Question about Cars & Trucks

1 Answer

Radiator Cooling Fans are not running. Where are the sensors?

Posted by on

Ad

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Top Expert:

    An expert who has finished #1 on the weekly Top 10 Fixya Experts Leaderboard.

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

  • Cars & Trucks Master
  • 2,044 Answers

As it gets cooler, the fans will not turn on until it gets to Operating Temperature. The Sensor is normally near the Thermostat Housing. If they are not running and is overheating, then there are Fan Relay's in the Engine Compartment but if it is Cold then they will not come on until it gets to 205 degrees

Posted on Nov 07, 2014

Ad

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Ad
FRANKSFIXIT
  • 72 Answers

SOURCE: Radiator Fans 1999 plymouth grand voyger

My answer:

I answered a similar ? at Yahoo Answers awhile back, and it solved that person's problem on their 1987 Jeep.

Though you weren't very specific as to your 2003 Jeep Grand Cherokee's problem by just saying the fan motor doesn't work, I'm taking it that we are talking about the "radiator fan motor" here.

You most likely have a two-fold problem going on with your radiator cooling fan.

Seeings a new fan motor didn't solve the original non-op problem we can definitely establish that the old fan being bad really wasn't bad at all and NOT the problem to start with.

As with any 12-volt DC automotive motor (whether for the radiator cooling fan, windshield wiper motor, interior passenger compartment cooling/circ fan, etc) a simple disconnected from the car's electrical system test should have been done 1st to make sure the old fan motor was really bad. Too late for that now though. I myself would have seriously doubted that a 6 year old fan motor would have been bad already.

If you had no recent engine or radiator related mechanical work done to the Jeep - as of late - then the problem may not even be a bad wiring harness connection, but you never know.

If all the radiator fan Temp related Sensors & Thermal Switch connectors are properly seated then we need to look at yet another possibility having eliminating a wiring connector type problem.

On most radiators with an electric assist fan(s) there is also an electric Thermo Sense switch (TS) mounted on the radiator itself that has to be working properly otherwise this fan switch could stick in the CLOSED position (set point usually 190 degrees F) leaving the fan to run all the time while the engine is running. Make sure it is connected as to the wiring connector, as I've seen this connection get pulled apart from other engine related work being done or else from a bad connector itself.

If this TS goes bad and someone disconnects it so as to stop the fan from running all the time - then it may look like the fan itself is bad when it really isn't.

On the other hand this TS switch could actually stick in the OPEN position (though this is very rare with this type of Thermal switch), and then the fan wouldn't run at all, and the engine would probably run HOTTER then normal as a dead giveaway. If your engine is running HOTTER then normal I would go directly to this TS and check it for proper operation. It's usually mounted on the radiator fan bracket nearest the radiator with a separate 2-wire wiring connector.

If it's working properly - when the ignition is turned off - the fan should still turn off as it is usually controlled by a timed RELAY circuit as a failsafe. Does it??

Hopefully you don't have any engine cooling problems to start with, but if you do follow the guidelines below:

If the engine thermostat is sticking CLOSED, or indeed stuck CLOSED, that could also cause the fan to run excessively. Running plain water in the engine and not proper 50/50 antifreeze/coolant mix can also cause the engine to run much hotter then normal and thus adds to running the radiator fan more frequently then normal.

Excessive radiator fan running leads to just one thing, and that is worn out bearings. Some of these fans aren't made that good to begin with!

If the fan is indeed 'tired' or has a tendency to try and freeze up there should be safeguards to prevent wiring from burning up.

Most radiators have 2 thermo-switches (TS), one being an ambient radiator surface mounted TS, and the other one being an internal (screwed into) radiator mounted TS. There might even be a 3rd fan TS that is clipped directly to the fan motor case itself to sense an over-temp situation like that from the fan bearings freezing and the fan itself running hotter then normal. Just depends on car maker design.

There is also a TIMER RELAY module incorporated in all CA equipped cars as part of the SMOG packaging for cars sold here in this state. Reason for that is to reset the pre-warm circuit properly when restarting the car back up after shorter run and stop trips. If this relay is bad it could cause the fan to run on longer then normal after shutting off the vehicle, thus causing undue wear and tear on the fan motor also. I used to think it also helped to clear out any fuel fumes from under the hood after running the engine, but could never prove it or have it verified by my own minivan maker when I owned a minivan??

NEVER DRIVE THE JEEP WITHOUT THE FAN MOTOR BEING CONNECTED!! You will surely damage something you don't want to!!!

To check the radiator fan circuit do the following:

I would first disconnect the battery from the circuit, and do any resistive type DVM meter checks first (unless you are unsure of how to do them), and then do the following checks below to check out the fan motor and related sensors/switches with power reconnected. If you have a lot of MEMORY type devices onboard your Jeep (Stereo, GPS, etc) you might want to use a simple 12-volt TEST LIGHT or again a good DVM to trace for a good ~12-volt battery voltage at point-to-point connectors instead, so as not to lose those memory settings.

