Troubleshooting 257Troubleshooting Enclosure Fan ModulesCAUTION: Many repairs may only be done by a certified service technician. Youshould only perform troubleshooting and simple repairs as authorized in yourproduct documentation, or as directed by the online or telephone service andsupport team. Damage due to servicing that is not authorized by Dell is not coveredby your warranty. Read and follow the safety instructions that came with theproduct.NOTE: The fan modules are hot-swappable. Remove and replace only one fanmodule at a time in a server enclosure that is turned on. Operating the systemwithout all three fan modules for extended periods of time can cause the system tooverheat. Review the following table before you begin to replace the fan modules.Fan Module (Fan Controller Firmware) Thermal Behavior Per SledTable 5-1. Fan Module (Fan Controller Firmware) Thermal Behavior Per SledFan ModuleStatusBMC (Processor/Memory)/Server Enclosure Temperature StatusOK/OK OK/Fail Fail/OK Fail/FailFan modulenormal/OKClose loop,Open loop (curve A)a,If the PWM dutycycle value rises above100%, sled-levelthrottling istriggered bClose loop,80% PWMIf close loopPWM signalvalue is > 80%,the PWMoutput willfollow the closeloop outputOpen loop (curve B)c,If the PWM dutycycle value rises above100%, sled-levelthrottling is triggeredb100% PWMOne fanmodule failsClose loop,If the PWM dutycycle value rises above100%, sled-levelthrottling is triggeredb100% PWM 100% PWMOpen loop(curve C)d,If the PWM dutycycle value rises above100%, sled-levelthrottling is triggeredb100% PWMSystemthrottling
