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Discussion Starter #1
Hey guys,

So my radiator fan isnt turning on. I have jumpered the ECT switch using a paper clip and turn the ignition on and the fan didnt start. So my guess is it might be the relay.

Looking the relay/fuse box, I am not sure which one is for radiator fan.

Could anyone please help me in right direction?

Thanks
 

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Tap the radiator fan motors. That's what I do on Toyota's at my dealership. They will kick on most of the time. Make sure you're at operating temp or keep it jumped like before, then tap. Good luck!
 

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There are 2 fans. Cooling fan and AC condenser fan. Right side is the condenser fan and left side is the cooling fan for your cooling system (not too sure). Which one isn't running? Your Cooling fan should not turn on if your engine is not over operating temperature threshold. Your A/C condenser fan, along with your A/C compressor clutch, should engage when pressure is needed by your A/C system and disengage if there is enough pressure in the system.

To test each fan, you can jump each fan through the connectors (located on the fan shroud, should be clipped on the shroud) straight from the battery using test leads and proper probes. If both fans turn on, fans are then okay. Now you will have to look for an open in the circuit of each fans. Fuse for A/C condenser fan is UNDER-HOOD # 6 20AMP and Rad fan is Fuse 7 20A for M/T and 30A for A/T. If fuses are ok, test the both relays, see your owner's manual for it. CONDENSER FAN RELAY AND RADIATOR FAN RELAY.

Also Check the following fuses:

UNDERHOOD: FUSE# 11 AND 15
UNDERDASH: FUSE# 36

PLEASE FOLLOW THIS STEP BY STEP.

Most probable cause is you have a blown fuse for your radiator fan AND/OR a stuck open (circuit open) radiator fan relay. It could also be bad ECT 1 (Engine side) and/or ECT 2 (radiator side) sensors but they rarely go bad. WORST CASE SCENARIO, your ECM may have to be substituted with a known good unit if none of these fixes it.

Hope this bit of information works for you. I tried my best to go through the electrical schematic with the information you supplied.
 

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Discussion Starter #7
thanks guys for the information.

The radiator fan turns on when the a/c is turned on, so the fan is working good. Its only during normal operation, fan doesnt come on.

The weird thing is the ECT temp switch hasnt gone above 8 bars even with fan not turning on. Could it also be a faulty temp sensor? Shouldnt the temperature rise with the fan not working? After 2-3hrs of cooldown, I can sense the heat on the hood. That tells me the engine is overheating..

I cannot find a relay diagram in my owners manual that says " radiator fan relay". I will take picture tonight of both the fuse box and owners manual. May be you guys can direct me.

Thanks again
 

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thanks guys for the information.

The radiator fan turns on when the a/c is turned on, so the fan is working good. Its only during normal operation, fan doesnt come on.

The weird thing is the ECT temp switch hasnt gone above 8 bars even with fan not turning on. Could it also be a faulty temp sensor? Shouldnt the temperature rise with the fan not working? After 2-3hrs of cooldown, I can sense the heat on the hood. That tells me the engine is overheating..

I cannot find a relay diagram in my owners manual that says " radiator fan relay". I will take picture tonight of both the fuse box and owners manual. May be you guys can direct me.

Thanks again
If your temperature gauge does not raise to where it used to be, then you have a bad thermostat and/or water pump (most likely thermostat only). This is probably the reason why your coolant does not get warm enough to trigger the fan switch
 

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Discussion Starter #10
When I unplugged the ECT#1 sensor, the engine temperature maxed out. The engine was actually cold, but I am assuming since it was not getting a signal from the sensor thats why it maxed out. Shouldnt that send a signal a turn on the radiator fan?

I saw you mention that civics have 2 temp sensors. Does the radiator fan need to get a signal from both the sensors to start or just the engine sensor?

I am pretty new at this, so I apologize for any obvious questions.
 

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And or turn on a\c to see if that operates the fan
hey bro, so i have already replaced the etc sensors located on the head and on the radiator. still no luck they are oem. also new thermostat. tried it all my fans still only come on when i cross the wires. relay checks out fine, but even with my ac on they won't kick on what could it be???
 

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There are 2 fans. Cooling fan and AC condenser fan. Right side is the condenser fan and left side is the cooling fan for your cooling system (not too sure). Which one isn't running? Your Cooling fan should not turn on if your engine is not over operating temperature threshold. Your A/C condenser fan, along with your A/C compressor clutch, should engage when pressure is needed by your A/C system and disengage if there is enough pressure in the system.

