Nissan Repair: Cooling fans are not coming on.

Question
Hi Calvin, I have a 2001 Sentra SE 2.O and the cooling fans are not coming on. I was alerted by my temp gauge, but there was no other sign that it was overheating.... it was cool to the touch and I even removed the cap without any issue or release of pressure. I checked the fuse under the hood and it was fine.  Can you suggest how I should go about troubleshooting the system? I was going to pull and replace the 3 relay switches but that is simply taking a wild guess and they seem a bit hard to unplug.  Any suggestions would be greatly appreciated. Thanks so much.

Answer
Hi Tim -

There are several components of the cooling fan system:

1. Cooling fan motors
2. Fuse(s)
3. Relays
4. Temperature sensor (sending unit)

These need to be checked logically in order to find what is causing it not to work. You will need a multimeter (voltmeter) or a 12V test light and probe, and a jumper wire. I do not know your depth in car repair or whether you want to attack this on your own. I can guide you step by step if you have the tools.

Basically the fans work when you turn on the A/C or when the engine reaches a certain temperature. Checking the fan motors for voltage when you turn on the A/C will be your first test. If there is voltage but your fans do not work, replace the fan(s). If there is no voltage, then this is where the expertise comes in.

Let me know and I can instruct further if you want to tackle this yourself.

hope this helps -
aloha
'Calvin