I too prefer to use the three relay parallel/series control on two fans (where both fans are run together low speed or high speed but never individually) but you need to be careful what fans you use for this. Some fan motors don't work well at half voltage (get close to or drop below motor stall speed/torque). Also some fans won't be fuse protected in that configuration (you can stop the blade and fail the motor without blowing the fuse). If you are going to run the series/parallel configuration the easiest is to just use fans that are run that way from the factory (plenty of GM examples to choose from between Camaros, Corvettes, CK trucks etc.).
BTW - if you are running one fan you can also have two speeds with most GM PCM,s/ECMs using a two speed fan relay. Volvo has one that takes two inputs and switches a single fan from low to high speed.
Volvo Cooling Fan 2 Speed Relay, Volvo OE part numbers (used in lots of Volvos so cheap at the junk yard):
Kaehler also manufactures a part that is similiar to the Volvo Cooling Fan Relay. The part number is:
Quote:
Originally Posted by mikels
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If using the discrete outputs with dual electric, I prefer to set them as parallel / series control rather than have each fan driven by output. That way on 50%, you are driving both fans @ 50% rather than one @ 100%.
I hate listening to noisy fan(s) masking sound of engine - exception being when in track usage - where you NEED the fan output.
Dave
BTW - reason E40 & E67 were used in TBSS and H3 is vehicle communication was still Class 2 while Powertrain was CAN - E40 & E67 can handle both (E38 is CAN only).
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