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04 Monte Carlo ls fans not working

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Old Feb 3, 2026 | 04:13 PM
  #1  
Lerry's Avatar
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Joined: Jun 2024
Posts: 1
From: Columbia Tennessee
Default 04 Monte Carlo ls fans not working

At least I think they’re not. I know the one that goes for the air conditioner when you turn it on is not working. I have checked all the relays for power continuity everything good I checked the ground. If I jump both fans directly to power and ground source they work if I unplugged my temp sensor they will automatically kick on. I’ve let the car run for 30 to 45 minutes to let the temperature get up and get up to around 210 to212 the fan. Still don’t kick on. I am checking it with an OBD two scanner and the temps match
 
Old Feb 9, 2026 | 01:16 AM
  #2  
volkerc's Avatar
Joined: Feb 2013
Posts: 136
10 Year Member
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Fan turn-on temps

For the 2004 3.8L Monte Carlo, the factory thresholds are roughly:
  • Low-speed fan: ~223°F
  • High-speed fan: ~230–235°F
  • Fans OFF again: ~216°F
So at 210–212°F, the PCM is not supposed to turn the fans on yet.
 
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