# Radiator fan comes on when I start car and does not go off



## Fuhnominon (Mar 19, 2015)

Hey I'm from beautiful Barbados; the land of the flying fish! I just bought 2012 chevy Cruze 1lt and it was fine for first 4 drives but now as soon as I turn that ignition, after literally 2 seconds the radiator fan comes on and stays on. It's extremely loud and goes full blast. Any ideas on what is causing this to happen and any suggestions on how to fix it? Your help is super appreciated.
Fuhnominon (pronounced phenomenon)


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## obermd (Mar 3, 2012)

Welcome to CruzeTalk. Check your engine coolant level. When cold it's supposed to be at the level of the top rib in the surge tank.


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## ChevyGuy (Dec 13, 2014)

What happens if you start the car with the A/C turned off? Any better?

The Cruze has a 3-speed fan. In normal operation, it will never go to full speed "jet engine" level. That's a sign that something is screwy with one of the sensors - but there are several that can do that.


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## NickD (Dec 10, 2011)

This could be the problem.










Radiator fan controller shorted out. All started with FWD, where prior art was an engine driven fan.

But even with engine driven fans, fan load was considered a problem. So came out with this thing.










Fluid fan clutch, have an energy crisis so the first thing our congress picks on is the pilot light, making any natural gas device extra expensive with a lot more problems and don't even work if your electricity goes out. Was the same with the fans decreasing fuel economy.

First off the fan only draws an absolute maximum HP of one third, so playing with nothing to start with. In city traffic, need all the cooling you can get. But at highway driving, have a wind milling effect where the fan load is practically nothing. If that fan clutch went bad, would not get any engine cooling period, ha, got rid of these darn things in hurry. This deal with thinking. Didn't make a darn bit of difference in fuel economy, more lies.

Other false advertising was done by VW with an air cooled engine. Still had a fan belt driven by the generator with an extra shaft on it. With generator problems using quickly worn out brushes, had to remove the entire engine to replace it. 

Real age old problem is sticking that bug collector in front of the engine called a radiator, further complicated by putting a condenser in front of it. Fan is worthless if it can't pull air through these vital heat exchanger appliances.

With FWD, elected to go electric, more problems, a 60 amp alternator wasn't powerful enough, had to be increased to 100 amperes to drive these fans. And they would have to work the hardest in city traffic with low engine speeds where the output of the alternator is at its lowest point. Really a huge problem in V-6 and 8 engines, least two fans were required.

Bean counters did not like a radiator thermostat to control the fans. Just use the engine temperature sensor, more problems, before the fans came on, cooling system was ready to blow its cork. Worse problem was thermal cycling, engine would cycle constantly between 195 to 235*F, really compounded by sticking an aluminum head on a cast iron block. So if you are wondering why you are having problems, these are the reasons. But as long as it gets through the BB warranty period, who cares. Consumer pays for this. 

I got around this by adding a thermistor to my radiator, talk about making mods, would kick on the fans if the center of the radiator hit 160*F, this would cure the thermal cycling problem, but it was a major job. 

Then the radiator cap had to go, safety reasons were given even though there is a warning sign on it. But new problems are created, first off the cheap recovery tank is seeing a full 20 psi of pressure, second if that signal hose is blocked or has a kink in it, your reservoir would show full while your radiator could be empty.

One thing I like about my Cruze, has a tiny four cylinder engine in it and its cooling requirements are minimal, getting old and tired, never want a FWD V-6 or V-8 again. One thing I hate about it, can no longer remove the top radiator shroud to get at the radiator and condenser to clean off the bugs. Have to do this from underneath. With bugs blocking air flow, high side of the AC system gets super high with pressures that causes wear and tear on the compressor, plus reduces cooling. Followed by engine cooling problems. 

Another thing they could do is to use tungsten contacts in the relays. They can take the heat, silver dusted brass doesn't last very long and will weld together. Now all the relays are soldered to a PCB to save even more money, but some can be replaced.

So don't wonder why you have problems.


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## ChevyGuy (Dec 13, 2014)

NickD said:


> Radiator fan controller shorted out.


Nothing like that in my Cruze. BCM does the controlling. Perhaps a stuck relay, but more likely either a problem or a sensor is lying.


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## NickD (Dec 10, 2011)

ChevyGuy said:


> Nothing like that in my Cruze. BCM does the controlling. Perhaps a stuck relay, but more likely either a problem or a sensor is lying.


Yeah, must be smoking crack when I posted that picture, probably a Cruze sold in Timbuktu. US vehicles are controlled by the BCM with relays, K1 and K2 mounted in the underhood fuse/relay box. But this guy is located in the Caribbean, so who knows what they are doing there.

