A manual-type HVAC system requires the operator to fully control all of the following EXCEPT: a. Direction. b. Velocity. c. Temperature d. Exterior temperature

## Step 1<br />A manual-type HVAC (Heating, Ventilating, and Air Conditioning) system is a type of heating and cooling system that is controlled by a human operator. The operator has control over several factors in this system.<br /><br />## Step 2<br />The operator can control the direction of airflow in the system. This is done by adjusting the direction of the air vents.<br /><br />## Step 3<br />The operator can also control the velocity of the airflow. This is done by adjusting the speed of the fan in the system.<br /><br />## Step 4<br />The operator can also control the temperature of the system. This is done by adjusting the thermostat, which controls the heating or cooling of the system.<br /><br />## Step 5<br />However, the operator does not have control over the exterior temperature. The exterior temperature is an external factor that cannot be controlled by the operator.