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Radiator fan doesnt turn on

65K views 37 replies 19 participants last post by  bladerider8411  
#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
 
#11 ·
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???
 
#5 · (Edited)
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.
 
#12 ·
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.
 
#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
 
#8 ·
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
 
#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.
 
#15 ·
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.


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#16 ·
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.
 
#18 ·
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.
 
#21 ·
Sensor for regular fan is located at bottom of radiator. The relay in the under hood fuse box controls the switching. Test fan by manually powering it up. If it spins up likely a bad relay or sensor. Check wiring if suspected.


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#22 ·
My fans aren't working either,I tried to jump the wires nothing,tap on fans nothing.I ordered one relay and two diodes for under the hood fusebox,no change,among fan related and other fuses,new thermostat,new temp sensor,clutch relay,even new ac compressor.There is a fan relay under the glove compartment I also replaced,the ac and heater works now.It has a resistor that's blown,it can be replaced I found out after I bought the relay.
 
#23 ·
Ok so I'm answering the radiator fan issue.After this work at replacing parts,I decided to give the Mechanic this repair.And sure enough it was the Batterry,Alternator also was not charging the Battery,and the ac wasn't spinning,so he put the old ac back in,and refilled it so the fans started working.
 
#30 · (Edited)
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
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!
 
#31 ·
Hello everyone. For me, the fan only runs when I have turned on the air conditioning, but then only the air conditioning fan. If the air conditioning is off, then the air conditioning fan only turns on alone, but also only at 106C, for example. The engine fan never turns on. I drive a Civic 1.8 R18a2 from 2008. Which fuses should I change and check?
 
#35 ·
I'm sorry. My comment on this thread was my very first. I just created this account because I purchased a 07 Honda Civic for my sister. The Air Conditioner is running hot and I have done just about everything I could find online to fix it. Unfortunately, I don't have the cash to take it into the shop at the moment. As a last resort, considering it's hot and humid here in Tennessee I was just hoping someone on the site had a solution so I could get it fixed and deliver the car to my sister. Normally, I would just deliver her the car and hand her the keys but she has some health issues (medications make her sensitive to heat) and that's why I'd like to get the AC fixed before I deliver the car to her. I was hoping maybe hearing your solution would help. I understand your frustrations though. I apologize for leaving a comment that may have sounded rude or came off the wrong way. It's been a long time since I participated in forums. My email is my user name just add the @GMAIL.COM to the end. I would really like to talk to you regarding your solution if that's possible. As for helping others in the forums... I don't know how much help I can offer. I know the Toyota Prius 2nd Gen like the back of my hand and love them (I have 4) but this Civic so far has been a nightmare to work on and diagnose. Thanks in advance for any assistance you can offer. Sorry if this sounded like a sob-story... Not my intentions.
 
#36 ·
My fuse box missing motor fan relay , and I have temperature gauge up &down , on this case is it possible that this is the cause of the of not turning the radiator fan & I notice the engine are not overheating but when I run 12 miles it suppose to turn on the fan also when I turn on the ac still not turn on the radiator fan , is there someone know the issue? Thank you guys