Have to remember, this is an international board.


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## jblackburn (Apr 14, 2012)

Agree with a coolant temp or MAF sensor as the most likely cause, but check the coolant level to make sure there is still coolant in there. 

What engine is this - 1.8L or 1.4T? 

The 1.8s also have issues with the computer-controlled thermostat that can make them go into screamy mode. The 1.4s have leaky water pumps that can make the temp sensors disagree with each other, and the fan screams as a fail-safe.


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## brian v (Dec 25, 2011)

The thermostat will give a cel . yeah more probable the thermostat .. well any who hope OP can get a resolution from GM for cheap . like the extended warranty placed upon these more than likely failures to the more than likely parts that clutter the econobox crowd 

Hay let us ask Tomko ? 
Heisenbeg compensator Hah .. Nahh !


Oh wait a minute here if I lived in the carribean . I would not care if the fan screamed upon start up !


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## NickD (Dec 10, 2011)

Definitionof the Caribbean is of or relating to the Caribbean Sea, its islands, or its Central or South American coasts or to the peoples or cultures of this region. Or Latin American countries. Ha, in my first trip down to Venezuela, a Latin American country with a 2002 Toyota Corolla with engine running problems, figured it was OBD II, so tossed in my scanner. Sure looked like any other Toyota, but with no diagnostic socket. Opened the hood to find a carburetor. Brought the wrong tools. 

Cruze thermostat is no different than any other wax thermostat, fooled me at first, thought it was electronically controlled, it ain't, just has an added nichrome heater element in it to fool it into it thinking its running hotter when you hit the gas to kick in the turbo. Can sure question the time delay on this, but one thing for sure, a lot more expensive than a conventional thermostat. 

Really don't know what we are dealing with this subject vehicle. Some vehicles kick on the fan if the AC is left on on startup, others look at other engine parameters to save a gram of fuel. OP said this just started, is this because the AC switch was left on?

Ha, wife to be always left her AC switch on, mold build up was so bad, evaporator had to be replaced for $$$$$ down there, nobody told her that.

US equivalent for gas down there was only 9 cents per gallon, but a pint of drinking water cost two bucks. Something we have in common, get you one way or the other.


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## Fuhnominon (Mar 19, 2015)

Thank you for the tip on coolant level. When the fan first started coming on and staying on the coolant was low. But then I topped it up with correct coolant and it still comes on as soon as car is started. And it's super loud! The temp gauge doesn't even get half way so it's not a case of engine overheating, I don't think. Also, the battery was disconnected and reconnected a good few times (positive connection) before this started. It was at body workshop and then it just started. Any suggestions?


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## Fuhnominon (Mar 19, 2015)

Chevy guy, thanks for info. I never start it with a/c on. It is blowing at full speed so maybe as you say it's a sensor. Will I need to do a diagnostic test to pin point which sensor is bad? I was doing some research and I was looking to replace the coolant temp sensor first and see if that solves the problem. What do you think?


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## Fuhnominon (Mar 19, 2015)

NickD said:


> Yeah, must be smoking crack when I posted that picture, probably a Cruze sold in Timbuktu. US vehicles are controlled by the BCM with relays, K1 and K2 mounted in the underhood fuse/relay box. But this guy is located in the Caribbean, so who knows what they are doing there.
> 
> Have to remember, this is an international board.


Yes i I live in Caribbean but this model chevy I actually imported from USA i's left hand drive and was made in USA. However, it was in an accident (side lash) and the mileage is high, at 48,000 miles already. Would the high mileage contribute to this problem?


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## Fuhnominon (Mar 19, 2015)

jblackburn said:


> Agree with a coolant temp or MAF sensor as the most likely cause, but check the coolant level to make sure there is still coolant in there.
> 
> What engine is this - 1.8L or 1.4T?
> 
> The 1.8s also have issues with the computer-controlled thermostat that can make them go into screamy mode. The 1.4s have leaky water pumps that can make the temp sensors disagree with each other, and the fan screams as a fail-safe.


This is is a 1.4 1LT. What's an MAF sensor? Apart from the great annoyance the noise from the fan going at top speed all the time while driving or at a stop, what issues will the fan spinning all the time create?


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## obermd (Mar 3, 2012)

Fuhnominon said:


> Yes i I live in Caribbean but this model chevy I actually imported from USA i's left hand drive and was made in USA. However, it was in an accident (side lash) and the mileage is high, at 48,000 miles already. Would the high mileage contribute to this problem?


Given this information definitely take a look at your coolant level. The 1.4T engine (LT, ECO, LTZ) is notorious for coolant loss. The 1.8 engine (LS) has had thermostat failures. As long as it's not a broken hose coolant loss is usually covered under the power train warranty.


