Cooling Fans
Thread Starter
Advanced
Joined: Mar 2005
Posts: 68
Likes: 0
From: Plantation 1990 L98 383 Stroker Florida
Cooling Fans
I am new to this corvette thing and would like to know if it is normal for the fans to come on when the ignition switch is turned on evan when it is cool.
Burning Brakes
Joined: Jan 2005
Posts: 1,170
Likes: 0
From: Littleton CO
St. Jude Donor '07
Originally Posted by circlegroup
I am new to this corvette thing and would like to know if it is normal for the fans to come on when the ignition switch is turned on evan when it is cool.
If the AC is on "Auto" than the fans can come on regardless of temperature. The operations of fans is very year specific so people will need more details to give you a better answer.
Drifting
Joined: Nov 2002
Posts: 1,593
Likes: 0
From: Mobile AL
St. Jude Donor '05
If you go out, first thing in the AM, car cool, AC off, turn igniton on and the fans come on, either your fan relay is out, or the temperature sensor is out. The fans should not turn on with a cold engine, unless AC is on.
Thread Starter
Advanced
Joined: Mar 2005
Posts: 68
Likes: 0
From: Plantation 1990 L98 383 Stroker Florida
Originally Posted by SilverBeast
If you go out, first thing in the AM, car cool, AC off, turn igniton on and the fans come on, either your fan relay is out, or the temperature sensor is out. The fans should not turn on with a cold engine, unless AC is on.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
If both fans are coming on with the engine cold and the AC off, it is likely someone has rewired the fans. The main fan is switched by the ECM. It gets the engine temp from the sensor in the front of the intake manifold. The ECM uses that temp to calculate all engine engine operations. If the engine runs well, that sensor is probably OK. The axillary fan is operated by a switch in the left cylinder head between the #1 and #3 spark plugs. I'm not sure of the locations of the relays on a '90. I suspect they are mounted to the fan shroud. It is highly unlikely that both these independent systems have failed, simultaneously. I strongly suspect that your wiring has been altered. Tracing and trouble shooting non-stock wiring can be a real challenge.
RACE ON!!!
RACE ON!!!
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Don't have my manuals for the 90 handy, but here goes.
For the 90(and possibly others) if the overpressure switch on the AC circuit is bad or disconnected, both fans will fire right up. Key on engine off, regardless of engine temp. Gordon Killebrew showed me the trick of getting both fans going by simply unplugging the connector for the overpressure switch, key on and they both run. He mentioned this for people who may be in parades, don't want the AC to run, but want both fans running. I don't get invited to many parades. Not sure if the switch deactivates the compressor, no wiring diagram as I am not home.
If you own a Corvette, I would strongly recommend getting the factory service manual and the electrical supplement. New, used, ebay, whatever. With this manual, you can trouble shoot this condition.
Let us know.
dlmeyers 90 coupe zf6 3speed shocks
For the 90(and possibly others) if the overpressure switch on the AC circuit is bad or disconnected, both fans will fire right up. Key on engine off, regardless of engine temp. Gordon Killebrew showed me the trick of getting both fans going by simply unplugging the connector for the overpressure switch, key on and they both run. He mentioned this for people who may be in parades, don't want the AC to run, but want both fans running. I don't get invited to many parades. Not sure if the switch deactivates the compressor, no wiring diagram as I am not home.
If you own a Corvette, I would strongly recommend getting the factory service manual and the electrical supplement. New, used, ebay, whatever. With this manual, you can trouble shoot this condition.
Let us know.
dlmeyers 90 coupe zf6 3speed shocks
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
If both fans come on when ignition goes on, either there is a problem with the A/C pressure switch or the ECM is in limp home mode.
Locate the A/C Pressure switch in the line near the blower motor housing. It is the smaller of the two connectors.
It is a NO switch, so to test it, simply jumper across the two connector pins and turn the key on. If the fans still come on, pull the trouble codes to see why the system is in limp home mode.
The above assumes that someone has NOT wired the fan relays to bring the fans on to run constantly.