check whether you need permission to reopen. If you were ordered to close, you can't reopen until the regulator authorizes it (CFP).

When to call a technician

• Any AC unit, walk-in condensing unit or panel that sat in water. Don't run it first to see if it works.
• The AC breaker trips again after one reset.
• The walk-in can't get back to 41°F or below. Our guide to a walk-in that won't hold temperature covers the usual causes.
• The AC runs but the air isn't cold, or it sounds different from before the storm.

When you call, say what happened: how long the power was out, whether there was water near the unit, and what the breaker did. Our post on what to tell your HVAC company when you call has more on this.

Where monitoring fits

After a storm there is a lot to check, and the AC on the roof is easy to forget until the room warms up. A SmartHVAC sensor on the unit watches it around the clock. If the unit starts working harder than it should, or the air isn't as cold as it was, you get an alert by email and on your phone, in plain language. It doesn't fix anything, and it doesn't replace probing the food in your walk-in. It tells you which unit needs a call.

Common questions

How long can a walk-in cooler go without power?

There's no fixed number. It depends on how full it is, how often the door is opened and how hot it is outside. In Florida, the rule is that time/temperature control for safety (TCS) food that has been above 41°F for more than four hours must be discarded. Keep the door shut and check the food with a probe thermometer.

Should I turn off my AC during a power outage?

Yes. Ready.gov recommends turning off or disconnecting appliances and equipment, because power can come back with surges that cause damage. Turn the AC back on once the power is steady.

Can I run my AC if the outdoor unit was flooded?

No. Have it inspected first. ESFI says not to turn on anything that got wet until an electrician says it's safe, and Goodman advises a full inspection by a qualified HVAC technician before starting a flooded system.