Cooling fans not working

Tiny
MONEYCOUNT
  • MEMBER
  • 2001 HONDA ACCORD
  • 1 MILES
Radiator fans are not coming on and just noticed that the coolant temperature sensor is broken. Fuses are not blown, not sure about fan relay though. Question is. Does the sensor operate the fans? Or could it be the relay or a short in the circuit somewhere? The fans do operate by jumping battery direct. Any help is greatly appreciated.
Wednesday, February 27th, 2013 AT 7:44 AM

28 Replies

Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Greetings

The coolant temperature sensor lets the fan's relay know when to open and close the circuite, so if the sensor is bad then it will not allow the fans to operate.
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Wednesday, February 27th, 2013 AT 7:55 AM
Tiny
MONEYCOUNT
  • MEMBER
  • 27 POSTS
Now on the 2001 Accord the coolant sensor is the broken sensor I have (which is on the side of the block) and not the sensor on thermostat housing correct?
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Wednesday, February 27th, 2013 AT 8:25 AM
Tiny
MONEYCOUNT
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  • 27 POSTS
The one on the thermostat is to signal the gauge right?
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Wednesday, February 27th, 2013 AT 8:28 AM
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
The sensor near the thermostat is for the temperature gauge, yes. The 2001 accord actually has a radiator fan switch, not a sensor (image below). Is this the part you are talking about being broken?
Image (Click to make bigger)
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Wednesday, February 27th, 2013 AT 8:38 AM
Tiny
MONEYCOUNT
  • MEMBER
  • 27 POSTS
The one that is broken according to the diagram is the Engine Coolant Temperature Sensor(ECT). So your saying that its the Radiator Fan Switch thats bad? Because where it shows the Coolant Temperature Gauge Sending Unit here I dont have that. There's just a plug there.
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Wednesday, February 27th, 2013 AT 9:18 AM
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Yeah, the coolant temp gauge sending unit is only for the 98 and 99 models, the ECT sensor replaces that sending unit on your model so you will have the ECT sensor and the fan switch. The best place to start diagnosing a faulty fan would be fuses and the relay though as they are the cheapest and easiest to test. But since the ECT is bad on yours, that is most likely at fault.
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Wednesday, February 27th, 2013 AT 7:40 PM
Tiny
MONEYCOUNT
  • MEMBER
  • 27 POSTS
Ok, great. Im replacing the ECT now and hope thats it. The fuses and relay are fine. So if after replacing the ECT and fans still dont come on then its probably the fan switch correct? I'll keep ya posted. Thx
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Wednesday, February 27th, 2013 AT 8:17 PM
Tiny
MONEYCOUNT
  • MEMBER
  • 27 POSTS
The fan switch which is the one on top of the thermostat housing right?
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Wednesday, February 27th, 2013 AT 8:21 PM
Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Yes, that is correct. The switch is on top of the tstat housing as shown in the previous graphic. Let me know how it goes.
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Wednesday, February 27th, 2013 AT 8:24 PM
Tiny
MONEYCOUNT
  • MEMBER
  • 27 POSTS
I sure will. And once again THANKS for all the advice! :)
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Wednesday, February 27th, 2013 AT 8:27 PM
Tiny
NEWYORKER52
  • MEMBER
  • 1 POST
  • 1999 HONDA ACCORD
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 123,000 MILES
I have 1999 Honda Accord with 123K miles. The radiator fan is not working properly; the fan motor goes on before the engine is on. I have noticed when the motor goes on and off a clicking noise is coming. I checked coolant level which is OK. I have tried a new relay but this did not fix the problem. Do you have any suggestions? I am hoping this is something minor and a simple fix. Thanks for any help you may have for me.
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
FISHERMAN
  • MECHANIC
  • 937 POSTS
Hello !

Check the thermo-switch (radiator fan switch)( that switch turn on and off the cooling fan as soon as the temperature reaches the specific temperature in this case:196-203 degrees F.)

good luck!
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
FISHERMAN
  • MECHANIC
  • 937 POSTS
Hello Again.

The radiator fan switch its located on thermostat housing.

If you need the wiring schematic just let me know!

Good Luck!
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 1999 HONDA ACCORD
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 85,000 MILES
1999 Honda Accord mileage 85,000. Today when I was driving to work I had the A/C on. After a while of being stuck in traffic I turned off the A/C since it was really cold inside the car. After five minutes of stop and go traffic, I looked down to my board and saw the temperature needle rising tours the hot area. I immediately stopped and opened the hood. I noticed that for some reason the cooling fan were not working. I went back to the car and shot off the engine. As soon as I took the key out the cooling fan started working. Then I put the car in switch and the cooling fan stopped working again. I waited for the car to cool off and then I started the car and turn on the A/C. After this, both of the cooling fans started working. I turned off the A/C and left the car running. After three minutes the car started overheating again and I repeated the same operation. Turn on the AC/ and the fans started working. I turned off the AC and left the car running and it started overheating again. The cooling fans at no point came on. I then turned off the car and the fan started working. I checked the cooling fan fuse and it's okay. I checked the cooling fan relay under the hood since I have had the same exact problem with an 1989 Accord LX-I I had own previously and it ended up being the cooling fan relay. The power window relay and the cooling fan are exactly the same. I swapped relays just to se if the problem could off been the relay but not even with the relay swap the fans worked. After I swap the relays I started the car again and let it run and it started overheating again. I put the relays back where they belonged and just drove off to work with the A/C on.
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
You probably have a temperature sensor that has failed. This can be verified by scanning the computer.
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
THEDA
  • MEMBER
  • 1 POST
  • 1994 HONDA ACCORD
  • 4 CYL
  • AUTOMATIC
  • 145,000 MILES
I just purchased a 94 Honda accord and the A/C is not working and I seen there was no coolant so I went and got coolant put it in and and then noticed the fans are not going. I don't know much about cars. What could it be?
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
The cooling fans do not work upon starting vehicle. They only work when a certain temperature is reached and that triggers the cooling fan switch to activate the cooling fan relays and cooling fans.
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
IGGY1969
  • MEMBER
  • 3 POSTS
  • 1996 HONDA ACCORD
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 157,000 MILES
Recently my car overheated, then I changed the thermostat and it runs great, it does not overheat anymore but the cooling fans do not turn on.I also tested the fans motors directly from the battery and they do work, also checked the fuses and they're fine, so I think it could be either the fan switch or the cooling fan control. What can you tell me?
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Could be the engine coolant temperature sensor/relay and computer controlled of the relay
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)
Tiny
IGGY1969
  • MEMBER
  • 3 POSTS
I've checked the relays under the hood behind the glove box, switching the power windows relay with the fan relay, they seem fine.
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Monday, June 3rd, 2019 AT 6:12 PM (Merged)

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