Cooling fan issue

TPMPRODUCTIONS

MEMBER
2001 NISSAN SENTRA
1.8L
4 CYL
2WD
AUTOMATIC
81,250 MILES

So, I've had my car for about a year this month. Recently I noticed the cooling fan getting really loud when the car gets hot. On Friday the car started to overheat while waiting at a light. I knew the fan was the cause. After watching a few videos, I checked the voltage on all three cooling fan relays. I got 12 on all 3. Now I'm stuck. I don't even know which relay controls the high-speed function. Do I need to just replace the whole fan assembly? Sounds like it. Please help.

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

When you say the fan was loud, that leads me to think the fan motor was going bad. Does it turn on at all? If it does and is making noise, could you record it and upload it for me to hear?

As far as the relays, I attached the wiring schematic and relay locations in the box for you below. Note: I had to cut the schematic pics in half to make them readable. I did overlap them so you can follow from one to the next.

Here is a link you may find helpful as well. It explains how to test a relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Also, when the fans are off, spin them by hand to see if there is resistance or back and forth play that would indicate a bad bearing.

Let me know what you find or if you have questions.

Take care,

Joe

See pics below.

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Monday, December 20th, 2021 AT 9:14 PM

TPMPRODUCTIONS

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86 POSTS

Thanks for the advice. Now if the bearing is bad could I just change the bearing or do I need to replace the whole fan?

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Tuesday, December 21st, 2021 AT 11:11 AM

TPMPRODUCTIONS

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86 POSTS

Also, I added another question, but it's actually related to this. Now I'm having electrical issues with other things as well. After switching a relay to test if any of the fans were working, I started having issues with the keyless entry, power locks and back window defrost. Could there be a bigger malfunction at play here?

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Tuesday, December 21st, 2021 AT 11:14 AM

TPMPRODUCTIONS

MEMBER
86 POSTS
2001 NISSAN SENTRA
1.8L
4 CYL
2WD
AUTOMATIC
81,250 MILES

So, I currently have an issue with some functions of my car. I recently swapped a relay (Cooling Fan #1 and Keyless Horn) to check if my fan was malfunctioning. While they were switched my keyless entry did not work. I switched them back now I have a whole host of problems. My door lock switch stopped working, drivers and passenger side. My rear defogger button doesn't illuminate. The chime that happens when I put the key in the ignition stopped working. Update: after running my scan tool. The door locks magically work again. I did nothing but check the status of the locks. I also tried the defroster, but I noticed when I pressed it, it came on for half a second and I heard a click and it cut off. The click was from one of the relays under the steering wheel. Not sure which one. Anyone have an idea what might be going on here?

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Tuesday, December 21st, 2021 AT 11:30 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

As far as the fan motor, if the bearing is bad, replace the fan motor. Here is a link that explains how one is replaced:

https://www.2carpros.com/articles/replace-electric-fan-motor

Next, check fuse 15 in the fuse box in the vehicle. (See pic 1 below) When you check the fuse, make sure there is power to and from it. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know what you find.

Joe

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