# Fans still don't go on. Help needed.



## supernissannx (Mar 1, 2005)

I posted one thread on this earlier, so here is an update for today.

I have a 93 Nissan NX 1600 5-spd. My problem is the fans. They wouldn't go on, causing me to overheat. As of right now, i'm running the fans straight from the battery. So far I have checked both of the fan motors, and the relay. Both seem ok to me. I'm unfamiliar with the temp. sensor (never dealt with it before). Could someone please tell me where it is located? Also if you have had such a problem before, what was your solution? And also how do I check the relay and or the harness it goes onto? I tried shortcurcuiting the harness on where the relay goes onto, but nothing happened... did I do it wrong? It is summer, and hot engine is not a good idea. Thank you


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## gtlaw (Jun 24, 2005)

you could wire the fans to a switch and run them yourself 1) to see if it overheats even while the fan runs 2) if it does keep you from overheating you will be able to safely drive without ruining the engine untill you get it figured out


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## supernissannx (Mar 1, 2005)

exactly what i'm doing it right now, though i hook them up to the battery when i go on a trip 3+ miles long. I need ideas to figure out what is wrong, that's why I posted the thread in first place...


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## mille-16i (Jun 16, 2004)

do not wire the fans to a switch that is silly laziness. the fan switch is normally located on the radiator itself trace the wires back from the fans and you should be able to find it remember this is general vehicle knowledge not specific to your NX so nissan may have hidden it else where you should have 3 temp sensors on your car one for the dash(temp sender either on head or intake mine is by distributor E16i) one for the ecu(temp sensor normally located by thermostat) and one for the fans (fan switch normally on radiator lower pass side) so be sure you are checking and replacing the correct one good luck.


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## mille-16i (Jun 16, 2004)

gtlaw said:


> you could wire the fans to a switch and run them yourself 1) to see if it overheats even while the fan runs 2) if it does keep you from overheating you will be able to safely drive without ruining the engine untill you get it figured out


Sorry I did not mean to sound harsh I didn't read your whole post I am used to people saying to just wire them to a switch and leaving them.


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## supernissannx (Mar 1, 2005)

hmm... ok. I'll be sure to check the fan switch. I knew for sure that I had 2 coolant sensors that are just bellow the throttle body located close to each other. One is red and the other black i think. The fan switch.. i thought that was the relay... Any ways if someone could tell me exactly where Ga16de holds the fan switch I would really appreciate it. Thank you.


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## SergioCR (Sep 18, 2002)

supernissannx said:


> I posted one thread on this earlier, so here is an update for today.
> 
> I have a 93 Nissan NX 1600 5-spd. My problem is the fans. They wouldn't go on, causing me to overheat. As of right now, i'm running the fans straight from the battery. So far I have checked both of the fan motors, and the relay. Both seem ok to me. I'm unfamiliar with the temp. sensor (never dealt with it before). Could someone please tell me where it is located? Also if you have had such a problem before, what was your solution? And also how do I check the relay and or the harness it goes onto? I tried shortcurcuiting the harness on where the relay goes onto, but nothing happened... did I do it wrong? It is summer, and hot engine is not a good idea. Thank you


...as the Haynes manual says... "The engine cooling fan is controlled by a temperature switch which is mounted on the radiator (at bottom, driver's side) on 1982 through 1988, or on the thermostat housing on 1989 and 1990 models. When the coolant reaches a predetermined temperature, the switch closes, completing the circuit to ground.
On 1991 and later models, the engine cooling fan is controlled by the ECCS control module, using the coolant temperature sensor"

"The sending unit has a single wire terminal and is located at the end of the cylinder head under the distributor or screwed into the intake manifold on the right (passenger's) side of the engine (GA16)"

I know this is not very descriptive but gives you an idea how does it looks like... if you short the wire plugged into the sensor to ground (chassis) the fan should start working if all relays and fuses are ok...


