Rheem RHMV2421MNACJA Service Manual page 59

Troubleshooting 4
External communication error
Detective actuators:
External communication error
Detective details:
After receiving signal from external I/O PCB,
the same signal has not been received
for 15 seconds
Forecast of cause :
1. Connection failure
2. External I/O PCB failure
3. Controller PCB failure
Check Point 1 : Check connection
Check any loose or removed connection of between the controller PCB to the external I/OPCB
>>If there is an abnormal condition, correct it by refer to installation manual or
the technical manual.
Check the connection condtion on the external I/O PCB and the controller PCB
(If there is loose connector, open cable or mis-wiring)
OK OK
Check Point 2: Replace external I/O PCB
If Check Point 1 do not improve the symptom, change external I/O PCB.
OK OK
Check Point 3: Replace controller PCB
If Check Point 2 do not improve the symptom, change Controller PCB.
Indicate or Display:
Indoor unit
Operation lamp: 1 times Flash,
Timer lamp
Wired remote control
Error code : [E : 18]
Outdoor unit (RP1736/1748HJVXA)
Mode Error
2
: Light OFF
03-09
: 8 times Flash
A B C D E
5 15
: Light ON n : n times blinking
F