First check the wiring leading to and from the fan motor itself and the TS (1 or possibly 2) connectors to make sure they are snapped together fully and making good connections. Also check the GROUND WIRE coming off the fan motor connector - as if this ground point is dirty or corroded causing a bad ground return path then the fan motor will appear to be dead as well.

Next check the fan itself for free-play. Is it turning freely or is it very tight or hard to spin?? If so - you have a bad fan and it's time to replace it NOW! (In your case it doesn't appear to be a bad fad fan motor at all.)

If you are handy with a digital volt meter (DVM) connect it in DC series with the fan motor and while running the Jeep measure the current and compare it to a new fan's rating. If it's excessive then the fan motor is on it's way out. Time to replace. (Skip this part too, as your fan is known good.)

VERY IMPORTANT STEP HERE - Also check those 1 or 2 TS switches to make sure they are in the OPEN setting with a COLD engine/radiator. CHECK AGAIN to make sure they CLOSE at the proper engine temp as well. If they don't close at or near 190 degrees F then one or the other (if there are 2 or more in your system) may be bad, and that may very well be your only problem.

If Jeep has added a FUSE or FUSIBLE LINK to the fan circuit make sure you check that part also. It's doubtful though, as the fan circuit is fairly simple by design. A Timer Relay type Switch would be downstream of the/any TS switch(es) by design as well, so I would place my money 1st on a bad TS switch, or a possible bad ground connection 2nd.

Does not appear to be anything else that excessive as it looks to just be isolated to the radiator fan circuit itself.

Hope this helps you out to troubleshoot the problem. Feel free to email me if you still have further ??'s.

Frank

AND THEIR REPLY WAS:

posted by djvanh on Aug 13, 2008

We are being told that it is the PCM that is causing the fan not to work. Can we replace the PCM with a remanufactured one?

Thanks

AND MY REPLY WAS:

I guess I better ask you a couple of ?'s before going any further here - as I'm not getting back any feedback at all as to what I posted previously.

No past history - no past to present attempted fixes - no troubleshooting feedback.....

The reason I say this is because now you are saying > We are being told that it is the PCM that is causing the fan not to work.

This has me asking - WHO is telling you that the Powertrain Control Module is supposedly bad? By WHO I mean - Jeep dealership - auto repair garage - your friend - who?

I need to know what steps you took to get to this new revelation point - as to the fan supposedly not working?

Please be very specific, and not just a 1 or 2 line reply - as that won't help me pinpoint the problem at all. After all - you have the SUV there (wherever you are located state/city wise), and I don't.

Also - do you have the/a service manual (Haynes or Chilton Auto Manual for your year & make Jeep)?

When I get your feedback we can proceed forward.

Thanks,

Frank



1 - Highly degreed in Electronics first of all.

2 - Worked for 2 SEARS AUTOMOTIVE STORES, one on the East Coast and the other one still being the largest SEARS AUTO in CHICAGO at 6-corners. I specialized in troubleshooting all auto electrical problems - including battery testing and charging system testing and repair. Graduate of DeVry in Chicago also!

3 - Troubleshooted, repaired, and replaced many water pumps, thermostats, fans, TS units, and radiators on all types of vehicles and makes and models. I hate those stupid internal water pumps on many of the *** Honda and similar autos as that is the dumbest design I've ever seen! Stay away from buying one of these headaches!! Timing belts (non-metal type) are just as bad!

Posted on Aug 21, 2008

  • 2920 Answers

SOURCE: cooling fans not working on 1995 camaro z28

you have a burnt fan relay...if it were my car i ould run a jumper to the fuse panel so that when you turn the key on the fan will also come on and run.its not hard to do and it will stop the car from overheating

Posted on Jan 24, 2009

  • 2 Answers

SOURCE: cooling fan switch/or sensor

The Coolant temp Sensor is located right under the top radiator hose (on the engine side), with a little black connector!, You might have to remove th etop hose to get to it with a deep socket and extension!.
Also Dont Forget to blled the coolant system by the bleeder valve uptop right near/above the coolant sensor!.(10MM Mini socket w/ extension IIRC!)

Posted on Sep 28, 2009

  • 1509 Answers

SOURCE: Both radiator cooling fans won't turn on vehicle overheats

The fans come on only when hot or the AC is on. There are many fuses that have to be good for it to work. The fan relay should have 2 pins hot with the key on, The other 2 should be ground. with the key off one should be hot and the other can then be ground the other pins that are ground one of them is the fan. the other becomes ground when the computer turns the fans on. If you don't have a pin thats hot at the relay all the time then theres a blown fuse or even the power wire from the battery at the battery

Posted on Nov 02, 2009

AutoDocP
  • 56 Answers

SOURCE: test radiator cooling fans

Hello,

they should come on at app. 90 deg. celsius (190 F) .

It is a common problem with the beetle, the cause is a malfunction in the cooling control module.

The module is surveilled by the on board diagnosis system, so you should bring the car to the shop and let them run some tests with the diagnosis computer.

Posted on Jun 26, 2010

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Radiator blew due to cooling fans not working, replaced radiator fans will not run unless I turn on ac or pull run rly fuse what is going on?


