A Utah heat wave is the wrong time to discover that your air conditioner has a clogged filter, a blocked outdoor coil, or a thermostat schedule that is not doing what you expected. The best preparation happens before the hottest afternoon: give the system a normal test run, remove avoidable airflow restrictions, lower the home’s heat load, and decide what your household will do if cooling is interrupted. If the system is already struggling, Larsen Heating & Air’s AC repair service is the right place to start.

This guide is deliberately about prevention, not emergency troubleshooting. It shows what a homeowner can safely check in advance, what warning signs deserve a service call before the heat arrives, and how to build a simple heat-safety backup plan.

A practical AC checklist before the heat arrives

Use this short list when a stretch of extreme heat appears in the forecast. Start as early as you reasonably can; a National Weather Service Extreme Heat Watch specifically means conditions are favorable and it is time to prepare.

  • Run one complete cooling cycle during the cooler part of the day and note whether the system starts, cools, and shuts off normally.
  • Check the air filter and replace or clean it if it is visibly dirty, following the equipment and filter instructions.
  • Make sure supply registers and return grilles are open and unobstructed.
  • Clear loose leaves, grass clippings, weeds, and stored items away from the outdoor unit without opening its cabinet.
  • Review thermostat mode, fan setting, schedule, batteries, and any smart-home or utility overrides.
  • Close obvious air leaks and plan how you will limit direct sun and indoor heat during peak afternoon hours.
  • Schedule service before the heat wave if you notice weak airflow, short cycling, unusual noise, water, ice, or repeated breaker trips.
  • Choose a backup air-conditioned location and identify anyone in the household who may need extra help if cooling is lost.

1. Test the system while there is still time to respond

Set the thermostat to Cool, choose a normal comfortable set point below the indoor temperature, and leave the fan on Auto unless your equipment instructions call for something different. Let the system complete a full cycle. Walk through the house and pay attention to whether air reaches every main living area, whether the thermostat temperature moves in the expected direction, and whether the outdoor unit starts and stops with the indoor equipment.

This is not a precision performance test. Outdoor temperature, indoor humidity, equipment design, insulation, ductwork, and the home’s heat gain all affect how quickly a house cools. The goal is simply to catch a clear change from normal before demand peaks. A room that has always been a little warmer is different from suddenly weak airflow everywhere, a system that will not shut off, or a thermostat that climbs while the equipment runs.

Write down what you observe: thermostat temperature, time of day, which rooms feel different, whether the outdoor fan is operating, and any sound or odor. Those details make a later diagnosis more efficient and are more useful than repeatedly changing the thermostat.

2. Give the system an easy airflow win

A clean, correctly fitted filter is one of the highest-value homeowner checks. ENERGY STAR advises checking central air-conditioner, furnace, and heat-pump filters monthly and cleaning or changing them when dirty because a loaded filter slows airflow and makes the system work harder. Its HVAC maintenance checklist also separates safe homeowner tasks from coil, refrigerant, drain, and electrical checks that belong in professional service.

Turn the system off before opening the filter access. Confirm the filter size, note the airflow arrow, and make sure the replacement sits flat without gaps around the frame. Do not assume that the densest filter is automatically best. Higher-efficiency filters can be valuable, especially when smoke is present, but the filter must be compatible with the blower and filter slot. If you are unsure, use the equipment manufacturer’s guidance or ask a technician.

Then check the rest of the air path. Move furniture, rugs, curtains, toys, and boxes away from supply registers and return grilles. Avoid closing a group of vents to force more air elsewhere; that can change system pressure and may reduce overall airflow. If one room still lags after obstructions are removed, note it for a duct, balancing, insulation, or heat-gain evaluation.

3. Clear the outdoor unit without turning it into a DIY repair

The outdoor condenser has to release the heat collected inside the house. Loose debris, overgrown plants, grass clippings, and stored objects around the cabinet can interfere with that job. With the equipment off, remove loose material from the surrounding ground and trim vegetation so the unit has open space around it. Keep irrigation spray, dryer exhaust, and new landscaping from blowing debris toward the coil.

Stop at visual housekeeping. Do not remove panels, reach through the grille, handle electrical components, bend fins, or pressure-wash the coil. An intact cabinet can still contain high voltage, and aggressive washing can damage delicate fins or push debris deeper. If the coil is matted, oily, damaged, or difficult to reach, include professional cleaning in a pre-wave service visit.

4. Review the thermostat before the forecast becomes a crisis

Confirm that the thermostat is actually controlling the cooling equipment: Cool mode is selected, the fan is on Auto for normal cooling, the clock and schedule are correct, and batteries are fresh if the thermostat uses them. Look for vacation holds, eco modes, geofencing, demand-response events, or app permissions that may change the set point without being obvious at the wall.

Choose a schedule your household can live with through the hot stretch rather than making constant large adjustments. If the thermostat is in direct sun, near a lamp, above electronics, or in the path of a supply register, mention that when you schedule service because the location can affect what it senses. Larsen’s page on programmable thermostat service explains the control options if the thermostat itself is unreliable or no longer fits the household.

5. Reduce the heat the AC has to remove

AC preparation is partly equipment care and partly building care. Before the heat wave, check that frequently used exterior doors close fully, window locks pull sashes together, and obvious gaps are not letting hot air pour in. Close blinds or shades before direct sun reaches the glass, especially on west- and south-facing windows. If safe and practical, delay oven use, long dryer cycles, and other heat-producing tasks until a cooler part of the day.

Keep windows and exterior doors closed while the AC is operating. Use ceiling or portable fans to improve how occupants feel, but remember that a fan does not repair a cooling system or make an unsafe indoor temperature safe. Turn unnecessary lights and electronics off, and keep return-air paths open so cooled air can circulate back to the equipment.

