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Discussion Starter #1
I did a tune-up, valve cover gasket, crank positioning senor, starter and oil change. Car started right up, sounded the best it ever has... Until it started to warm up, started getting hot and I noticed it overheating.
Noticed my fans weren't turning on. I removed the thermostat and the rubber was torn up, replaced it. Still no fans, I'm at a loss... Any ideas? I feel I'm so close to finally getting my car to actually work....
 

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Turn on the ac and see if the fan comes on. If not then check the relays - ac and radiator. If it looks good, check the fan motors itself by disconnecting it and directly connecting a 12 volts to it. Also check the connectors for power.
 

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Fuse or relay? Pull the relay and jumper the #30 and #87 contacts and see if the fan starts then. Use a stout wire as it's a high amp current.

If it starts then the fan, fuse and wiring from the relay are good and then swap a different relay in to see if the original is bad.
 

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Discussion Starter #4
thank you. I did check fuses, did the wire fan thing and they worked, fans do not turn on when a/c was turned on. I also checked power to the relays and their is power going to them both, but at the harness near the battery where I think they connect, theirs no power. I'm new to this and as far as troubleshooting I don't know where to start. This may sound like a real dumb question, but the fuses under the hood (the fat ones) how can you tell their bad?
 

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You can get a multi meter, set it on ohms and place the leads across the two pins on the fuse. If good it will read a real low number, if bad it will get no reading.

Jumpering at the relay would show that the fuse is good if the fan came on. I would swap the relay with another.
 

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This is a really basic circuit, and you have tested the expensive bits. A temperature sensor turns on the primary fan, and the AC turns on the secondary fan.

" I also checked power to the relays and their is power going to them both,"

Don't be fooled. You will have power on the CONTACT side of the relay if the fuse for the fan is good. But what you need to confirm is that the COIL gets power when the temperature rises. I don't have electricals on your model, but I will see if I can track them down and give you more specific points to check.

Found this:

 

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The relay is turned on by the ECU grounding it. With the key on, relay out, there should two terminals with 12v+, #87 with nothing and another (guessing the right side looking at it from the side of the car) that should ground when the ECU commands it.

So for the hi speed fan with the AC on engine running the ECU should show a good ground from that terminal to the engine block. Same with the low speed fan at 203F or so as the ECU would turn that on.

If you do not get these relay coil turn on ground signals there is an issue with the wiring to the ECU or the ECU.
 

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This would be easy with a good wiring diagram. The video I posted shows a temp sensor in front of the radiator. Now, that could run the fan relay directly, or it (more likely) sends a signal to the ECU which then sends a signal to the relay.
 

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Um, were the cooling fans working before you did all the work? If so, you wouldn't be the first of us to miss a connection that was unplugged to gain clearance for access to what you are working on.
 

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You can usually get the ECU to turn on the fans when the engine is running with the temp sensor disconnected.
 

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Discussion Starter #12
You brought up a good point flemmons, and yes they were working. In the back of my mind that I was thinking that. Off I go under the hood... Thank you all for the advise.
 

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Ah, c'mon sparky! They are just using different relays for different speeds. No different from a house fan, but the ECU (BCM) just enables different relays based on A/C use and engine temp. :)

At one time, GM used a pressure sensor to turn on the fan during A/C use. Awful design because they monitored the Freon high side from the compressor. High pressure, turn on the fan. Problem was at low idle speed with the A/C on the pressure line didn't have steady pressure, but pulsed. Which caused the pressure sensor to toggle. Which toggled the relay. Which switched the fan off and on very rapidly. The fan usually survived, but the relay contacts would arc themselves closed and the fan stayed on. And since no one thought this through, the power through the relay contacts to run the fan came straight off the battery through a fuse. So, you went to the grocery and came back out to a very slow running fan and a near-dead battery. Really stupid design. But savvy owners knew where that relay was and listened as they walked away!

:laugh:
 

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Six relays, a fan control module (video), an engine PCM and the AC ECU.
Yeah, it sounds like a house fan :wink:
 

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Discussion Starter #20
Flemmons your the man. There was a connection on the back of the manifold that wasn't completely plugged in, I must of knocked it loose putting on the manifold. Rookie mistake.. Thank you everybody for the help!
 
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