How to troubleshoot fan power supply faults on an ACRC, ACRD, ACDA, and ACSC.

All Product models, all serial numbers.

Cause:
Power Supply fault.

Resolution:
Should you need to troubleshoot the 48V power supply for a failure, please know, the Fan Power Supply Fault occurs when the power supply output is at least 1 amp less than the output of all of the other power supplies in the unit.  This occurs when the fans are commanded on and the power supply output is less than 200mA.  If a single power supply fails, the controller will limit the maximum fan speed to 70%.  The location of the fan power supplies differ depending on the model#.    When a power supply fails you will need to know this location based on the unit in question.  Also, the alarm may report Left Fan Power Supply Fault or Right Power Supply Fault on an ACRC or ACSC.  Whereas, on an ACRD the power supply failure will read Upper or Lower Fan Power Supply Fault.

Rectifier LED indicators:

● Over-voltage LED: When red, rectifier DC output voltage is above 57 Vdc (must be powered down to reset)

● Current limit LED: When red, rectifier is at current limit

● Input healthy LED: When green, AC power is present

● Output healthy LED: When green, rectifier DC output voltage is 39.5-59.5 Vdc (set for 48 Vdc nominal)

The new power supplies ship in all ACRC1xx YK0844xxxxxx, ACSC100/101 YK0815xxxxxx, and all ACRDs.

A new DC power supply from a new manufacturer has been introduced into production, replacing the previous power supply. The new part has a unique part number (W920-0082) and can be visually identified as shown and noted later in this bulletin. The new part is removed and installed in the same manner as before.

The only requirement is that the old and new design power supplies are not to be intermixed in the same unit. That is, use in pairs of old or new, but not one of each.

Use the schematics to help you troubleshoot the failures if reseating and swapping the power supplies fail indicating the failure is beyond the power supply.

Tools
#2 Standard or Phillips screwdriver; T30 Torx screwdriver [ACSC only]

The individual power supplies can be replaced without removing power from the unit.  For safety reasons, remove power whenever possible. If you must swap power supplies while the unit is receiving power, take appropriate safety precautions to avoid moving parts and live electrical components.

Replacement (ACRC)

1. Remove power to the unit by disconnecting power cord(s).
2. Lockout/tagout the unit being serviced.
3. Remove the rear door and the bottom air filter.
4. Loosen the two screws at the top and bottom of the right side of the face of the power supply you want to replace.
5. Loosen the screws just enough to remove the power supply, do not remove them from the face plate of the power supply.
6. Pull the handles to slide the power supply out towards you.
7. Reverse the procedure to install the new power supply.
8. Use a standard screwdriver to tighten screws to 4–5 in·lb (.5–.6 N·m).
9. Verify operation of the power supply (the fan speed should return to 100%).

Replacement (ACSC) will need T30 Torx screwdriver [ACSC only]

1. Remove the front door, display interface, and front panel.
2. Loosen the two screws at the top and bottom of the right side of the face of the power supply you want to replace.
3. a. Caution: Loosen the screws enough to remove the power supply. Do not remove them from the face plate
4. of the power supply. Pull the handles to slide the power supply out toward you.

3. Reverse the procedure to install the new power supply.
4. Tighten screws to 0.5–0.6 N·m (4–5 in·lb).
5. Reinstall the front door, display interface, and front panel.
6. Verify operation of the power supply. You should be able to make the evaporator fans run at 100%.
7. Verify LED operation on the front of the power supply.

Replacement (ACRD)

1. Perform the safety and power removal tasks
2. The DC rectifiers can be removed with the power panel inside or outside of the unit.
3. Loosen two screws.
4. Pull the DC rectifier straight out of the power panel.

Caution: Two different power supplies are available for this unit. One type has holes in the metal faceplate in front of the fan, as shown. The other type has a wire guard over the fan.  Either type will work, but both power supplies must be the same, or improper operation will result.

NOTE: The power supplies with Schneider Electric branding are not compatible with either of the older style power supplies, and also require an upgrade to the R2 SIMM card.

ACRD - Located on the rear slide tray [upper and lower power supply]

ACRC - Located in the rear bottom

ACSC

Located in the front behind the display and front panel




ACDA

Released for:APC USA