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I have a C5 with the stock fan (dual fans pulling through the radiator). Are both fans supposed to be on at the same time? I have read that they are always supposed to be on together, but someone on the internet who claims to be an LS tuner says one fan is low output, and the other comes on for high output. I figure that both fans should always come on together, just at different speeds. To have the two fans come on at different times seems no better than the 80's optional aux fan setup..
From the factory service manual: The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph)
See the problem? Some people say that both fans are always on, just at different speeds, that the manual is referring to the actual settings while others seem to say the the manual means that the fans operate independently.
@Fawnseh In a C5, fans can run in Low or High Speed Modes, but in each case, both fans are supposed to run at the same time and at the same speed.
In Low Speed Mode fans are wired in series, with half the voltage applied to each one. In High Speed Mode they are wired in parallel, with full voltage to each one.
C5 stock fans