To test each fan, you can jump each fan through the connectors (located on the fan shroud, should be clipped on the shroud) straight from the battery using test leads and proper probes. If both fans turn on, fans are then okay. Now you will have to look for an open in the circuit of each fans. Fuse for A/C condenser fan is UNDER-HOOD # 6 20AMP and Rad fan is Fuse 7 20A for M/T and 30A for A/T. If fuses are ok, test the both relays, see your owner's manual for it. CONDENSER FAN RELAY AND RADIATOR FAN RELAY.

Also Check the following fuses:

UNDERHOOD: FUSE# 11 AND 15
UNDERDASH: FUSE# 36

PLEASE FOLLOW THIS STEP BY STEP.

Most probable cause is you have a blown fuse for your radiator fan AND/OR a stuck open (circuit open) radiator fan relay. It could also be bad ECT 1 (Engine side) and/or ECT 2 (radiator side) sensors but they rarely go bad. WORST CASE SCENARIO, your ECM may have to be substituted with a known good unit if none of these fixes it.

Hope this bit of information works for you. I tried my best to go through the electrical schematic with the information you supplied.

your ECM may have to be substituted with a known good unit if none of these fixes it.... what do you mean? I've tried it all man and nothing is working.
 

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your ECM may have to be substituted with a known good unit if none of these fixes it.... what do you mean? I've tried it all man and nothing is working.
I got the same issue with my honda civic 2007
fan are getting on when A/C is on
Changed ECT ( both )
Still the same situation ?
Did you get any chance to solve you issue ?
 

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Hey guys,

So my radiator fan isnt turning on. I have jumpered the ECT switch using a paper clip and turn the ignition on and the fan didnt start. So my guess is it might be the relay.

Looking the relay/fuse box, I am not sure which one is for radiator fan.

Could anyone please help me in right direction?

Thanks
Hey
Were you able to solve your issue ?
 

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Test the fan when disconnected. Daughters civic condenser fan went out last summer. Caused lots of secondary damage. Fan was bad. Replaced along with AC repair been working well since.

Relays and sensors are a good thing to check but fans go bad as well.


Sent from my iPhone using Tapatalk
 

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Test the fan when disconnected. Daughters civic condenser fan went out last summer. Caused lots of secondary damage. Fan was bad. Replaced along with AC repair been working well since.

Relays and sensors are a good thing to check but fans go bad as well.

Sent from my iPhone using Tapatalk
I checked everything but car is still overheating I can check it via ODBII
Fan are good Once I started the AC the fans are both on, but they do not start while I am driving

For now, I am starting them using the AC.
 

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Test the fan when disconnected. Daughters civic condenser fan went out last summer. Caused lots of secondary damage. Fan was bad. Replaced along with AC repair been working well since.

Relays and sensors are a good thing to check but fans go bad as well.

Sent from my iPhone using Tapatalk
I checked everything but car is still overheating I can check it via ODBII
Fan are good Once I started the AC the fans are both on, but they do not start while I am driving

For now, I am starting them using the AC.
 

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I don't have much insight to add, but the same things happened with my 07 Civic recently. Fans wouldn't come on, or would only randomly decide to come on very infrequently, regardless of engine temp. Car was overheating as well. I changed both ECTs, thermostat, and was going to go after the relays, but never got around to it. The underside of your fuse/relay box lid should have a diagram for your relays. Mine does, at least.
 

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I don't have much insight to add, but the same things happened with my 07 Civic recently. Fans wouldn't come on, or would only randomly decide to come on very infrequently, regardless of engine temp. Car was overheating as well. I changed both ECTs, thermostat, and was going to go after the relays, but never got around to it. The underside of your fuse/relay box lid should have a diagram for your relays. Mine does, at least.
I am exactly in the same situation Did everything changed but still the randomly fan start
Were you able to fix it ?
 

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I am exactly in the same situation Did everything changed but still the randomly fan start
Were you able to fix it ?
I was not able to fix it. Took it in, found out I had 3k worth of engine damage and haven't touched it since. The shop did say my MAF sensor wasn't working right, but that's it. Everything else checked out according to their diagnostics (except the engine).
 
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