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## Fuhnominon (Mar 19, 2015)

brian v said:


> The thermostat will give a cel . yeah more probable the thermostat .. well any who hope OP can get a resolution from GM for cheap . like the extended warranty placed upon these more than likely failures to the more than likely parts that clutter the econobox crowd
> 
> Hay let us ask Tomko ?
> Heisenbeg compensator Hah .. Nahh !
> ...


My my main problem with radiator fan is: it comes on and does not go off, could this damage engine or cause other problems? Plus the noise it makes is tremendous when I'm driving thru neighborhood at night this thing sounds like a fighter jet going thru the neighborhood.


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## obermd (Mar 3, 2012)

If the radiator fan is coming on and staying on it's because either the thermostat is stuck open or there is no coolant in the system. In the former case - failed thermostat - you may or may not be damaging the engine. In the latter case - low coolant - you are definitely damaging the engine. Open your hood and take a look at the surge tank just in front of the drivers seat. If the coolant level is below the top of the large lower hose you need to immediately refill with the 50/50 dexcool/water blend. If it's above the hose I would suspect the thermostat. You may or may not get a CEL in either case.


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## jblackburn (Apr 14, 2012)

Fuhnominon said:


> This is is a 1.4 1LT. What's an MAF sensor? Apart from the great annoyance the noise from the fan going at top speed all the time while driving or at a stop, what issues will the fan spinning all the time create?


Mass airflow. It is the sensor on the tube leaving the air filter box - if the plug is slightly askew, it can make the fan scream (although I think it would throw a code). When I unplugged mine once to remove the air box, the fan screamed afterward until I snugged the connector back up.


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## brian v (Dec 25, 2011)

His thermostat is Bad . Plane and simple ... or plane and simple MAF sensor took a hike and left for some cooler air ..


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## Blue Angel (Feb 18, 2011)

Fuhn, do you get any error messages? Do all of your dash gauges work correctly? I think they do based on your posts, I just want to be sure.

I get an issue sometimes where my car will run the fan at full speed, but this is because I use a block heater which preheats the engine. The start up diagnostics don't like my block heater since the coolant temperature sensor is reading a different value than the intake air temperature sensor. In this case I get an error message to the effect of "Engine Overtemp, A/C Off" or something like that. The car drives fine but the coolant temperature gauge stays at zero and the fan runs constantly.

Just to be clear, my car is operating properly, it's just not programmed to work well with a block heater.

I doubt this is your problem, but I thought I'd just throw it out there.


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## NickD (Dec 10, 2011)

Come on, the fan doesn't even come on until an overheat condition is sensed, either K1 or K2 relay contacts are welded together. Says as soon as he switches on the engine, assuming its cold, the fan comes on.

Had this underhood fuse relay box all apart when I installed my fog lamps. Didn't have too, but wanted to study it. No longer using real relays sockets with relays with cap on them so one could clean the contacts. Made in China molded relays that can't be opened without wrecking them and mounted on a PCB, two boards stacked and never have seen so many interboard connections in my life.

Was going to cross reference the relays, but what the heck, will wait until I have a problem. But replacing the entire stack is not too bad.











[ 1 ] ELECTRICAL / ELECTRICAL / FUSE & RELAY / Fuse & relay box 
  *Part Number: 95216200 

fuse & relay box auto trans *
PARTS: Order by description. 




[ 1 ] ELECTRICAL / ELECTRICAL / FUSE & RELAY / Fuse & relay box   *Part Number: 96982033 

fuse & relay box manual trans *
PARTS: Order by description. 



But is this the culprit or the victim of a defective radiator fan?











Now talking about more bucks.


[ 2 ] COOLING SYSTEM / COOLING / COOLING FAN / Fan & motor   *Part Number: 13427160 

fan & motor 1.4 LITER TURBO, manual trans *
MSRP*Online Price*$201.15*$129.14*  
 
 
 
   [ 2 ] COOLING SYSTEM / COOLING / COOLING FAN / Fan & motor   *Part Number: 13427161 

fan & motor 1.4 LITER TURBO, auto trans *
MSRP*Online Price*$296.80*$158.84* 
MSRP*Online Price*$211.21*$128.82



* 
MSRP*Online Price*$231.63*$141.27* 


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## NickD (Dec 10, 2011)

That sure didn't work out right and can't edit, here are the prices for that relay/fuse board stack.


