Hello,

Just an attempt to share some info.

Went by local GM dealership and looked at an 05 Chev. 1500 pickup.
Opened the hood and was checking out the electric fan setup.  
5.3 V-8.  Truck has two large electric fans mounted in their own
bracket that serves as a shroud too.  I did not look at the bottom
of the radiator but the fan bracket mounts to the top of the radiator
core support and I assume a similar setup on the bottom.

The two electric fans ands shroud cover the complete area of the
radiator core, so it appears that the fans draw air across the full
area of the core.  Did not see truck run, just checked it out.
(friends work there...) so had access to new truck, not yet prepped.

So anyway the fans looks to be a good setup, mount looks solid and
well designed. I roughly measure the core of the radiator and it looks
to be 19 * 34, so I would estimate the electric fans are around
14 to 16 inches (I did not measure those).

I was able to access some service manual information related to this.
System has three relays related to the radiator cooling fans, looks
like fans have 40 Amp fuses on the primary feed wires, and are setup
with a high and low speed. The PCM controls the operation of the fans.
One of the fan blades has 5 blades, the other 7 blades.

Low speed on the fans turns on at 202 F , High speed is enabled
when temp reaches 220 F.  Also fans come on at various A/C pressure
values.  Low speed fan will run for 1 min if temp is greater than 214F
after truck turned off, the fans will shut off at the 1 min mark if
temp drops below 214F, if temp does not drop fans will run for a max
of 3 min.

Overall looks like a good setup....will wait and see how it cools
during the summer months.  I assume the thermostat is a 195F. I still
don't  like the high coolant temps on the newer vehicles but I guess
that's the way it is.  I don't think it would be to hard to adapt the
fan setup from an 05 truck to an older model with the physical mounts.
I don't think it would be too hard to setup wiring and controls for
the fans since the 05 are controlled by the PCM, you would have to
resort to some aftermarket wiring. Painless and SPAL among others make
complete kits for electric fans. I did not that the SPAL item is fused
at 30 Amps while the GM factory setup is 40 Amps. Both use one relay
per fan, and the GM setup uses a third relay to control high and low
speed.

Another thing that I was not aware of is that the 05 GM pickups
(some of them) have something called a starter / generator control
module. Which to my understanding is basically a mini-radiator along
with the plumbing and its own electric fan (SGCM). I don't know if
this goes on all the trucks, but apparently there are water cooled
alternators and starters now....  

So anyway there you go...I have some illustrations of the parts if
anyone is interested.

Elbert
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Elbert Clarke
elbert.clarke@**adelphia.net
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