Fan's on
Thread Starter
Safety Car
Joined: Aug 2004
Posts: 4,908
Likes: 735
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
Fan's on
Hey I just noticed last night that when I start my '94 the drivers side radiator fan comes on almost immediately. What's the problem? Bad sensor? It doesn't appear to hurt anything, just sounds like a jet getting ready for take-off.....hemmm maybe she's telling me something!
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Is your AC on? If so then no prob. The AC high pressure switch kicks fan on almost instantly. If it does it with AC off and motor cold it's probably the coolant temp switch failing. If it comes on too early then it's not that big of an issue until winter when it will slow your warm up. I would still replace even so if it's coming on early without AC because if it's messing up at cold temp then I would be nervous about it messing up at hot temps...it may not, but thats just me being a newtons law believer... and I just like things to be right.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
It's could to be due to an open switch in the A/C pressure line. To check this out pull the connector, short the two pins and start the engine. If the fan doesn't come on right away, replace the sensor.
The other possibility is a short in the ECM's coolant temp sensor. To test this one, pull the connector and start the engine. If the fan doesn't come on right away, replace the sensor.
Since there is a short delay, the fan relay isn't likely to be shorted.
Thread Starter
Safety Car
Joined: Aug 2004
Posts: 4,908
Likes: 735
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
Well, when I get home I'll check, but I'm pretty sure the Automatic Climate Control is on and I'm betting the AC is coming on immediately. Thanks for the help. If I find it is something else, I'll post. 
Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
I'm pretty sure both fans should be on with a/c on. Otherwise, primary should come on at 219 and the secondary at 228. If the fan is on with the key on, a/c off, relay has probably opened.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Originally Posted by SunCr
I'm pretty sure both fans should be on with a/c on. Otherwise, primary should come on at 219 and the secondary at 228. If the fan is on with the key on, a/c off, relay has probably opened.
If it turns out you suspect the relay you can bench test it rather than just running out and buying another. I wrote a tech tip on this that may be helpful providing the 94 relays are the same as 90. The relays part #'s are in the tip for reference.
Here it is..
https://www.corvetteforum.com/techti...=282&TopicID=2
Race Director
Joined: Mar 1999
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From: I live in my own little world
NC Events Coordinator
Originally Posted by SunCr
I'm pretty sure both fans should be on with a/c on. Otherwise, primary should come on at 219 and the secondary at 228. If the fan is on with the key on, a/c off, relay has probably opened.
Yup..BOTH fans should be on with A/C!
Thread Starter
Safety Car
Joined: Aug 2004
Posts: 4,908
Likes: 735
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
I just got home to try it and the first thing I did was shut off the Climate Control. Then started her up, No fan running! Now I wonder if they both should have been running? Alchemist seems to think so. maybe I still have a problem!?
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Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
A quick check to see if it's relay or a bad fan would be to note which fan is running and swap relays and see if the other fan is now running. If so then it's probably a bad relay. If the same fan still runs then you may have a bad fan or more probable a blown fusible link powering the relay harness to that fan no matter which relay is in. To check this check for constant 12v at wire going to terminal "E" with a test light. Look inside relay to identify terminals as the diagram on top of the old ones was misleading. Let us know what you get.
Thread Starter
Safety Car
Joined: Aug 2004
Posts: 4,908
Likes: 735
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
Ok, I've had time to check things out. My bad, they both run when I turn on the Climate Control. I had to really look though, the passenger side is really hard to see and I guess I saw the fan bracket or something and thought it was the blade not moving. But getting a light down there I could see the fan running.
Thanks to all who helped out on this. I didn't mean to cry wolf.
Thanks to all who helped out on this. I didn't mean to cry wolf.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Thats good! It's much better to be in tune with your car and think you have a problem and cry wolf than be oblivious and not even notice when you do have a problem. At least you're paying attention. 
Glad it's all good.
Glad it's all good.