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Pre-commissioning and Maintenance
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PRE-COMMISSIONING
1. Verify ALL indoor unit ON/OFF buttons are in the OFF position (i.e., on/off button NOT illuminated).
2. Check the terminations, polarity, and continuity of each conductor on the communications cable
between the water source unit and the indoor units. Verify the indoor unit to water source unit commu-
nications cable is wired correctly.
• Verify the conductor connected to the “3 (or “5” in the case of cassette frame codes TP, TN, TM)
terminals on all indoor units and is terminated on the water source unit terminal tagged IDU(A).
• In a similar fashion, verify the conductor connected to all indoor units on the “4” (or “6” in the case
of cassette chassis codes TP, TN, TM) terminals and is terminated on the water source unit terminal
tagged IDU(B).
3. Verify the shield of the communications cable is grounded at the water source unit only. All segment
shields should be spliced together at each indoor unit and NOT grounded.
4. After repairing the communications cable, go to Step 9 of the Initiate the Auto Addressing Procedure
and repeat the process until successful: Press and hold red Auto Address Button for about five (5)
seconds. Release when “88” appears on the LED. After three (3) to seven (7) minutes, the display will
flash a number for about ten (10) seconds indicating how many indoor units the system successfully
communicated with.
5. This number should match the known number of installed indoor units if the auto addressing
procedure was successful.
6. Upon completion of the auto addressing routine, the display will be blank and the system will be in
standby waiting for another command.
7. Record the system address the water source unit assigned to each indoor unit by the auto address
procedure in the column provided on the Pre-commissioning Device Configuration Worksheet.
8. After recording the system addresses assigned to each device, open the water source unit discon-
nect. Remove the water source unit to indoor unit communications cable from terminals IDU(A) and
IDU(B). Protect conductors by placing electrical tape over the bare ends to prevent an accidental
compressor start from occurring before the Commissioning Agent arrives.
9. Close the disconnect to reapply power to the water source unit and energize the compressor crank-
case heater. Once again, verify the water source unit to indoor unit(s) communications cable is not
connected to terminals IDU(A) and IDU(B) of the water source unit.
10. Replace the control panel cover.
Troubleshooting a Failed Indoor Unit Auto Addressing Procedure
If the quantity of indoor units the auto addressing procedure found is incorrect, or the “88” never disappears from the
display for the seven (7) minutes, the auto address routine has failed and a communications problem exists. If the Auto
Address Procedure failed:
Indoor Unit Auto Addressing
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