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## supernissannx (Mar 1, 2005)

under distributor... makes it drivers side, right? I'll be sure to short circuit if i find something there. I did short curcuit the sensor with the red plug/harness, and the rpm went up a bit when i did that. Probably started dumping more fuel... but the fans stayed dead. I will have to test all the wiring that goes between the relay box and the fans themselves. Fun, fun, fun


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## SergioCR (Sep 18, 2002)

supernissannx said:


> under distributor... makes it drivers side, right? I'll be sure to short circuit if i find something there. I did short curcuit the sensor with the red plug/harness, and the rpm went up a bit when i did that. Probably started dumping more fuel... but the fans stayed dead. I will have to test all the wiring that goes between the relay box and the fans themselves. Fun, fun, fun


Take a good look, yes, it's driver side... i have a GA16DE also on my Sentra, i'll take a look and see if i can find the unit... i'll let you know... it is located in the radiator on older models, it's about 1.75cm in diameter bolted to the radiator with one or two wires going out but new models i don't know, manual says it's only one wire going out... i'll go take a look.


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## supernissannx (Mar 1, 2005)

Just to let you know guys. That my fans do not go on when A/C is switched on. So far I couldn't locate the fan switch. Maybe relay plays the role?


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## Twiz (Aug 24, 2004)

There's no thermoswitch in the radiator. You could look here . You have a cooling problem:

Most likely there's air trapped in the cooling system and the watertemp sensor will never set off your fans since the sensor or the thermostat are not completely submersed in coolant therefore it cannot take a proper reading. I've never seen a bad relay... stop tracing wires this is not an electrical problem.


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## SergioCR (Sep 18, 2002)

Twiz said:


> There's no thermoswitch in the radiator. You could look here . You have a cooling problem:
> 
> Most likely there's air trapped in the cooling system and the watertemp sensor will never set off your fans since the sensor or the thermostat are not completely submersed in coolant therefore it cannot take a proper reading. I've never seen a bad relay... stop tracing wires this is not an electrical problem.


"it is located in the radiator on OLDER models" not on 1991 and newer. 

The "air trapped theory" sounds ok if there's LOT of air inside... but for that there should be plenty of space left on radiator to fill with water... also, since the fans are not working when the A/C is enabled i would go for damaged, loose relay or thermoswitch... i have seen a couple of dead relays, one in a Toyota Tercel (EFI Relay) which we all know kills the car since there should be no fuel injection going with that one damaged and one in a Geo Metro, A/C Related... the engine fan goes on but not the A/C Fan, overheating the entire A/C system.


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## Twiz (Aug 24, 2004)

The low pressure switch will never let any A/C components start... your cooling fans will not start. But that's totally separate from the cooling operation. You don't have to fix your A/C so your cooling fans work.


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## gtlaw (Jun 24, 2005)

not to worry you, but i had this problem with an old integra and why all my replies say to check the cooling system not electrical components. the air can come from a leaking head gasket and when this happens the fans stop working


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## mille-16i (Jun 16, 2004)

the way to get the sir out is to take off your rad cap and run the car at idle till it reaches full operating temp then add water this will expell the air out of all the nooks and crannys also have the heater to hot.

However I think the problem is electrical not mechanical the fans should come on with ac switch on even if the ac compressor dose not kick in. I would chase down the wires and relays and fuses I know that is not a fun job but that is probably where your problem is my guess a bad relay.


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## Twiz (Aug 24, 2004)

gtlaw said:


> not to worry you, but i had this problem with an old integra and why all my replies say to check the cooling system not electrical components. the air can come from a leaking head gasket and when this happens the fans stop working


I agree... the head gasket will get shot from overheating... specially if he advanced the timing.


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## supernissannx (Mar 1, 2005)

The compressor does kick in (sorry didn't mention). So you're saying that I have air in my cooling system? Then I must have a lot of it to cause this problem... Yes I'm leaking a bit of oil, but I will try to run the air out of the system. Ok what is the procedure again? I haven't done this type of thing before. And what about the relieve pressure bolt on the thermostat? Tell me how I do the whole procedure again? BTW, there is only one relay for GA16DE that goes for the fans, is that right? Thank you.


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## Fonque (May 1, 2002)

Unplug your CTS, then start the car. The ECU will turn on the fans automatically if it cannot get a signal from the CTS.

