Fujitsu 76 2-Way / 3-Way Valve Thermistor Error
Feb 20, 2026
119
2-Way / 3-Way Valve Thermistor Error
2-Way / 3-Way Valve Thermistor error codes by model:
7x Operation & 6x Timer flash:
ASU7RLF1, ASU9RLF1, ASU12RLF1, ASU18RLF, ASU15RLS, ASU15RLS2, ASU15RLF1, ASU24RLF, ASUH07LPAS, ASUH09LPAS, ASUH12LPAS, ASUH15LPAS, ASUH18LPAS, ASUH24LPAS, ARU7RLF, ARU9RLF, ARU12RLF, ARU18RLF, ARU24RLF, ADUH07LUAS1, ADUH09LUAS1, ADUH12LUAS1, ADUH18LUAS1, ADUH24LUAS1, AUU7RLF, AUU9RLF, AUU12RLF, AUU18RLF, ACUH07LUAS1, ACUH09LUAS1, ACUH12LUAS1, ACUH18LUAS1, AGU9RLF, AGU12RLF & AGU15RLF
3x Operation & 2x Air Clean / 3x Operation & 3x Air Clean flash:
ASU9RMLQ, ASU12RMLQ, ASU18RMLQ, ARU9RML, ARU12RML, ARU18RML, AUU9RML, AUU12RML & AUU18RML
5 flashes LED 1 / 5 flashes LED 2 / 5 flashes LED 3 / 6 flashes LED 1 / 6 flashes LED2 / 6x flashes LED 3 / 6x flashes LED 4:
AOU18RLXFZ, AOU18RLXFZH, AOU24RLXFZ, AOU24RLXFZH, AOU36RLXFZ, AOU36RLXFZ1, AOU24RML, AOU24RML1, AOU36RML & AOU36RML1
76 / 1D / 1E Wired remote:
UTY-RNNUM, UTY-RVNUM, UTY-RSNUM, UTY-RNRUZ Series, UTY-RSNUM, UTY-RSRY, UTY-RHRY
SERVICE TIP:
This issue may not bring on a code. The code usually comes up because there is a short or open in the thermistor pack. When the thermistor is reading way off it may cause the outdoor unit to not do anything while the indoor unit tries to run. This is a protection function.
2-Way / 3-Way Valve Thermistor Error Troubleshooting Checklist
- To begin, start by checking if the molex plug(s) are disconnected from the Main Control board. If connected, check to make sure it is securely fastened to the board tightly. All molex plugs make a snapping sound when properly inserted. Service Manuals contain all wiring schematics and diagrams for the model in question.
- If molex plug is properly inserted in board and error code is still flashing, the thermistors must be ohmed out with a quality ohm meter. Reference attached 2017 Troubleshooting Guide for proper ohm resistance readings. If the readings are good, there is a high likelihood the Main Control board would need to be replaced.
- If the thermistor does not ohm within proper resistance values replace it.
