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Discussion Starter · #1 ·
I tried searching but all I got was the "loud fans when the A/C is on" topic
this is my first post so I just copied the "Fix My Cruze" Thread outline
1. 2012, LT, Automatic Trans.
2. 80,000 Miles
3. No Check Engine Lights on the dash
4. Radiator fans
5. The radiator fans will not shut off at all. My fiance shut off the car and went shopping and she noticed the fan stayed on even after the car was off. She expected them to shut off after a few minutes so she went into the store anyways. When she came out the fans were still on. She took it to the Chevy dealer to see if it was under warranty or a recall but they said it will be $150 just to look at it. We decided to not pay that ridiculous amount and left. She just drove home and parked the car and when I got home an hour later the fans were still on. No check engine lights at all. I unplugged the battery for a few minutes to see if it could reset something but that didn't work. I just unplugged the fans and now we are trying to figure out why this is happening.
6. United States
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Has anyone had this issue?
 

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I'd go with the stuck fan relay, but check the coolant level as well.
 

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Sounds like stuck fan relay. Watch those temps and A/C usage with the fan unplugged! Compressor needs air going over it to not build too much pressure!


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Possible that the sensor the negative battery cable goes thru is faulty. Not sure what the name of it is but its a loop that is down in front of battery tray.
I know that if you hook up any electrical accessories and you dont route your negative thru there the fans will remain on high speed.
Do the fans run with key on engine off, as if you were about to start the engine?
 

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Since the fan is still running with the car shut down, I lean toward a bad relay as well. Normally a bad sensor will set a code and the fan will jump to high as a precaution, but the car is well aware that it's not really overheating.

The relays are located in the fusebox under the hood. The guide on the underside of the lid should help you. I think there's like 3-5 relays for the fan's 3 speeds.
 
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And IIRC, the relays are all the same part number, so switching them around might identify which one is stuck, if that's the problem.
 

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As you an see that radiator fan motor is always hot, so a fused contact relay is most likely the problem. These relays are in sockets in the underhood fuse and relay box, and can be pulled straight out to learn if this kills the fan.

Can also be tested with an ohmmeter for shorted contacts.

Here is the fan circuit.

 

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Actually only one fan that uses a field winding with two taps on it, highest speed uses the weakest field winding so the armature has to speed up to produce more BEMF.

Relays and fuses are identified on the bottom of the fuse/relay cover, have to press those tabs together to remove it. my money is on the high or medium speed relay. low speed goes through that way overworked ignition relay. Already replaced my ignition relay with a good one.
 

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The power for all the relay coils go though the Ignition Relay. So unless the ignition relay was still on for some reason, I'd think it would have to be the high speed relay.

Now, the question is why is that one stuck? It's rare for a Cruze fan to go high speed in the first place. I'll bet there's another problem causing the car to keep going to high speed until the relay contacts stuck. Possibly a bad fan motor that took out the thermal fuse in the resistor pack.
 

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An ideal motor has zero resistance in the armature and stator windings, the only thing that resistance does is to decrease the efficiency of the motor. So startup current is high until the armature builds up speed to produce a counter EMF, called generator action in the motor. If due to poor bearings or a dreaded shorted turn in any of the windings, the current can skyrocket. So the switching device takes a beating.

Ha, what ignition switch? Another tiny switch that fires commands to the BCM and the PCM. Driver transistors are used in the BCM and PCM that can short out for a various number of reasons.

Ha, already replaced shorted or defective transistors, in BCM, EUC's, and even in ABS modules, heck of a lot cheaper than spending as much as 1300 bucks for a new one, just because a three cent transistor is toast. But this was with through the hole PCB boards, a heck of a lot more difficult with surface mount.

Ha for years, UL, CSA, military, and European always required a good mechanical connection for all electronic components before soldering, but now everything is just tacked on with a tiny bit of solder. By the way, automotive was always immune to these standards, could do anything they wanted to.
 

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Discussion Starter · #12 ·
So it ended up just being coolant was low. At least that's what I think it was. I checked the coolant levels and it was at the bottom line of the reservoir tank. I added coolant and fired it back up. Fans stayed off until the engine warmed up a little and I turned on the A/C. Even with the A/C on the fans just kicked in for a few seconds and back off for a while and stayed doing that. Sounds like that was the issue. Thanks for all the input guys!!


