May 10, 2024
Why Is My AC Not Turning On?

Few things are as frustrating as arriving home on a warm summer day and realizing that your air conditioner is not turning on. In addition to feeling uncomfortable, you will likely be thinking about potentially expensive repairs or needing to replace your air conditioner completely. If your air conditioner is not turning on as it should, don’t panic. You don’t necessarily have an expensive repair or replacement in front of you. Before determining what might be troubling your air conditioner, it’s good to know how air conditioners work.

A Quick Breakdown of How Air Conditioners Work

Basic Parts

Most air conditioners include a thermostat that controls the temperature, indoor and outdoor coils used for heat transfer, copper tubing that enables refrigerant to travel between the indoor and outdoor unit, and an expansion valve to regulate the amount of refrigerant entering the evaporator coil. A central air conditioning system also features ductwork that allows conditioned air to travel throughout the home.

How It All Works

The thermostat is the central control for your air conditioner, overseeing indoor air temperature, detecting temperature shifts, and initiating cooling when necessary.

When the signal is received, the outdoor unit’s fan draws warm air from inside the house through return ducts. The air then passes through filters, which capture mold particles, dust, and debris.

Subsequently, the filtered warm air moves over the cooled evaporator coil, where the refrigerant absorbs heat, chilling the air. The blower then circulates this treated air through the home’s ductwork.

Meanwhile, the refrigerant travels to the compressor and outdoor unit. The compressor, functioning as a large electric pump, pressurizes the refrigerant before it moves to the outdoor condenser coil. Here, a fan pulls outdoor air through the coil, dissipating the heat energy extracted from the home and releasing it outside.

Throughout this cycle, the refrigerant undergoes cooling and liquefaction and returns indoors through another copper tube, passing through an expansion device to regulate its flow into the evaporator coil. The cooled liquid refrigerant then absorbs heat from indoor air, repeating the cycle.

Common Reasons Your Air Conditioner Won’t Turn On

Now that we have an overall picture of how an air conditioner works, we can better understand some factors that affect whether or not your air conditioner turns on.

Thermostat Issues

As mentioned, the thermostat serves as the brain of your air conditioning system, determining when to activate and deactivate it. A faulty thermostat could result in short cycling. This overworking can lead to sudden system failure, preventing the unit from functioning.

Another reason for your air conditioner not turning on could be a malfunctioning thermostat, a dead battery, or a blown breaker or fuse in the main electrical service panel. In homes with smokers, the thermostat wiring can accumulate dirt, soot, or cigarette smoke residue, affecting its operation. Even minor buildup on the thermostat’s mechanical or electrical components can disrupt its function.

During your annual HVAC maintenance, your HVAC professional should inspect your thermostat for any issues early on, preventing potential problems in the future.

Circuit Breaker Issue

If your AC isn’t turning on, check the circuit breaker. Circuit breakers can trip if you have too many appliances on the same circuit or a power surge after a storm. You will usually find the electrical panel in your garage or basement. Look for tripped breakers and flip the switch back on. If this doesn’t solve the issue or if tripped circuits are frequent, contact your HVAC professional immediately. Your air conditioner could be experiencing underlying electrical issues requiring professional resolution.

Condenser Issues

The condenser on your AC cools the refrigerant and condenses it into a warm liquid, which then enters the evaporator coil to expand and cool. Several moving and stationary parts must function in unison for this process to work.

If a part of your condenser unit is damaged or malfunctions, your air conditioning unit might not activate or respond. With window units, condensers commonly become unplugged. This can occur if the condenser cord disconnects from the unit or animals chew up wires. Improper connection of the condenser can interrupt the flow of electricity to your unit, preventing it from starting up.

Issues With the Filter

Dirty air filters can prevent an air conditioner from starting up. Your AC could also experience short cycling, where it turns on and off every few minutes throughout the day. Normally, the air conditioner should cycle on when the thermostat detects a temperature increase and then cycle off once the space is adequately cooled.

Clogged filters force the AC to work harder to push air through it, creating hot and cold spots throughout your home instead of maintaining an even temperature. Eventually, the strain on the air conditioner caused by the clogged filter can lead to system failure. This is because the unit can only sustain operating at twice the power for a limited time before breaking down. Something as simple as a dirty filter could result in costly air conditioning repairs or replacements, amounting to thousands of dollars. Scheduling regular maintenance by your AC technician is crucial, including checking and replacing the filters.

Power Switches Are Off

An air conditioner typically has an emergency shutoff switch located outside next to the AC unit. During home maintenance, someone may have intentionally or accidentally turned this switch off and left it in the off position. If the switch is off, the air conditioning unit will not function.

Additionally, there is an inside power switch for the HVAC system, resembling a light switch. If this switch is accidentally flipped off, your unit will not power on.

Icy Buildup on Components

Ice can form in your air conditioner if the temperature in the condenser or evaporator coil drops below freezing. This is often a sign that you have low refrigerant or a refrigerant leak. It can also occur if there are dirty coils, faulty wiring, a broken fan, or clogged air filters.

Troubleshooting Electrical Issues

If your conditioner isn’t turning on, check for potential issues with the low-voltage wires. These wires facilitate power flow from your home’s electrical system to the AC unit. Damage to the wires or disconnection could prevent the unit from starting up.

Examine the circuit control board. This board plays a crucial role in the AC system by monitoring the electricity flow to various components. If the board is damaged or malfunctions, your AC unit will not turn on.

Inspect the high-voltage wire. These wires transport electricity from the outdoor unit to the indoor unit. If they are damaged, your air conditioner will remain inactive regardless of how many times you attempt to switch it on.

Identifying and resolving electrical problems safely can pose challenges, underscoring the value of seeking assistance from a skilled professional.

Our HVAC Company Takes Care of Greenville, Wisconsin Homes

At Black-Haak, we have been committed to providing total residential and commercial comfort services since 1956. We proudly serve all of Fox Valley’s communities by offering our customers residential and commercial services.

Our services include HVAC installation, maintenance, and repair. We offer general plumbing and plumbing repair and install water heaters and water softeners. Our electrical services include generator installation and maintenance, general electrical repair, electrical wiring, and electrical panel installation. Contact Black-Haak today, and see for yourself why our service and technicians are so sought after.

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