Rheem RHMV2421MNACJA Service Manual page 78

Troubleshooting 21
Outdoor temperature sensor error
Detective actuators:
Outdoor temperature thermistor
Detective details:
Outdoor temperature thermistor
short or open detected
Forecast of cause:
1. Connector connection defective, open
2. Thermistor failure
3. Main PCB failure
Check Point 1 : Check the connector connection and cable open
Connector connection state check
Cable open check
Check Point 2: Check the thermistor
Thermistor characteristics check (Disconnect the thermistor from the PCB and check.)
* For the thermistor characteristics, refer to the "Parts Information 7".
OK
Check Point 3 : Check voltage of main PCB (DC5.0V)
Main PCB (CN62:1-3) voltage value = 5V (RP1724/1730HJVXA)
Main PCB (CN61:1-3) voltage value = 5V (RP1736/1748HJVXA)
Remove thermistor from main PCB, and check voltage.
RP1724HJVXA
RP1730HJVXA
If voltage does not appear, replace main PCB,
and execute check operation again.
RP1736HJVXA
RP1748HJVXA
1 2 3
1 2 3
CN62
Indicate or Display:
Indoor unit
Operation lamp: 7 times Flash,
Timer lamp
Wired remote control
Error code : [E : 74]
Outdoor unit (RP1736/1748HJVXA)
Mode Error
2
: Light OFF
1 2 3
1 2 3
CN61
03-28
: 4 times Flash
A B C D E
7 4
: Light ON n : n times blinking
DC
F