Southern Comfort

Living in Las Vegas in the summer, road temps reach about 180 -200 degrees and keeping the beast cool in traffic or even on the highway is tough.
Temps run as high as 240 with A/C on.

I know the cooling problems have been beat to death here lately, and frankly i hate asking these questions cause I have tried to glean this information from previous posts...but here goes.

1. would a manual fan switch or a new lower temp switch (200 F) be more desireable?
2. Does the main fan ALWAYS work when the A/C is on and when does the Aux fan kick in?
3. Can the fan motor be damaged by running at highway speed with juice to the motor ie not turning off the man. switch?

:reddevil

vader86

I would do the lower temp switch, it'll catch things in case you get preoccupied. A manual switch is great for the drag racers who spend alot of time idling in the lanes. I dont really think you can go wrong with either.

The main fan should be on anytime the AC is on, and the secondary fan comes on if youre lower than 55mph with the AC on or if temps go higher than 235F, although I think that last fact with the AC might vary from early to late L98s. My AC doesnt work right now, so i cant test it.

Its detrimental to cooling if you have the fans staying on all the time. Over 55mph they actually hurt, the regular airflow at these speeds is greater.

scorp508

Is it 55mph? I thought it was 35mph. I would get the lower T-Stat and switch. I have those and a manual fan switch and I only use the switch in the staging lanes of a drag strip.

vader86

I couldnt remember if it was 35 or 55 either, i looked in the Haynes manual i have handy, and it said 55. So i went with that.

Ray Quayle

vader86,
In another post you said This is correct, it is controlled only by the switch in the head. So I've got a question for you; how does the switch know how fast you're going? No prize, it's just for fun!

scorp508

This is one of the Eternal C4 debates. I always mean to go look at the wiring and see how it works or if it was just for the '84 model year. There is a relay for the auxilary fan and I have a hunch that the ECM may kill the 12v supply if over a certain MPH.

65Z01

I agree, the lower themp fan switch is better for daily driving than the manual switch.

Since you have an aux fan, just install a lower temp aux fan switch along with matching t-stat and wire that switch to also bring on the main fan (see my C4 tech note on this). Along with the new switch & t-stat, this mod only takes two pairs of crimp connectors and a short piece of #22 wire. Then the ECM can still bring on the fans if required by other factors.

The ECM brings the main fan on when the A/C pressure exceeds a certain value (or when coolant temp rises above the programmed value) but not always when the A/C runs.

I've been running my fans per the above mod for several years and no damage to date. Since the switch & t-stat are 160deg F, the fans run at highway speeds in hot weather.

Southern Comfort

THANKS this clears up my questions...now on to more expensive mods...lol :seeya

Wheelman

do you think adding an earlier temp switch to the fan would cause the fan to be on constantly in 90-100 degree weather like we have frequently down here in Texas?? :confused:

vader86

Its 'turn on' setting isnt controlled by the ECM, temperature wise. No chip reprogram will make the aux fan come on sooner. The wiring diagrams show it as being tied into the ECM somehow though, which makes it clear as mud.

vader86

It will cycle on and off constantly if you drive in town, once it gets warmed up.

Wheelman

as long as they dont stay on all the time and still go off on the freeway i guess ill be alright..... :steering:


[Modified by Wheelman, 4:23 PM 7/3/2003]

Southern Comfort

my problem is that even on the freeway midday around here I runn about 205-215 dependant of outside air temp. I assume the with low temp switch the fan would be running unless the 55 mph rule kicks in....(i want my slide rule back) :eek:

65Z01

Especially in such a climate I would run a lower temp stat & matching aux fan switch. If you don't want to go to a 160 deg try a 170 deg stat & switch.

Ray Quayle

Can you direct me to the location of the wiring diagrams that show the Aux Fan tied into the ECM? If you are referring the the GM Manual for 1986 Corvette (ST-364-86), you may want to look at the Supplement (ST-364-86S). There are many errors in the original manual, some are corrected in the Supplement. My '86 GM manual doesn't even show the Aux Fan.

Ray Quayle

There is a relay for the aux fan, that is correct. That relays power is tied to the primary fan power at C100 and goes through the same Coolant Fan Fuse. That fuse is always hot in run. The switched part of the relay is tied directly to the Aux Fan Motor on pin A and directly to the Battery through a Fusible Link on pin E.

Not talking about the '84 here. I have no direct knowledge of the '84 except that I believe there is no computer control of the fan at all on the '84.

oldace84

Sent you an IM....................
TONY
:smash: :smash: :smash:

jtfrog

lower temp switch, Think of it as set it and forget it