Fujitsu 99 Error (4 Way Valve Error)

Skylar Kaczanowski

Mar 22, 2025

4-Way Valve Error
This error is more than likely being produced by a bad expansion valve coil. Verify EEV is still good before troubleshooting the rest of the way.

4-Way valve error codes by model:

9x Operation & 9x Timer:

RL2 series, RLS3 series, RLS2 series, RLB/RLXB series, RLF series, RLF1 series, LUAS1 series, LMAS series, LZBS series, LZAS series, LPAS series, RGLX series, RLE series

5x Operation & 6x Timer:

RLS series, RLXS series, CQ series, RQ series, R2 series, RL series, RML series, RMLQ series, CLX series, CLX1 series, RLX series, RLXQ series, CL1 series, CL series, RLQ series

9 flashes on LED A, 9 flashes on LED B & 1 flash on LED F:

AOU36RLXFZH & AOU45RLXFZ

2 flashes on Power Mode LED, Solid Error LED, 9 flash L1, 9 flash L2, solid L5 & solid L6:

AOU30RLXEH

E991 outdoor LED:

AOU48RLXFZ & AOU48RLXFZ1

97 / 98 / 1B Wired remote:

UTY-RNBYU, UTY-RNNUM, UTY-RVNUM, UTY-RSNUM, UTY-DMMUM & UTY-RNRUZ series, UTY-RSRY, UTY-RHRY

4-Way Valve Error Troubleshooting Checklist

Pull disconnect for 5 minutes & reapply, if error code appears while in cooling mode and but the unit is not cooling then proceed with below troubleshooting. If after resetting the disconnect the unit comes on and cools, replace the indoor board and indoor thermistors and do not proceed further with any troubleshooting.
Check to confirm that the molex plug for the 4-way valve is secure to the Main Control board of the condenser. If the thermistor is secure to the condenser's Main Control board proceed to checking the pipe thermistor on the indoor unit for the same as the previous check.
If both thermistors are secure to their respective control boards next step is to ohm both thermistors out and see if they contain the proper resistance. See Fujitsu Thermistor Chart for proper readings. The mobile technician app has this.
Remove the molex connection for the solenoid coil and check it for resistance. The coil should ohm to about 1.4k-2.4k ohms. To locate the designation for the solenoid, reference the Service Manual for the model number in question as all Service Manuals contain wiring diagrams.
With a temperature gun, conduct a temperature difference check on the 4-way valve. If there is a big difference in temperature this means the valve is working properly. If the temperature of both sets of pipes are the same this could mean a defective valve, if valve is defective replace valve.
If the valve checks to be okay, conduct an AC voltage check on the valve itself. Check the wiring schematic for the location of the valve and check for the same AC voltage at the valve as the line voltage coming into the condenser. This check should be done with power on to the disconnect. Voltage should be a steady voltage anywhere between 187-253 vAC.
If voltage is not present during this test then the valve is not being energized and the Main Controller PCB would need replacing.