If your fans do not turn on from this you have an electrical issue. Also the other test I think you already did is turn on the A/C. When the A/C is switched on the ECU should turn the fans on.

If both of the above tests fail then you need to trace the problem back from the ECU. this is NOT an air in the system problem. The above 2 tests, if failed eliminate that possibility.

Check fuses in dash, check engine/fan relays, replace CTS and thermostat for good measure, bleed system. If everything fails then swap the ECU with a known good one, and try the above 2 tests again after every step you complete.

I have the FSM at home and I can scan pictures of the trouble shoot process for this if you like?


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## supernissannx (Mar 1, 2005)

I would love to get my hands on that! what is CTS? Haven't dealt with that yet.


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## SergioCR (Sep 18, 2002)

supernissannx said:


> I would love to get my hands on that! what is CTS? Haven't dealt with that yet.


I have posted the FSM on .pdf format... get it here:

http://www.nissanforums.com/showthread.php?t=97788


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## supernissannx (Mar 1, 2005)

It's funny, because such a simple thing and nobody knows where it's at...
I called the dealership, and they tell me there is only two sensors, yes two. One for the ecu, and one for the dash. Now... the one that's for the ecu actually is the one... ECU sends the the voltage to the relay which switches them on. This is how it works on B13 platform. And nobody knew... Now I gotta run everything starting from this sensor to the ecu, and then from the ecu to the relay and then from the relay to the fans. I have a feeling that's it eather the ecu itself or the sensor, it's rare the the wiring this thick gets burned at only 12V.


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## supernissannx (Mar 1, 2005)

ok the progress so far... I tried and curcuit the the relay harness that leads to the fans, and both of the fans come on. Now the upper two nests I wouldn't try to curcuit, because that's where the relay gets the voltage, correct? Now what i need to do is to test those two upper nests with the ohm meter, does that sound right to you? Give any suggestions anyone.


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## gtlaw (Jun 24, 2005)

> I tried and curcuit the the relay harness that leads to the fans, and both of the fans come on


did you test the relay


> Now what i need to do is to test those two upper nests with the ohm meter


you mean check for continuity between ecu and and relay socket or voltage coming from the ecu? 
if you have voltage coming from the ecu then the relay is bad 
don't get confused with the voltage from the battery that should always be present make sure when you check the car is hot and the key is in the on position if not running


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## supernissannx (Mar 1, 2005)

yeah i'll do that. I might take it to the dealer to run my codes. The guy said it wouldn't cost me anything, so might as well do that.


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## supernissannx (Mar 1, 2005)

i doubt that i have voltage coming from the ecu though... In that case, it could be either the wiring, the sensor or the ecu itself that's causing the problem. Correct?


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## supernissannx (Mar 1, 2005)

I have the FSM at home and I can scan pictures of the trouble shoot process for this if you like?[/QUOTE]

Yes please!!!


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## SergioCR (Sep 18, 2002)

supernissannx said:


> It's funny, because such a simple thing and nobody knows where it's at...
> I called the dealership, and they tell me there is only two sensors, yes two. One for the ecu, and one for the dash. Now... the one that's for the ecu actually is the one... ECU sends the the voltage to the relay which switches them on. This is how it works on B13 platform. And nobody knew... Now I gotta run everything starting from this sensor to the ecu, and then from the ecu to the relay and then from the relay to the fans. I have a feeling that's it eather the ecu itself or the sensor, it's rare the the wiring this thick gets burned at only 12V.


....do they actually told you where the sensors are located? i have seen dead temp. sensors on several cars, they just stuck short (fan always on) or open... (never starts fans again) if that's the problem just change it for a new one, make sure the temp range is the same.


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## Twiz (Aug 24, 2004)

supernissannx said:


> It's funny, because such a simple thing and nobody knows where it's at...


Good luck!


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## payk (May 5, 2004)

i know this is old but fyi for future searchers..it could be a short in the trunk check your wires back there.. there is a bunch of them that can short out and turn off the fans...i know coz i paid the dealr 120 to find this out after bringing it in 3 times


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