Keystone air conditioner fan runs continuously even when the compressor cycles off and the set temperature is reached.

Steps:

• Check fan setting: On the control panel or remote, set the fan mode to AUTO rather than HIGH/LOW/ON. In ON mode, the fan will run continuously by design.
• Observe behavior: In AUTO mode, the fan should cycle with the compressor or slow down when setpoint is reached.
• Relay check: If the fan continues at full speed in AUTO and with the unit turned OFF, the fan relay on the control board may be stuck closed and the board should be replaced.