Trane TVR Pro CO Series Service Manual page 60

2.3 E2: Communication error between indoor and master unit
Digital display output
Description
 Communication error between indoor and master unit.
 All units stop running.
 Error code is only displayed on the master unit.
Trigger / recover condition
 Trigger condition: Indoor units and outdoor units cannot communication for 2 minutes after the system power on 20
minutes.
 Recover condition: Communication go back to normal.
 Reset method: Resume automatically.
Possible causes
 Communication wires between indoor and outdoor units not connected properly.
 Indoor unit power supply abnormal.
 Loosened wiring within electric control box.
 Interference from high voltage wires or other sources of electromagnetic radiation.
 Communication wire too long.
 Damaged main PCB or electric control box communication terminals block.
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