YORK YLAA — Drive not responding

The panel shows Drive not responding. The manual prints the message in this single form — there are no other variants. It is the fault message belonging to the ABB AYK550 Variable Frequency Drive (VFD) installed on the air-cooled chiller; the service letter covering it lists the YLAA, YVAA and YVFA models.

The message reports a fault on the ABB AYK550 VFD of the chiller. When it appears, the manual points first to the drive's heatsink cooling fan, which may be jammed or failed, before the drive itself is suspected. Its procedure is built to confirm the fan before the VFD is condemned.

• The heatsink fan of the VFD is jammed or has failed — in this case the drive still powers up normally and only the fan needs replacing.
• A failure within the VFD itself: if the message persists after the heatsink fan has been checked, the manual concludes the drive has suffered other damage and must be replaced.

1. Before condemning the VFD, confirm that the heatsink fan has not failed.
2. Make sure the unit is deenergized and locked out before any of the work that follows, using JCI procedures for working on electrical equipment; the manual allows this work only for properly trained personnel who are qualified for this type of equipment.
3. Loosen the screws that hold the rain hood in place — keep the screws and the foam seal for reassembly — and remove the rain hood assembly; the heatsink fan sits on the back side of the VFD enclosure, behind this hood.
4. At the top of the VFD, pull the lever on the plastic fan grill guard so the guard and the fan rotate and lift out; do not pull it far, because its wire is attached inside the VFD.
5. Trace the fan wire and disconnect it where it plugs into the VFD.
6. Energize the unit and follow the chiller controls panel procedures to power the VFD.
7. If the drive powers up normally, showing voltage, amperage, and Hz on the screen, the fan has failed and needs replacing. Do not continue to run the VFD with the cooling fan disconnected — the VFD will overheat and fault.
8. Read the nameplate label on the side of the ABB VFD for its part number and voltage, and select the matching replacement fan: 026-52721-000 for the R1 & R2 frame, 026-52722-000 for the R2 & R3 frame, or 026-52723-000 for the R4 frame.
9. Take the faulty cooling fan out of the fan grill guard without damaging the retaining clips, connect the wiring to the new fan, and fit the grill guard with the fan back into the VFD.
10. Refit the rain hood with the screws removed earlier, checking that the foam seal is in good condition and properly compressed.
11. If the drive still shows the Drive not responding fault after this, the drive has other damage and must be replaced.