Carrier bryant Multi-Zone 38MARBQ09 18AA3 Series Service Manual page 28

All Single Zone Outdoor Units
Inverter Compressor Drive Error P4
Error Code
Indoor Unit or Wired Control Display – P4
Malfunction decision conditions
Supposed Causes
Troubleshooting:
Follow the "1st Steps for DLS Troubleshooting"
in the beginning of this guide, if you have an
active error, procedure below.
Check if the wiring between the main PCB
and the compressor are connected
incorrectly and if the wires or connectors are
broken. Were any connections loose or off?
Meg & Ohm the compressor, see
Compressor Checks 1 & 2.
Did Compressor Meg out correctly?
Error is only displayed every 3 minutes, during this time you may
see either "normal display" or "88" on indoor unit or wired control.
No
No
Replace both compressor & the IPM
(Inverter) board OR replace the
main PCB if the IPM board and the
main PCB are integrated together.
P4 – Compressor and/or Inverter Problem
Dr. Smart Display (Debugger) – P4, P43
An abnormal inverter compressor drive is detected
by a special detection circuit, including
communication signal detection, voltage detection
and compressor rotation speed signal detection.
• Wiring mistake
• IPM malfunction
• Outdoor fan assembly fault
• Compressor malfunction
• Outdoor PCB faulty
Dr. Smart
Display
Yes
Correct the connections or
replace the wires and connectors.
Replace the IPM (Inverter) board
Yes
OR replace the main PCB if the
IPM board and the main PCB are
integrated together.
If after parts
replacement, P4 is still
displayed, contact your
local CE Technical
Support Rep.