Commercial service call in Euless and Upon arrival found Ortiz three somewhat cooling. Checked RTU three and found first stage slightly low on refrigerant. Added 3 pounds of 410 A to circuit one. Supply temperature is 55° return temperature is 74°. System is operating properly at this time. System does have two duct detectors with one being tied into the unit and one separate for the fire alarm. There seems to be an issue on the fire alarm side. Recommend getting fire alarm company out to check for proper operation.