The temperature of the air coming out of the vents will depend on several factors, including the specific design and efficiency of your HVAC system, the outdoor temperature, and the condition of your ductwork. However, as a general guideline, you can expect the air coming out of the vents to be around 15 to 20 degrees Fahrenheit (8 to 11 degrees Celsius) cooler than the temperature set on your thermostat.
So, if you set your thermostat at 74 degrees Fahrenheit (23 degrees Celsius), the air coming out of the vents would typically be around 54 to 59 degrees Fahrenheit (12 to 15 degrees Celsius). Keep in mind that these are approximate values, and there can be variations based on the factors mentioned earlier.
If you notice significant differences in the temperature of the air coming out of the vents compared to what you expect, it could indicate an issue with your HVAC system that may require professional attention, such as a refrigerant leak or airflow problem. In such cases, it's advisable to contact a qualified HVAC technician to assess and diagnose the problem.