Carrier 38VMH-1P Service Manual page 37

:
E2: COMMUNICATION ERROR BETWEEN INDOOR UNITS AND OUTDOOR UNIT
DEFINITION
Outdoor unit cannot communicate with indoor units.
POSSIBLE CAUSES
• Communication wires between ODU and IDUs are installed incorrectly.
• Communication wires between communication and main control board are installed incorrectly.
• Incorrect power supply for all IDUs.
• Damaged main control or communication board.
• Communication wiring over 3937 feet.
• External interference (e.g. electromagnetic).
A210278
Fig. 43 —E2 Troubleshooting Chart
NOTE: Make sure that the matched resistance has been connected in the last indoor unit.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
37