Service call performed today. Checked system operations, checked 240 at AH and CU, 24v at AH Transformer and at CU Contactor, amp draws within range, air filters recently replaced by client, uv bulb due for replacement 3/2024, thermostat set to run fan 24/7, educated client that fan should be set to “auto”, client has difficulty seeing thermostat numbers, recommend upgrading thermostat to newer model, client also mentioned return grills whistling, recommend replacing return ductwork with larger duct runs to resolve whistling. System operations normal.