'91 Camaro - Electric Fan Control

[Shannen Durphey]

Similar statements are true about earlier F cars.  Any secondary cooling fan is
controlled by a temp switch in the rear of the RH head.
Shannen

Timothy J Burgess wrote:
> 
> As Denis mentioned, the '90 - '92 F-body ECMs control only the primary
> cooling fan, even though Tuner Cat displays turn on & turn off temperatures
> for both fans.  The secondary cooling fan is controlled by the temperature
> switch located in the passenger side cylinder head, with a turn on
> temperature of 238 F, and is ORed with a pressure switch in the A/C liquid
> line that closes when the R-12 pressure exceeds 232 psig.  The primary
> cooling fan is controlled solely by the ECM, with a stock turn on
> temperature of 230 F if the A/C is off, and lower if the A/C is on, under
> certain conditions.
> 
> Tim Burgess
> 
> Ken Richardson wrote:
> 
> > Does anyone on this list have any experience working with '91 GM F-body
> > ECMs, specifically the fan on/off temperatures?
> >
> > Here's my problem. We installed a 383 stroker in a '91 Camaro and have
> been
> > burning EPROMs to correct the fuel mappings etc. Everything is working
> well
> > except I can't seem to get the fans to turn on and off when I want them
> to.
> > The first thing that happened is the fans reversed, Fan #2 was coming on
> > first, then Fan #1. They were coming on around 210 degrees even when I
> set
> > them to 180 and 200 respecively. Then I burned an EPROM with both fans
> set
> > to 190....now Fan #1 doesn't come on at all and fan #2 comes on at 210.
> >
> > I'm using the Tuner CAT program to modify my EPROMs. Could this be my
> > problem? Ideas? Does anyone have a wiring diagram of the fan circuitry?
> >
> > Thanks
> > Ken R.
> 
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