Radiator fan isn't kicking on?

Tiny
MRFOX
  • MEMBER
  • 1993 BUICK CENTURY
  • 3.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 157,000 MILES
Radiator fan isn't kicking on replace the fan motor the temperature gauge is still working fine was wondering if anyone had a picture of the relay diagram feel like that is what the problem is
Tuesday, September 23rd, 2025 AT 8:28 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi:

I attached the wiring schematic for the fan. First, confirm there is power to and from the AC/Eng fuse on the right side fuse panel inside the vehicle. If that checks good, we need to go to the relay and confirm power is always present on either pin 87 or 30. One of the two will have power at all times. If they don't, then we likely have a bad fusible link.

Additionally, I attached a pic of the fuse box and highlighted the fuse to check. Also, I attached a pic of the fan relay, which are located under the hood on the firewall.

Let us know what you find or if you have other questions.

Take care,

Joe

See pics below
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Wednesday, September 24th, 2025 AT 8:01 PM
Tiny
MRFOX
  • MEMBER
  • 3 POSTS
I appreciate it man, I figured out it is the coolant temperature sensor, I unplugged it and kicked the a/c on and fan started working perfect. When I pulled the old one the connector piece fell apart in the socket.
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Thursday, September 25th, 2025 AT 3:08 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Glad you could get it fixed, thanks for letting us know.
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Friday, September 26th, 2025 AT 8:54 AM
Tiny
MRFOX
  • MEMBER
  • 3 POSTS
Alright so I changed the coolant temperature sensor, and let the car get to roughly the temperature the fan is supposed to kick on at and it still doesn't but if I unplug the sensor fan fires right up, I'm lost on what to do next
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Saturday, September 27th, 2025 AT 3:30 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
The fan kicks on when the sensor is disconnected which is normal.

Coolant temp really hot enough? These engines don’t always trigger the fan until they’re very warm. Use a scan tool or infrared thermometer at the thermostat housing to confirm you’re actually at 220°F+. Don’t rely only on the dash gauge.

Thermostat working? If it’s stuck open, the engine may never get hot enough to reach fan-on temp.
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Sunday, September 28th, 2025 AT 10:27 AM

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