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How fast was the fan running? The car has 3 speeds. Low/medium isn't all that loud. If it's hitting a volume audible from a few cars away, you've still got a problem.
 

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So it ended up just being coolant was low. At least that's what I think it was. I checked the coolant levels and it was at the bottom line of the reservoir tank. I added coolant and fired it back up. Fans stayed off until the engine warmed up a little and I turned on the A/C. Even with the A/C on the fans just kicked in for a few seconds and back off for a while and stayed doing that. Sounds like that was the issue. Thanks for all the input guys!!


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Really sounds weird to me if you tape the hood switch closed so the vehicle thinks the hood is closed, lock the doors, and with an inductive ammeter on the negative battery cable, the BCM is suppose to go to sleep in under five minutes. Got the impression your fan was on 24/7. And just because the recovery tank was low, shouldn't have an overheating condition.

More likely either the high or medium relay contacts were closed. I studied these relays, super weak return spring in these, not even a real spring, a piece of beryllium copper.

Feel one of your relay contacts was closed without being energized and maybe a bump or two worked it free. Let's see if this happens again. Or maybe your BCM is not going to sleep.
 

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Discussion Starter · #15 ·
Ok I actually figured out the real problem. Like most of you have said it was the relay. I thought it was the coolant because once I topped it of the fans suddenly turned off. It must have be good timing. But the fan problem just started happening again and I checked the coolant level. It was right where it should be. I opened the fuse box and just gave the relay a flick and the fans just shut off. Happened more than once. Already ordered a new relay and should be here tomorrow. Glad it was only a $4 fix. Thanks guys!


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Ok I actually figured out the real problem. Like most of you have said it was the relay. I thought it was the coolant because once I topped it of the fans suddenly turned off. It must have be good timing. But the fan problem just started happening again and I checked the coolant level. It was right where it should be. I opened the fuse box and just gave the relay a flick and the fans just shut off. Happened more than once. Already ordered a new relay and should be here tomorrow. Glad it was only a $4 fix. Thanks guys!


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Thanks for the feedback.
 

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I tried searching but all I got was the "loud fans when the A/C is on" topic
this is my first post so I just copied the "Fix My Cruze" Thread outline
1. 2012, LT, Automatic Trans.
2. 80,000 Miles
3. No Check Engine Lights on the dash
4. Radiator fans
5. The radiator fans will not shut off at all. My fiance shut off the car and went shopping and she noticed the fan stayed on even after the car was off. She expected them to shut off after a few minutes so she went into the store anyways. When she came out the fans were still on. She took it to the Chevy dealer to see if it was under warranty or a recall but they said it will be $150 just to look at it. We decided to not pay that ridiculous amount and left. She just drove home and parked the car and when I got home an hour later the fans were still on. No check engine lights at all. I unplugged the battery for a few minutes to see if it could reset something but that didn't work. I just unplugged the fans and now we are trying to figure out why this is happening.
6. United States
7. LHD

Has anyone had this issue?
My son and I bought a 2011 1.8L Cruze. It developed the same fan issue. It was stuck in turbo mode whenever the engine was running. The problem was the temperature cooling sensor on the thermostat housing. For good measure I also replaced the thermostat but it wasn't necessary.
 

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I tried searching but all I got was the "loud fans when the A/C is on" topic
this is my first post so I just copied the "Fix My Cruze" Thread outline
1. 2012, LT, Automatic Trans.
2. 80,000 Miles
3. No Check Engine Lights on the dash
4. Radiator fans
5. The radiator fans will not shut off at all. My fiance shut off the car and went shopping and she noticed the fan stayed on even after the car was off. She expected them to shut off after a few minutes so she went into the store anyways. When she came out the fans were still on. She took it to the Chevy dealer to see if it was under warranty or a recall but they said it will be $150 just to look at it. We decided to not pay that ridiculous amount and left. She just drove home and parked the car and when I got home an hour later the fans were still on. No check engine lights at all. I unplugged the battery for a few minutes to see if it could reset something but that didn't work. I just unplugged the fans and now we are trying to figure out why this is happening.
6. United States
7. LHD

Has anyone had this issue?
My son and I bought a 2011 1.8L Cruze for his first car. What a money pit it's been. It developed the "turbo fan" issue amoung other things not long after buying the car. The problem was the temperature cooling sensor on the thermostat housing. I also changed the thermostat for good measure because it had never been changed out.
 
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