[ 1 ] ELECTRICAL / ELECTRICAL / FUSE & RELAY / Fuse & relay box   *Part Number: 95216200 

fuse & relay box auto trans *
PARTS: Order by description. MSRP*Online Price*$231.63*$141.27*  
 

 
 

    [ 1 ] ELECTRICAL / ELECTRICAL / FUSE & RELAY / Fuse & relay box   *Part Number: 96982033 

fuse & relay box manual trans *
PARTS: Order by description. MSRP*Online Price*$211.21*$128.82* 


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## ChevyGuy (Dec 13, 2014)

NickD said:


> Come on, the fan doesn't even come on until an overheat condition is sensed, either K1 or K2 relay contacts are welded together. Says as soon as he switches on the engine, assuming its cold, the fan comes on.


I still wouldn't rule out a unhappy BCM.

Question: what is the power source to the contacts of the relays? If a contact is welded closed, will the fan run all the time (battery) or is the power source switched? I don't have the manual handy, but I thought it was battery. If true, then that shoots down the bad contact theory.


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## jblackburn (Apr 14, 2012)

It sounds like one coolant temp sensor disagreeing with another, as Blue Angel pointed out. I don't think a handheld scan tool will show both sensor readings, but GM's scan tool probably will.

You can also test resistance on the sensors with an ohm meter, but I don't know what the resistance values for the sensors should be on these cars.

I do wonder if the coolant level got low enough to create an air bubble somewhere in the system.


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## ChevyGuy (Dec 13, 2014)

jblackburn said:


> I do wonder if the coolant level got low enough to create an air bubble somewhere in the system.


I'm not sure what a air bubble would do for stone-cold, first thing in the morning startup. Once it starts warming yeah, but I think it would take at least tens of seconds if not the better part of a minute it do it.


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## NickD (Dec 10, 2011)

Electric radiator fans are not exactly new, have over a 40 year history namely started with FWD vehicles. Neither are point contact relays with points welding together, would give these an over 100 year history.

What has changed is the ease in replacing these relays, sure making it a lot more difficult today. And not nearly as robust.

With FWD vehicles, came the strut, not that good engineers thought this was a good idea, but marketing sure loved it, a heck of a lot cheaper, more profits. Instead of using an easy to replace shock, they never last as long as separate springs. Wrapped the spring around the shock and called it a strut. And instead of using double wishbone suspension, just a single control arm, more money saved, more profits.

Is a trade off, with double wishbone, when hitting a bump, the tire always remains vertical, but not with a single control arm. Wheel is at the end or arc so camber changes drastically when hitting bump causing more tire side wear, even flat spots. Guess what kind of suspension the Cruze is using.


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## Fuhnominon (Mar 19, 2015)

Hey guys, thanks to every one for their valuable input. I'm on vacation now in Canada but as soon as I get back in a couple days I will go thru all the things you guys pointed out to get to bottom of this fan issue.
fuhnominon


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## NickD (Dec 10, 2011)

Would be nice if the shop manual would specify what the full load current is on these fan or other motors, but they don't do this. Just say replace it with a known good one. But how do you know a known good one is if they don't tell you what the full load current should be?

One shorted turn in the armature or more commonly, but using too soft of a copper in the commutators, they would be bleeded together causing a short circuit. Motor will still run, but the input current would be a lot greater. This will overload the point contact relay contacts together causing the fan to run continuously. Replacing the relay would only be a short term cure, will happen again.

Armature can be tested with a growler, provided it can be removed if screws were used, but this is also history, either welded or crimped together. So you just buy a new fan motor.

Only 170 bucks for this POS.










Ha, can buy a much better fan at Walmart for 16 bucks, but need 120VAC to plug it in, even has oil fill holes in it and screws. 

Cooling fan fuses are 42 and 45, generally these are rated about 30% higher than the maximum fan current, so gives an idea the fan current should be in the 20 amp range. Can also pull K1 and K2 relays to see if this kills your fan. They are plug in types.


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## Fuhnominon (Mar 19, 2015)

Hey thank you to all you guys. I got the fan problem solved. It was actually a result of the AC compressor going bad after months and months of car just being parked and ac not being used. Apparently the compressor problem was sending message to computer and it was compensating. So fixed and upgraded the compressor and car is quieter than a mouse. Whooohoooo!! Thanks gain all you guys!!


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## cadco1 (Apr 15, 2019)

Fuhnominon said:


> Hey I'm from beautiful Barbados; the land of the flying fish! I just bought 2012 chevy Cruze 1lt and it was fine for first 4 drives but now as soon as I turn that ignition, after literally 2 seconds the radiator fan comes on and stays on. It's extremely loud and goes full blast. Any ideas on what is causing this to happen and any suggestions on how to fix it? Your help is super appreciated.
> Fuhnominon (pronounced phenomenon)


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. It's a $30 to $35 quick fix. Look for the video on YouTube. I also changed the thermostat for good measure because it had never been changed out.


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