Persistent hot rooms may point to duct leakage, insufficient insulation, solar gain, or an airflow imbalance rather than an AC that needs a lower thermostat setting. A maintenance and tune-up visit can identify equipment concerns, while a broader home assessment may be appropriate when comfort problems are limited to a particular floor or room.

6. Make a household heat plan, not just an AC plan

The National Weather Service heat-alert guidance treats an Extreme Heat Watch as a preparation signal: decide how outdoor activities will change and identify a cooling location if effective air conditioning is not available. Do this before the warning stage. Save the address and hours of a reliable air-conditioned place, arrange transportation if needed, and keep important phone numbers somewhere that does not depend on one person’s phone battery.

CDC guidance on heat and your health recommends staying cool, staying hydrated, knowing heat-illness symptoms, checking on people who live alone or have chronic medical conditions, and planning for refrigerated medicines or electronic medical devices during a power outage. Infants and young children, adults 65 and older, pregnant people, and people with certain heart, lung, or other chronic conditions may need added protection.

Decide who will check indoor conditions, who will contact a vulnerable relative or neighbor, where pets can cool down, and when the household will leave for the backup location. If anyone develops severe or worsening heat-illness symptoms, treat it as a health emergency; an HVAC appointment is not medical care.

7. Prepare for heat and wildfire smoke together

Utah heat can overlap with poor air quality. Before a smoke event, confirm that the HVAC filter fits snugly and keep a spare on hand. Learn whether your system has an outdoor-air intake and how its controls work; do not close dampers or change ventilation settings unless you understand the system and can do so safely.

The EPA’s current wildfire smoke and indoor air guidance says a MERV 13 filter, or the highest efficiency a system can accommodate, may help reduce fine particles. EPA also recommends knowing how to use recirculation when a system has a fresh-air intake and checking filters more often during heavy smoke. Compatibility matters: a filter that creates too much resistance can undermine airflow, so ask an HVAC professional if the allowable rating is unclear.

Warning signs to address before the heat wave

Preparation should reveal problems early, not encourage risky troubleshooting. Schedule AC repair before the hot stretch if you notice any of these changes:

  • Airflow is weaker than normal at most registers, even with a clean filter.
  • The system starts and stops repeatedly instead of completing normal cycles.
  • The outdoor unit does not run when the thermostat is calling for cooling.
  • The thermostat temperature rises steadily while the system runs.
  • Ice appears on a refrigerant line or near the indoor coil.
  • Water appears around the furnace, air handler, ceiling, or drain area.
  • A breaker trips, the system buzzes or grinds, or you smell burning or melting plastic.

Turn the system off and call for help when there is ice, water near electrical components, a burning smell, loud electrical buzzing, grinding, or a breaker that trips again after one reset. Do not keep restarting equipment to see whether the symptom disappears. Larsen’s guide to when an AC problem becomes urgent during extreme heat covers the failure-stage decisions without duplicating the preventive checklist here.

What a professional pre-wave check can cover

A homeowner can replace a filter and clear loose debris, but a complete cooling-system check requires tools and training. ENERGY STAR’s contractor checklist includes checking the starting cycle and controls, cleaning evaporator and condenser coils, inspecting condensate drainage, checking refrigerant level, and cleaning or adjusting blower components for proper airflow.

A good visit should end with a clear explanation of what was measured, what needs attention now, what can wait, and what symptoms to watch. Maintenance cannot guarantee that a component will never fail, but it can uncover existing problems before the system is asked to run through the most demanding days of the season.

How to operate the house during the hot stretch

  • Keep the thermostat on a stable, reasonable schedule and avoid repeatedly switching the system off and on.
  • Close shades before direct sun enters and keep exterior doors and windows closed while cooling.
  • Keep supply registers and return grilles open, and leave space around the outdoor unit.
  • Use fans for occupant comfort and turn them off in empty rooms.
  • Watch for a new change in sound, airflow, cycle length, water, ice, or breaker behavior.
  • Check the filter sooner than usual if wildfire smoke or unusual dust is present.
  • Follow the household heat plan if indoor conditions become unsafe or someone is at higher risk.

Frequently asked questions

When should I prepare my AC for a heat wave?

Begin when an extended hot spell appears in the forecast, and treat an Extreme Heat Watch as the prompt to finish the checklist. Testing before peak heat gives you time to schedule service, obtain the correct filter, and make a backup cooling plan.

Can I clean the outdoor AC unit myself?

You can safely remove loose debris from the surrounding ground and trim vegetation with the equipment off. Leave panel removal, coil washing, bent-fin work, electrical testing, and refrigerant work to a qualified technician.

Should I install a MERV 13 filter before a smoky heat wave?

Only if the filter slot and blower can accommodate it. EPA recommends MERV 13 or the highest efficiency compatible with the system, but higher resistance can reduce airflow in equipment not designed for it. Verify the equipment guidance or ask a technician.

What if the AC runs but cannot hold the set point?

Check the filter, thermostat settings, open registers, return-air obstructions, and outdoor-unit surroundings. If the indoor temperature continues to rise, airflow is weak, the system runs continuously, or warning signs appear, schedule professional diagnosis rather than driving the thermostat lower.

Who should I call if the test run reveals a problem?

Larsen Heating & Air can diagnose cooling problems for homeowners looking for AC repair in Saratoga Springs and Utah County. Share the symptoms and timing you observed so the technician has a useful starting point.

Prepare before the system is under maximum strain

The useful work is simple: run a normal test cycle, restore airflow, clear the condenser’s surroundings, confirm the thermostat, reduce avoidable heat gain, and make a household backup plan. If the test exposes a problem, address it before the heat wave rather than waiting for a no-cool emergency. That is the difference between preventive preparation and crisis response.