AC failures and improper operation

Improper installation is a common cause of malfunction of central air conditioners (AC). Faulty installation involves, namely, the AC refrigerant charge, ducts and low airflow.

Open windows, doors and AC failures

Leaky homes and open windows and doors can be causes of AC improper operation. When operating your air conditioner, be sure your home's windows and outside doors are closed. For room air conditioners you should isolate – as much as possible - the room or rooms being cooled from the rest of the home.

Inadequate maintenance

Inadequate maintenance and poor professional AC service involving refrigerant charging, coil cleaning or AC airflow may cause malfunction and failures in your AC equipment. Maintenance is very important, namely replacement or cleaning of filters, and coils and blower cleaning. A very dirty filter can easily cause your air conditioner unit to shut down due to inadequate airflow.

See:

Maintenance
Professional Technician Services
AC filters
Refrigerant charge
Outdoor Coils Cleaning
Indoor Coils Cleaning
Blower Cleaning
Room air conditioner maintenance

Fuses and circuit breakers

In case of failing, check the air conditioner’s circuit breakers and fuses. Before resetting the breakers, let the unit cool down for some few minutes.

Compressor

If your central air conditioner's compressor stops, check the high-pressure limit switch. It may have tripped; reset it by pushing the correspondent button.

Electric Control Failure

Corrosion of wire and terminals are common, and a cause of AC failures. Electrical connections and contacts may also be damaged due to overuse and strain, especially if the air conditioner is oversized (a common situation) and turns on and off too frequently.

Sensor Problems

If your room air conditioner behaves erratically or cycles constantly, inspect the thermostat sensor (usually located in the control panel). See if it is well positioned. The sensor should be near the coil, but without touching it; if it doesn't, adjust its position by carefully adjusting the correspondent wire.

Drainage Problems

Check the condensate drain. See if it isn't clogged and draining improperly. This is very common in room air conditioners, whenever mounted unlevel.

On/Off switches and button positions

In case of failure, make sure that…

- the condenser is running: check the circuit breakers and see if they are in the "On" position;
- the disconnect switch of the condenser is in the "On" position;
- the blower motor is running and its on/off switch is in the "On" position;
- the return air grilles are not blocked by furniture;
- the supply air registers (typically located on walls) are open and blowing air;
- the thermostat is set in the "cool" position.