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1999 Honda Civic LX
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10 Posts
Discussion Starter · #1 ·
Okay I know there are probably tons of threads about this but I'm new to the forum and dont want to search forever...
So my problem is the Radiator Fan doesn't kick on once car is definitely at/above running temp. I just installed a new Fan Switch on the Thermostat Housing after taking a wire and jumping the plug to see if the fan actually works, which It does. After new Switch was installed it still failed to kick on. The fuse and relay under hook are both working properly.
Now where do I go from here?? I'm getting tired of messing with it and cant find anyone to help or give knowledgeable advice on fixing the problem..
PLEASE HELP!!!! Thanks in advance for any helpful advice馃檹馃徏 I can try giving more Info if needed.
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zee
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Brokedick Millionaire
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A) How did you jump the switch
B) How long did you let the car warm up and get to temp?
 

Registered
1999 Honda Civic LX
Joined
10 Posts
Discussion Starter · #3 ·
A) How did you jump the switch
B) How long did you let the car warm up and get to temp?
With a small wire, not on the switch itself though I meant on the plug that connects to the switch. So then the fan will run constantly when the car is on. And I let it run for a good 10 to 15 minutes. The temp gauge barely goes up, so maybe that could have something to do with it?
 

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93 Civic HB SI
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1,697 Posts
Broken wire near/in the connector? Pins in the connector worn/corroded/etc?

I've seen plenty of times where jumping something works because the jumper wire fills the terminals in a different way compared to the pins in your switch, allowing the terminals to make contact when the switch pins dont/can't for some reason.

Also be aware that sometimes when components are in their installed positions, the wires, pins, connectors are in their installed/relaxed state. If a wire is broken/barely hanging on/broken inside the insulation, when you unplug the connector and flip it 180 to put a jumper wire in it you might falsely reconnect the break and appear everything works, but then it quits working back in its resting/installed position.

All that might initially believe you to think the circuit is all good, but pins/terminals/wires are still part of the circuit and have many unique ways that they can fail :)

If you believe wiring/pins/terminals are good, a quick way to test, and I know it might suck because you will lose some more coolant, undo the switch from the housing, plug it back into the connector (if you think the pins/terminals are good), remove or shield the o ring around the switch, then use a lighter, heat gun or torch on a LOW setting while you hold the plastic part of the connector to see if you can get the fan to come on with direct heat. That will prove out the switch is capable of turning on the fan.
 

Registered
1999 Honda Civic LX
Joined
10 Posts
Discussion Starter · #6 ·
why did you install a new fan switch?

maybe its just not getting hot enough..
both rad hoses hot?
do you have a fancy laser temp checker?
scantool or someshit?
Yeah both rad hoses get hot. But no I dont have a laser temp checker thingymajigger. I could take my car to autozone and have them hook it up to their scan tool.
Broken wire near/in the connector? Pins in the connector worn/corroded/etc?

I've seen plenty of times where jumping something works because the jumper wire fills the terminals in a different way compared to the pins in your switch, allowing the terminals to make contact when the switch pins dont/can't for some reason.

Also be aware that sometimes when components are in their installed positions, the wires, pins, connectors are in their installed/relaxed state. If a wire is broken/barely hanging on/broken inside the insulation, when you unplug the connector and flip it 180 to put a jumper wire in it you might falsely reconnect the break and appear everything works, but then it quits working back in its resting/installed position.

All that might initially believe you to think the circuit is all good, but pins/terminals/wires are still part of the circuit and have many unique ways that they can fail :)

If you believe wiring/pins/terminals are good, a quick way to test, and I know it might suck because you will lose some more coolant, undo the switch from the housing, plug it back into the connector (if you think the pins/terminals are good), remove or shield the o ring around the switch, then use a lighter, heat gun or torch on a LOW setting while you hold the plastic part of the connector to see if you can get the fan to come on with direct heat. That will prove out the switch is capable of turning on the fan.
Actually after replacing the switch I got looking at the wiring cause it just didn't look factory to me (too much electrical tape and wires pulled way too tight) so i stripped all the electrical tape off and I find the wires had been cut and been twisted back together very badly.
I redone the wiring as it should have been done, but it didn't fix anything. The fan still wont kick on. I can hear the relay click when I jump the plug and the fuse isn't blown as I had checked continuity with my DMM.
I also tried checking continuity on the plug that is beside the radiator reservoir and it doesn't have continuity. So I'm not sure what to do next?
 

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1999 Honda Civic LX
Joined
10 Posts
Discussion Starter · #10 ·
yea but does it still open, ie rusted/jammed shut/open if its jammed open it will take quite awhile for the car come up to temp
Well that I don't know. I'd have to take the thermostat off to check wouldn't I?
 

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The radiator fan relay should have four connection if you remove the relay.
Pin 1 (12v) from fuse via battery
Pin 2 receive (12v) from pin 1 when relay energizes
Pin 3 receives (gnd) from radiator fan switch when thermostat reaches temperature
Pin 4 (12v) from fuse via ignition switch
So pins 3&4 will energize relay and cause the wiper arm to make pins 1&2.
I would verify if I am getting these actions to happen. I would first verify 12volts is at pin 1, then turn ignition on and verify 12 volt on pin 4. Then if good start car and verify pin 3 gets ground when it reaches approx 210 thermostat temp.. If that all worked then you would chances are have a bad relay. But if you were to put a jumper wire across pins 1&2 instead of using the relay and your fan comes on your wiring is good, does not come on bad wiring.
 

Brokedick Millionaire
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40,743 Posts
The thermostat doesn't open until fan kicks on?
T-Stat starts to open 30+ degrees F before the fan will kick on.
@168-170 the T-stat is starting to open, at 205 the fan kicks in.
 

Brokedick Millionaire
Joined
40,743 Posts
With a small wire, not on the switch itself though I meant on the plug that connects to the switch. So then the fan will run constantly when the car is on. And I let it run for a good 10 to 15 minutes. The temp gauge barely goes up, so maybe that could have something to do with it?
A paper clip is best to jump the connector. With it jumped, heater valve opened, the car will take forever to get to temp.

On the race car I just bought, the fan switch isn't working nor the temp gauge. but it got hot, you know the smell after 25 years. I'll be installing a mechanical gauge (no need for ignition to be on) and a manual fan switch to control the temps while staging. This is an old trick I used when drag racing my EG HB.

Hit the burnout box at 155-160, stage at 170, ECU is out of cold start loop so one the normal fuel/timing maps. There is a .25-.3 second ET difference between being too chilled and at the just right temp. But that was back in the late 1990's :)

<<< old fart on DSO :)
 
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