Phaser 4400 Laser Printer Service Manual 2-49Fuser Failure.(U4 Fuser Fail/Power Off) Low temperature trouble/Power off (Fuser temperature drops below the settemperature after the Fuser warm-up is complete.) Warm-up fail/Power off (Fuser warm-up does not complete within 110seconds.) STS Disconnection fail/Power off (Thermistor circuit is detected to beopen). High Temperature trouble/Power off (Fuser temperature rises above the settemperature.) Continuous heat on/Power off (Heat rod is on for 10 seconds when the MainDrive Motor is stopped, after the Fuser warm-up is completed.)Fan Failure; Power Off Now.(U5 Fan Fail/Power Off)The printer is detecting incorrect fan rotation.Fuser Failure Troubleshooting ProcedureStep Actions and Questions Yes No1 Switch the printer power OFF. Wait a few minutes, thenswitch the printer power-on.Does the error message reappear?Go to FuserAssembly onpage 3-18.Go to step 2.2 Run 25 to 30 test prints.Does the error message reappear?Go to FuserAssembly onpage 3-18.Problemsolved.Fan Failure Troubleshooting ProcedureStep Actions and Questions Yes No1 Switch the printer power OFF, then ON.Does the Fan rotate when the main power isswitched on?Go to step 4. Go to step 2.2 1. Switch the printer power OFF.2. Remove the Left Interface Cover (RRP 1.1,page 6-6), Left Cover (RRP 1.2, page 6-7), and LeftPlate (RRP 1.11, page 6-16).3. Switch the printer power-on.4. On the LVPS, check the voltage between P/J283 pin1 and frame ground.Is the voltage +19 ±1.9 VDC?Replace theFanAssembly(RRP 9.1 onpage 6-87).Go to step 3.3 Check the voltage between P/J281 pin 13 and frameground.Is the voltage +0.8 ±0.1VDC?Replace theLVPS (RRP9.5 onpage 6-91).Replace theEngine LogicBoard (RRP9.3 onpage 6-89).
