Final answer:
To address the insufficient subcooling level, the technician should reduce the fan speed to potentially increase the condenser's heat retention and achieve the specified subcooling value. Other causes should be investigated if this does not resolve the issue.
Step-by-step explanation:
When dealing with an air conditioner that has a thermostatic expansion valve (TXV) and is operating with a condenser saturation temperature of 95 degrees Fahrenheit and a liquid line temperature of 92 degrees Fahrenheit, with a factory-specified subcooling of 10 degrees Fahrenheit, the appropriate action would be d) Reduce the fan speed. This is because the subcooling value is currently 3 degrees Fahrenheit (95ºF - 92ºF), which is less than the specified 10 degrees Fahrenheit. Adjusting the fan speed downwards may help increase the subcooling by allowing more time for the refrigerant to transfer its heat to the ambient air. Reducing the fan speed can potentially cause the condenser to retain more heat, thus potentially increasing subcooling to the desired level. It's important to note that if this does not correct the issue, the technician should further investigate other possible causes such as refrigerant charge, airflow issues, or blockages.