Power issues: A tripped circuit breaker or blown fuse in your home's electrical system will prevent your AC from starting. Thermostat problems: Make sure you have your thermostat set to “cool” and the temperature is set below the current temperature in the room.
Check Your Circuit Breaker
Locate your main circuit breaker and switch it back to the "On" position. Wait 30 seconds and turn on your air conditioner again. If it still doesn't work, you'll need to call a professional for help.
In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.
Make sure it has power (check outlet if a window unit, check circuit breaker if hardwired). Check thermostat battery if accessible (some wall units use a battery). Check if filters are clogged. Check outside duct for obstructions.
To fix an AC not blowing cool air, ensure the thermostat is set to "cool" mode and the temperature is set lower than the current room temperature. Inspect the air filter as a dirty filter can restrict airflow. Ensure the condenser coils are clean and free of debris. Make sure vents are open and unobstructed.
Not all air conditioning units have a reset button, but if yours does, it's typically located on the outdoor unit. Here's how to locate it: Turn Off the Power: Before you search for the reset button, ensure the power to the unit is turned off for safety reasons.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.
An outside AC fan not spinning could be caused by power supply issues, a faulty capacitor, a burnt out motor, contactor issues, wiring problems, debris or obstruction, a faulty thermostat or control board, or frozen evaporator coils. Contact your local Carrier dealer to help troubleshoot the issue further.
There are a few reasons why this might happen. Some of the simpler causes may be that a vent is closed, or that the thermostat needs fixing. Some more major causes may be that the unit is low on refrigerant, signaling a leak, or that there is a problem with the fan.
Blowing the fuse cuts the power to the unit to prevent electrical damage. If your AC has shut down and won't start again, especially if you've noticed odd electrical behavior immediately before the shutdown, chances are the fuse has done its job and will need to be replaced.
Check the power source and make sure it is connected and turned on. Verify that the circuit breaker for the AC unit is not tripped. Make sure the thermostat is set to 'COOL' mode. Check the fan setting on the thermostat and ensure it is set to 'AUTO' rather than 'ON'.
Locate the breaker for your HVAC system, then flip it to the 'off' position. Wait a total of 30 seconds, then flip the breaker back to the 'on' position. Return to your thermostat, setting the mode to heat/cool and adjusting temperature settings, observing carefully for the flow of conditioned air.
Circuit breakers can be found in homes, businesses, and industrial facilities. They are typically located in the main electrical panel, which is typically located in the basement or garage.
When you notice that your air conditioner isn't cooling, your first action should be to turn it off. This might seem counterintuitive—after all, you want your home to be cool. However, continuing to run an AC that isn't effectively cooling can cause further damage to the system.
Check the air filter and replace the filter if it's dirty. Look for dirt clogging the condenser fins on the outside unit and clean the fins if necessary. Check for a clogged condensate drain line and clear the clog if condensate water isn't draining from the unit.
Reset the AC Using the Isolation Switch
The isolation switch looks like an ordinary light switch with a knob. Once you locate it, turn the knob to the off position and leave it for at least 30 minutes up to an hour. This will allow the electrically operated components in the AC to reset.
Make sure the outside unit is turned on (there's probably a switch near the unit). If the outside unit has a separate circuit breaker, check your circuit box and make sure it hasn't been tripped. A more serious issue if the outside air conditioning unit's not working is a broken compressor, capacitor or fan.
Water cooled systems (air conditioning without an outside unit) are plumbed directly into your water supply. They use the cold water in a controlled manner to cool the air through the piping system. Unlike traditional air conditioning systems, water cooled units do not require an outdoor unit.
The first thing you'll want to do is check the thermostat. If you have air that's controlled by a thermostat, make sure a faulty thermostat isn't what's causing the problem. In some cases, the batteries may have died or the unit is malfunctioning. Reset the thermostat to see if that turns the AC unit back on.
If your air conditioner isn't keeping up with the heat, your air filter may be to blame. A dirty air filter can obstruct the airflow path through the unit. Using a dirty air filter can also cause less energy efficiency and more costly utility bills.