Both radiator cooling fans won't turn on vehicle overheats

My information shows that the 2001 tahoe uses a fan clutch and does not any electric fan. There could be exceptions, but if this is an add on aftermarket fan, there would be some type switch with a relay or fuse wired in the system. First make sure that the radiator is not partly restricted. Using a inferred thermometer check to see is all the radiator tubes are the same temp. Most of the time, the lower tubes are cooler because they are restricted. Also make sure the fan clutch is good. After driving it and the engine is at running, shut the engine off and watch how many times the fan rotated. It should stop after several revolutions.

Hi Naomi , there is a lot involved in the control of the cooling fans on your vehicle ! There are three fuse's , three relays an a fan control unit !
1. radiator fan main relay , located in underhood relay box A
2.condenser fan relay , located in underhood relay box A
3.radiator fan relay , located in underhood relay box C
4.Cooling fan fuse # 47 20amp. underhood fuse / relay box
5.condenser fan fuse # 50 20amp in underhood fuse / relay box.
Any one of these could cause them to not work, rather then just replacing parts an wasting money you should take it to the repair shop !

there are 2 or 3 fans up front on all A/C equipped cars.
the fan closed to engine (rad rear) turns on parked and idling
all engines will overheat parked, if the fan goes dead.
so are you saying this fan is dead.?
if it dont overheat moving fast then the cooling system is usually good
and then you stop at a traffic light this fan must turn on.
on cars with 3 fans , some stage up, 2 on if too hot. or all 3 on.
the FSM covers this logic clearly.
in the USA car.
the element has 2 fans (some engine options my differ)
the right fan is for A/C
and left fan is for engine cooling, (im looking at alldata.com to see that)

the fan turns on via a relay that he PCM controls
the PCM see the ECT sensor in the engine go to over say 225F and
it closes the relay, and the fan spins at full speed.

fuse 4 runs this relay, in the fuse box
the relay and fuse are named
radiator fan.

If the fan not turning on when car engine getting hot,then car will notice overheating.Click this link below for troubleshooting:---http://technoanswers.blogspot.in/2012/02/car-running-hot.html--------To know how engine cooling system works ,click the link below :----Engine cooling components working?

http://repairhelpcenter.blogspot.com/2011/11/engine-cooling-components-working.html

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How does Vehicles Engine cooling system works? http://repairhelpcenter.blogspot.com/2011/11/how-does-vehicles-engine-cooling-system.html
------------How to Replace Engine cooling Fan:-- http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-engine-cooling-fan-on.html
-----------Replace Fan Relay but still Radiator cooling fans not working? http://schematicsdiagram.blogspot.com/2011/12/replace-fan-relay-but-still-radiator.html
----------DIC says "COOLING FAN FAULT"? http://schematicsdiagram.blogspot.com/2011/12/dic-says-cooling-fan-fault.html
---------Where Is Radiator Fan relay and Fuse Located?

http://schematicsdiagram.blogspot.com/2011/12/where-is-radiator-fan-relay-and-fuse.html

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This will help.

Thanks.

A bad relay will not blow a fuse. The radiator cooling fan must run with the A/C on or the vehicle will overheat and the A/C will perform poorly. First I would check the draw on you cooling fan motor-it may be blowing the fuse, or you have a wire shorted to ground.

You may have an engine cooling fan that isn't working. When you run the heater you are removing some heat from the cooling system which aids in keeping the engine cool. If the cooling fan in front of the radiator isn't working then the engine can overheat at slower speeds when there isn't any air being forced through the radiator by the forward motion of the vehicle. If this problem is happening only at slow speeds then I would suspect a cooling fan BUT if it happens at steady speeds over 35 mph you may have a different problem.Hope this helps and good luck!

Hello and welcome to FixYa! If you have overheating problem, it can lead to multipleissues. You may be running on low coolant that's why the vehicle overheats. Ifthat's the case, please add coolant and make sure that it sits on the rightlevel, too much coolant can cause overheating too for coolant will overflow. The vehicle may have a faulty or worn out radiator blowermotor that's why it overheats. If that's the case then you will need a blowermotor replacement to resolve the issue. If the radiator is clogged with dirt and rusts this issueoccurs too. The coolant doesn't flow normally on the cooling system if it'sclogged. If that's the case, I strongly suggest that you have the radiatorflushed to drain out dirt and rusts. If you think that the radiator served youenough then it's better to have it replaced. Please do check the radiator hoses, If you have worn outhoses it can cause coolant leakage which can result to overheating. A tiny holeis good enough for the vehicle to overheat. A faulty thermostat sensor can cause the issue too. If youhave worn out thermostat, the fan may not trigger that's why the fan won't workwhen under stressed conditions. A blown radiator blower fuse can cause thisissue too so I suggest that you check the radiator blower fuse and replace itwhen necessary. What causes the radiator blower fan fuse to blow? It's becauseof a failing radiator blower motor, If that's the case have the radiator blowerfan motor replaced. If the fluid in radiator doesn't circulate then it meansthat you have a blown head gasket or a faulty water pump. I suggest that you gofor the water pump replacement first specially if you think that it's near theend of it's service life. Usually, water pops out the radiator when engine isreved (a sign of faulty water pump and possible blown head gasket). Hope you find this information helpful enough and thank youfor using FixYa! Have a good one!

Check the operation of the radiator cooling fan circuit:-
1) check fan control temperature sensor is ok,
2) check/replace the cooling fan control relay,
3) check supply fuse for cooling fan is ok.

When ever the car overheats,it is always the best thing on your car,to check the cooling fans.When the ac is on,look to see if the cooling fans are running,and running fast,and smoothly.In your case,I am going to go out on a limb,and say they are not.First check for blown cooling fan fuse.Then,if the fuses are alright,check the cooling fan relays,most likely more than one.One prong,or spade coming out of the relay,is ground(where it plugs up).To make the relay energize,ground this terminal with a test light .Just like you are using the test light to check for 12 volts.When you touch the ground spade on the relay it will energize the relay to turn the fans on.Just pull the relay out of it`s spot,just enough to touch the spade.Do this with the ac on,and engine running.The clutch relay on most cars will energize the relay,but the ac compressor is working on your car,so it is either the fan relay,or the high side switch on the ac system that is bad.Try and see if the cooling fans,both of them,or one of them,will come on by them selves as the car warms up,with the ac off.The fan or fans should come on,and go off by themselves.Don`t let the engine overheat,keep a good eye out not to let that happen.If the fans never come on,then,the fan,or fans could be bad.You can test them by running wire from battery to the fan,and grounding to frame.Now the fuse,or relay being bad will also cause this.If a fuse is blown,then ,one or more of the fans are bad,and will have to be replaced.The fans cool the radiator for the engine and transmission cooling,and the condenser for the ac system.If the condenser is not cooled down,the ac freon will be to warm to cool the vehicle.If I can help,let me know.>>[email protected]