Specifications
Power Mac G5 (Late 2005) Troubleshooting — Symptom Charts 148
Fans
Individual fan failure
Replace fan
Exception: The media blower located between the optical and hard drives cannot be
replaced. You must replace the enclosure for this part.
Replace logic board
All fans run at high speed
Check for proper ventilation around the exterior of the computer.
Check that the clear plastic air deector is in place.
Run Apple Service Diagnostic (refer to “Thermal Calibration” earlier in this chapter).
Processor fans run at high speed
Verify that the clear plastic air deector door is in place.
Verify that the white sensor label is not damaged and is in place on the lower right tab of
the air deector door. If necessary, replace the air deector.
Verify that the air deector sensor board is operating properly.
Note: You can dierentiate a bad sensor label from a bad sensor board by the following:
Remove the air deector door. Slide a folded piece of paper through the slot in the enclosure
where the right tab of the air deector would normally be inserted. If the red LED goes out
(but stays on with the door in place), the sensor label on the door is missing or damaged.
Check the sensor cable connection on the logic board (second from right connector located
directly below the hard drives).
Replace the logic board.
Replace the air deector sensor board.
Computer goes to sleep for no apparent reason
Two additional symptoms: The system log typically includes a message similar to: “PowerMac7,3
Thermal Manager: Thermal Runaway Detected: System Will Sleep.” The customer may also note
that the fans ramp up to a higher speed shortly before the computer sleeps.
Check that the fans are operating.
If the system log still reports Thermal Runaway, run Apple Service Diagnostic (refer to
“Thermal Calibration” earlier in this chapter).
Replace the processor module.
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