Check the sensor in the bottom of the radiator is connected and working.The water has to get hot before they come on near boiling point,the air con switch over ride s the normal sensor.

Oct 01, 2016 | 2007 Chevrolet Uplander

1 Answer

Why are my cooling fans for radiator running constantly?


The cooling fans are supposed to run any time the a/c is on in order to keep air flowing across the condenser. Your a/c will not work properly at idle if they quit.

Jul 27, 2015 | 2010 Ford Escape

1 Answer

Location of the temp.cooling switch /or sensor for radiator cooling fans on 2006 chrysler 300 c


The radiator cooling fans are controlled by the engine managment computer, it uses the signal from the Engine Coolant Temperature Sensor (ECT), unless the engine is hard starting or runs poorly the sensor is not the problem. Also the Check Engine light would be on, is that the case?

Apr 21, 2012 | Cars & Trucks

1 Answer

2000 daewoo leganza is overheating, leaking anti freeze, and water. what is wrong?


sound like thermostat sticking close.replace thermostat and radiator pressure cap.if already done.you could have faulty water pump.if engine overheating at long slow traffic line or setting at a stand still.the engine cooling fans should be running, check and see if cooling fans running if not,check cooling fans fuses and relays.if all is good,hot wire make sure coolings fans okay.if all is good,code scan vechicle for faulty engine coolant temperature sensor and ecm problems.you need a code scanner where you can check live data check see if coolant temperature sensor reading correctly if engine coolant temperature is 190 degrees the coolant sensor. the scanner suppose to show 190 degrees in temperature if not it reads 80 or 90 degrees the engine coolant temperature sensor is faulty need replacing.if all is good check engine oil if look like milk shake blow head gasket will cause over heating.to be on the safe side i would replace thermostat and radiator pressure cap first.to make sure engine coolant circulating through radiator and engine block.

Nov 15, 2011 | 2000 Daewoo Leganza

1 Answer

Overheating


CHANGE THERMOSTAT AND RADIATOR PRESSURE CAP.CHECK COOLANT LEVEL.MAKE SURE YOU HAVE 50/50 ANTIFREEZE AND WATER.MAKE SURE COOLING FANS COMING ON WHEN ENGINE REACHES 190 DEGREES.TO SEE IF COOLANT FANS RUNNING TURN ON CAR AIR CONDITIONER TO SEE IF FANS RUN IF NOT CHECK COOLING FANS FUSES.IF FUSES GOOD I AM LOOKING AT A FAULTY COOLANT TEMPERATURE SENSOR.IF ALL IS GOOD.NO LEAKS AT RADIATOR HOSES + HEATERS HOSES. NO LEAKS AT WATER PUMP WEEP HOLE OR GASKET.NO LEAKS AT RADIATOR.LAST RESORT CHECK ENGINE OIL. IF LOOKS LIKE MILK SHAKE YOU HAVE LEAKING HEAD GASKET.THAT WILL CAUSE ENGINE OVERHEATING.

Jun 23, 2010 | 2000 Cadillac Seville

4 Answers

Engine cooling fans are not working


You can check if the fans are working by turning on you Air conditioning. They should run constantly with the A/C on.
Also bear in mind that the fans do not normally come on until the coolant temperature hits around 225-228 degrees.

Apr 07, 2010 | 1998 Cadillac DeVille

2 Answers

198 mercury sable cooling fans motor


Cooling fans ( on radiator ) only come on when the engine reaches a certain (hot) temprature. There is a temp sensor threaded into the radiator end reservoir that switches a relay off and on that runs the fans. Either the temp sensor or the relay is probably bad. Normally , those fans will not be on if the car is moving , the air flow from just driving is sufficient to cool the rad. If you stopped and idled for a while , eventually the rad would heat up enough for the fans to come on.

Mar 31, 2010 | 1998 Mercury Sable

5 Answers

What would cause my radiator fans not to run


A lot of different things fall into this senario.Low coolant level,air in the cooling system,and a stuck thermostat,or,a bad coolant sensor,or even a bad cooling fan relay,or the cooling fans are bad.Turn the defrost on or the ac,the cooling fans should come on if the fans,and the relay are ok,if so,replace the thermostat,and coolant sensor,and bleed the cooling system of air.

Feb 01, 2010 | 1994 Toyota Camry

1 Answer

Radiator Cooling Fans won't run. Not seized up.


EIther fuse, relay, fan motor itself, temp sensor, or bad wiring

Oct 29, 2009 | 1998 Plymouth Grand Voyager

1 Answer

Electric fans do not run ...radiator cooling fans will not come on. I have installed new relays (3), new thermo-sensor and put in new thermostat and water pump but cannot run fans unless airconditioning is...


Che if you installed the right thermo sensor, check for broken wires and if the car has the wrong coolant sensor or the wrong thermo sensor it will not work right.

Jul 08, 2009 | 2002 Chevrolet Malibu

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

22 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cars & Trucks Experts

yadayada
yadayada

Level 3 Expert

76109 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers

Randy Ohler

Level 3 Expert

14585 Answers

Are you a Car and Truck Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...