Abstract: A passive thermal control valve comprising a thermal actuator coupled to a valve body having first and second ports. The thermal actuator including an actuator body having an inner bore. An adjustment stop engages the actuator body. A cylinder is received within the actuator body inner bore and the cylinder has a cylinder bore open at one end. An actuator spring within the actuator body biases the cylinder towards the adjustment stop. An actuator rod is at least partially received within the cylinder and has first and second ends. At least a portion of the actuator rod is allowed to extend through the open cylinder bore. A sealing element forms a seal between the actuator rod and the cylinder and defines a sealed chamber within the cylinder. A thermal fluid is contained within the cylinder. A lever mechanism is connected to the valve body and includes a lever having a first end connected to the valve body. A valve spool is connected to a lever second end.