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Fan not coming on without AC on

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Old Jan 14, 2026 | 10:27 AM
  #1  
jeepwm69's Avatar
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Default Fan not coming on without AC on

Got my new head installed, everything back together with new water pump, timing belt, etc. Had to solder new capacitors on the ECU to get the code 15 to go away.

https://www.hondaaccordforum.com/for...68/#post402932

Drove it to work this morning for the first time, and the ONLY things that need to be addressed are a noisy P/S pump (will probably just replace with a used one from ebay, and my engine fan doesn't come on. If I turn the AC on, both fans come on, but with the AC off, the temp gauge will climb up a little over the middle of the gauge and neither fan comes on. Is that supposed to come on based on the engine temp sensor on the passenger side front of the head? I broke that sensor removing the head, and had to order a replacement and I'm wondering if I got a bad sensor.
 
Old Jan 19, 2026 | 06:41 PM
  #2  
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The switch on the front of the head with a green connector turns on the fan when the engine is not running to prevent heat soak. The switch you need to inspect has a green connector near or on the thermostat housing. That switches the fan on at a set temp when the engine is running. If you need to replace the sensor, make sure you get the correct sensor as those two sensors turn on at different temps. IIRC, 199F when engine is running and 210F when engine is off to stop heat soaking.

You can unplug the temp switch on the thermostat housing, start the engine, then short the two pins on the electrical connector. If both fans turn on, then you likely have a bad temp switch.
 
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