If an air conditioner continues to blow air even after the thermostat has shut off and there is no coolant (refrigerant) in it, there could be several possible reasons for this behavior:
Fan-only mode: Many air conditioning systems have a "fan-only" mode that allows the fan to continue running without the compressor (cooling component) operating. This setting is used to circulate air throughout the room without providing cooling. If your AC is set to fan-only mode, it will continue to blow air without cooling.
Delayed fan shutdown: Some air conditioners are designed to have a delay in shutting off the fan after the compressor stops. This feature ensures that any remaining cool air in the system is distributed before the fan turns off. The delay may last for a few seconds to a minute.
Thermostat settings: Check your thermostat settings to ensure that the fan is not set to run continuously. Some thermostats have an "on" setting that keeps the fan running continuously, even when the cooling is not active. Change the setting to "auto" so that the fan only runs when the cooling system is actively working.
Faulty thermostat or control board: A malfunctioning thermostat or control board could cause the fan to run continuously, even when it should be off. The thermostat might not be accurately sensing the temperature, leading to incorrect fan operation.
Stuck relay or contactor: Within the AC unit, there are electrical components like relays and contactors that control the operation of the fan and compressor. If one of these components becomes stuck in the "on" position, it could keep the fan running even when it's not supposed to.
Wiring issues: Faulty or damaged wiring can cause electrical signals to be misinterpreted, resulting in the fan continuing to run incorrectly.
Defective fan motor: A malfunctioning fan motor could lead to continuous operation, as the motor fails to receive the signal to stop.
If you are experiencing this issue, it's essential to address it promptly to prevent unnecessary energy consumption and potential damage to the AC unit. It's recommended to have a qualified HVAC technician inspect and diagnose the problem to ensure a safe and proper resolution. They can identify the specific cause and perform the necessary repairs to restore proper functionality to your air conditioning system.