T-363 7–36Figure 7.28 Return Sensor Positioning7.22 VENT POSITION SENSOR (VPS)The vent position sensor (VPS) determines the position of the fresh air vent in near real-time via the Cd45.The fresh air VPS alarm (AL50) will occur if the sensor reading is not stable for five minutes or if the sensor is out-side of its valid range (shorted or open). This can occur if the vent is loose or the panel is defective. To confirm adefective panel, assure that the wing nut is secure and then power cycle the unit.The alarm should immediately go inactive. Check the four-minute stability requirement. If the alarm reoccurs afterthe four minutes and the panel was known to have been stable, then the panel should be replaced.If the alarm immediately reappears as active, the panel should be replaced.VPS:In order to replace the VPS, the panel must be removed and replaced with another upper fresh air panel equippedwith VPS.Upon installation, a new VPS assembly requires calibration as follows:1. Rotate the vent to the 0CMH/CFM position.2. Code select Cd45 will automatically be displayed. Press the Enter key and hold for five seconds.3. After the enter key has been pressed, the display will read CAL (for calibration).4. Press the ALT MODE key and hold for five seconds.5. After the calibration has been completed, Cd45 will display 0 CMH / CFM.7.23 EAUTOFRESH SERVICE7.23.1 Servicing the eAutoFresh Air FilterRemoving the Air Sample Filter ElementThe air sample filter element can be accessed in two ways:1. Through the eAutoFresh side evaporator access panel (see Figure 3.2).2. Through the inside of the container by lowering the upper evaporator panel.a. By hand, unscrew and remove the filter cup from the bottom of the air sample filter assembly.b. Remove the filter element from the filter assembly.c. Install the new air sample filter element by reversing the above steps.Evaporator GrilleCombinationSensor (Mount inEither Clamp)MountingClampSeal
