Carrier bryant Multi-Zone 38MARBQ09 18AA3 Series Service Manual page 8

All Models
Indoor Outdoor Unit Communication Error E1 (page 2 of 3)
Under normal operation voltage will alternate from approximately -50 Volts to +50 Volts.
If your meter has a MIN/MAX setting, we recommend using this. It can quickly show you the
top and bottom of the alternating range.
Follow the "1st Steps for DLS Troubleshooting" in the beginning of this guide,
Go to ODU and Measure the DC
voltage between "N/L2/2" and "S/3"
Black Lead to N/L2/2, Red Lead to S/3
The value is alternative from negative to positive.
The value is fixed and close to 0.
The value is always positive.
Check the wiring connection from outdoor terminal to outdoor
PCB and wiring between PCB's if there is more than 1 PCB
For ODU's with 2 PCB's,
main and IPM (Inverter).
if E1 is displayed, procedure below.
Note: Terminals may be referred to in one of three ways.
L, N, S Or L1, L2, S Or 1, 2, 3
Check the wiring connection
from indoor terminal to indoor
PCB. Are they OK?
Replace Indoor PCB.
No
For ODU's with only 1 PCB
Continued on next page