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MY electric fan will not cut on on my 96 civic ex. Is there a weak link in the sensors or do I just have to test them all. DOes anyone know of a website or anythng that can help me test them.
 

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Adia's Daddy
2004 Honda Element
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MY electric fan will not cut on on my 96 civic ex. Is there a weak link in the sensors or do I just have to test them all. DOes anyone know of a website or anythng that can help me test them.
It could be a few things:

  1. Thermoswitch failure
  2. Fan motor(s) failure
  3. Cooling fan circuit issue/failure.
I'm tired and my brain is mush from being at work from 8am-830pm today so my apologies if I'm not very clear or concise with this. I attached come scans from my own Honda 1995 Civic Service Manual. There is one for fan control systems without A/C and one for fan control systems with A/C. The wire colours may be slightly different but the fuse and relay locations will be similar and are indicated on the respective fuse/relay box covers:

Fan Controls Without A/C


Fan Controls With A/C


Fan Motor Test



Here is my fun little attempt to help out and walk you through it Honda troubleshooting style :TU::

1. Are there any blown fuses in the under-hood or under-dash fuse boxes?

  • YES - Replace blown fuse(s) and re-check. If fuse blows again, troubleshoot and repair a short in that circuit first, the re-check.
  • NO - Continue to step 2
2. Run the engine until it has fully warmed up (keep a close eye on the temp gauge). Does the fan come on?

  • YES - Intermittent failure. System is okay at this time (LOL sorry, inside Honda technician joke :greddy: )
  • NO - Continue to to step 3.
3. Unplug the engine coolant temperature switch connector (ECT switch is located in the thermostat housing) and insert a jumper wire into the connector. Does the fan turn on with the connector jumped?
  • YES - Faulty thermoswitch. Replace.
  • NO - Continue to step 3
3. With the key ON, engine OFF and the ECT switch jumped, unplug the connector at the non-functional fan motor and check for battery voltage and ground up to it with a test light. Is there battery voltage and ground?

  • YES - Faulty fan motor. Replace.
  • NO - Troubleshoot for an open or failed relay in the fan motor circuit.
You can also test the fan motor as per the manual by applying battery power and a good ground to the motor connector itself and seeing if the fan runs. However I find it's a teeny bit easier (and admittedly a lot more fun :)) to get my test light or logic probe out, jump the ECT and see what I have where.

Honestly, assuming the fuses and relays are good, you'll probably find that it's either your fan motor or your ECT switch. I've already replaced my ECT switch once on my Civic.
 

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Adia's Daddy
2004 Honda Element
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Engine doesn't have to be warm to jumper the fan switch on the thermostat housing to check.

First step though.
Wow it's time for bed for me I think :wacko:.

My bad Bone. I edited the post a bunch of times copying and pasting and didn't even notice that. You're right you don't need to have it warm to jump it. It should be checked for operation first once the car is warmed up, but after that if the fans still don't kick on, then you can jump it and go from there whether the engine is hot or cold.

Actually now that I think about it, unless you're working in a cold garage and want a warm engine in front of you, it's probably better to wait for the engine to cool down to start troubleshooting things under the hood.
 

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Brokedick Millionaire
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don't "hardwire" it, but a switch parallel to the OEM fan switch.

That way you have manual control and OEM control.

Needed if you have a cracked head, my second in same car.
 

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Lifetime Awesome Member
'89 CRX HF
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25,544 Posts
don't "hardwire" it, but a switch parallel to the OEM fan switch.

That way you have manual control and OEM control.

Needed if you have a cracked head, my second in same car.
But make sure your "hardwired" switch is keyswitch power. Back when mine was hardwired I left the fan running several times after I was out of the car and doors were locked. Luckily I never forgot totally and ran the battery dead.
 

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Adia's Daddy
2004 Honda Element
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3,364 Posts
But make sure your "hardwired" switch is keyswitch power. Back when mine was hardwired I left the fan running several times after I was out of the car and doors were locked. Luckily I never forgot totally and ran the battery dead.
If you put the switch in parallel with OEM fan switch, it is always switched power.
Made a Paint diagram from the one schematic to show how to wire it.

I respect your knowledge and good eye Bone so if I put the switch in the wrong position, feel free to make corrections :TU:. I know the ECM/PCM is spliced in parallel with the ECT so I assumed the switch should be downstream of it to ensure the ECM sees it as proper ECT switch operation.

If you have A/C, I believe the switch is still wired in the same position, that being pre-ECT and post-ECM splice.

 

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