Q: What is the cooling fan system in Chevrolet Avalanche,Silverado,Suburban,Tahoe,GMC Sierra,Yukon,Yukon Denali and Yukon XL with two fans behind the radiator and how can it be diagnosed and repaired?
A: These models have two Radiator fan behind the radiator that are operated by the PCM and three relays to adjust the speed as needed. The fans are protected by fuses in the engine compartment's fuse/relay box. If the engine overheats and the Radiator fan don't work, check the fuses and fan motors. If the motors are okay but the fans still don't work, the relays may be defective. To remove the radiator fan/shroud assembly, disconnect the battery cable, drain the cooling system, remove the intake air duct and resonator assembly, and disconnect various hoses and electrical connectors. After cleaning debris from the shroud, install the fan motor mounting bolts and tighten them securely. Finally, refill the cooling system and check the transmission fluid level. If no obvious problems are found, have the radiator fan system diagnosed by a qualified repair shop.