Troubleshooting - VAL - MCU Cassette Door Failure

Applies to	VLF Trendsetter AL

Machines affected	Machines with serial number lower than 20.

Error Number	None

Component	MCU

Problem	After closing the cassette door, the firmware relays an error message that the door is not closed.

Causes and Solutions	Cause: The sliding door assembly is mounted on an exterior panel, shown in pic 1 (front) and 2 (back). See photos below. Disassemble one side of the door lifting mechanism, shown in pic 3 assembled, and pic 4 disassembled. Lift the door up and towards the disassembled side of the unit (pic 5) to reveal the source of the problem, pic 6. There are usually three of these pieces of ~0.03" UHMW tape used to provide a wear surface for the door to freely move up and down. The problem is that when the thicker tape was used, it would initially conform to the bent panel, providing both a vertical wear strip and a bearing surface for the door to rest on while in the closed position. In time, the top surface of the tape lost its adhesion to the panel and began to separate, pic 6. The tape then acts as a spring, holding the door just open enough to trip the sensor. Solution: Using an exacto knife, cut the tape at ~30 degrees below horizontal (shown in pic 7) while running the blade along the bent surface of the panel. Try to minimize the amount of tape on the bent portion of the panel. Cut another strip about 1/2" wide UHMW tape and place it on the top surface to provide a separate bearing surface. If the tape looks bad, remove it all, clean the surface, and replace with new tape strips as shown in pic 8.

Causes and Solutions

Cause:
The sliding door assembly is mounted on an exterior panel, shown in pic 1 (front) and 2 (back). See photos below.

Disassemble one side of the door lifting mechanism, shown in pic 3 assembled, and pic 4 disassembled.
Lift the door up and towards the disassembled side of the unit (pic 5) to reveal the source of the problem, pic 6. There are usually three of these pieces of ~0.03" UHMW tape used to provide a wear surface for the door to freely move up and down. The problem is that when the thicker tape was used, it would initially conform to the bent panel, providing both a vertical wear strip and a bearing surface for the door to rest on while in the closed position. In time, the top surface of the tape lost its adhesion to the panel and began to separate, pic 6. The tape then acts as a spring, holding the door just open enough to trip the sensor.

Solution:

Using an exacto knife, cut the tape at ~30 degrees below horizontal (shown in pic 7) while running the blade along the bent surface of the panel. Try to minimize the amount of tape on the bent portion of the panel.
Cut another strip about 1/2" wide UHMW tape and place it on the top surface to provide a separate bearing surface. If the tape looks bad, remove it all, clean the surface, and replace with new tape strips as shown in pic 8.

Abnormal Engine Vibration