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Greetings all -

Just polling the masses to see if anyone has come across this issue before. My 93 SE (188k mi) was having some cooling issues recently. On highway speeds the temps were in the middle, but as soon as I hit traffic the temps would slowly rise. The other day the needle got near the "H" and boiled coolant over into the overfill tank because it was idling in the driveway. After some research I narrowed the issue down to either the thermostat or a radiator issue. Of course, no leaks were going on anywhere so I thought it might be the thermostat. The waterpump is about 2 years new. I changed the thermostat out yesterday (real PITA) - still the same issue. Of course, this time while hovering over the engine bay I noticed the fans never kicked on and a lightbulb instantly went off in my head. Oddly, if I shook the radiator around the driver's side fan would rotate - notice I didn't say "run", but rotate. Once I quit shaking it or tapping on the fan guard, the fan would simply quit rotating. It's almost as if either the fan motor is dying/dead or there is not enough voltage being supplied. The passenger side fan never turned at all. I checked and reseated both the relays and fan connectors. If I were to check voltages, would I simply touch the nodes of a voltmeter on the fan connector ends? Would the Haynes suggest a point to check voltages?

Given the above scenario, what would be your thoughts on what's causing the issue? A: bad fan motors, B: bad relays, C: bad connection or low voltage, D: OTHER

Thank you in advance for any suggestions you might have.
 

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2018 Nissan Pathfinder SL
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You will find that there are not built in test points, so if you are serious about checking the voltage you can split the wire and probe the conductors, be careful not to cut them.
you can use any ground, so just open the 12v supply, with the FAN on, ie under load.
Yes just touch the conductor and measure the voltage, should be close to 13 - 14 V with the engine running
Then wrap with electrical tape. It helps if you do this where it can be covered with the harness.
However, my first suspect is the fans, these are mechanical and at 188k I am not surprised they are dieing.
 

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Discussion Starter #3
I appreciate the suggestions for checking voltages. My only curiosity is how both fans quit working. Don't they have independent motors? How could both completely go out?
 

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On my manual 97 both fans turn on when cold with the A/c ( cold is a relative term on a 104 degree day in Dallas) and off when i turn the A/C off.
So i suggest you turn the A/C on and unplug the fans and probe the connector.
use a grnd on the chassis, and you should find 12V on at least one pin. if not check the relay, and last is the ECU see EC-430
 

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Discussion Starter #5
On my manual 97 both fans turn on when cold with the A/c ( cold is a relative term on a 104 degree day in Dallas) and off when i turn the A/C off.
So i suggest you turn the A/C on and unplug the fans and probe the connector.
use a grnd on the chassis, and you should find 12V on at least one pin. if not check the relay, and last is the ECU see EC-430
Thanks again for the suggestions. I'm going to pick up this project again either tomorrow evening (Mon) or on Tuesday when I'm off. The thermostat was a cheap fix and I didn't mind replacing it. I just hope the fans are truly the cause because if I replace those and they still don't turn on I'll be pissed. I'll more than likely check for voltages at the connectors. As for the relay, is there a good way to check this? Does EC-430 refer to the wire coming off of the ECU?
 

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yes shows the schmatic. I found it difficult to find much in the FSM. Page number may varry if you have dffernt year FSM.
dont forget you can buy replacement fans from the wreacker yards or a generic from places like autozone as well as the specific fit ones.
 

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Discussion Starter #7
I just wanted to post a quick follow up for anyone experiencing this same issue.

To finalize troubleshooting, I swapped the A/C compressor and fan relays (they are the same). The A/C continued to work so I knew the relay was good. I checked the fuse box between the fender and battery and the fuse was good. The only component remaining was a faulty cable between the relax/fuse box and the actual fan connector itself. At that point I had decided replacing a 188k mi fan wouldn't be a terrible idea regardless. As soon as I replaced the fan assembly (no choice with an auto parts store - all they sell is a generic), the fan started up nicely. I'm only running with one fan right now, but no more overheat issues and my A/C all of a sudden feels much colder than ever. It makes me wonder how long I had a weak fan in the engine bay.

If anyone as a spare fan motor laying around, I'll need one for the passenger side fan. Thanks all for your help.
 

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I just wanted to post a quick follow up for anyone experiencing this same issue.

To finalize troubleshooting, I swapped the A/C compressor and fan relays (they are the same). The A/C continued to work so I knew the relay was good. I checked the fuse box between the fender and battery and the fuse was good. The only component remaining was a faulty cable between the relax/fuse box and the actual fan connector itself. At that point I had decided replacing a 188k mi fan wouldn't be a terrible idea regardless. As soon as I replaced the fan assembly (no choice with an auto parts store - all they sell is a generic), the fan started up nicely. I'm only running with one fan right now, but no more overheat issues and my A/C all of a sudden feels much colder than ever. It makes me wonder how long I had a weak fan in the engine bay.

If anyone as a spare fan motor laying around, I'll need one for the passenger side fan. Thanks all for your help.
I have exactly the same problem with my 93 sentra. The deal is, though, that the cooling system was working just fine until i lost an engine seal and fried the crank on the old motor. I replaced the motor with another (used) one and used every single sensor, plug wiring harness, etc. and the engine started right up with the exception of the overheating problem. I removed the thermostat - it still runs in the half way point and now the fans have stopped working unless you turn on the air conditioner! I am looking for a way to wire around the auto function of the fans and just leave them on every time the key is turned on. The only pause I have with that is that maybe the fuel will continue to flow at "cool" settings. I simply cannot believe that both fans decided to go out at the same time due to age - and they DO run when the a/c is on. What the heck is going on with this system?
 

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Strip the motor and check the spring loaded armature brushes.

Although spring loaded, if they reach their lifespan, they dont contact the commutator, and will cause exactly what you experienced.
If you knock it about they sort of contact.

Costs next to nothing to replace!
 

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Greetings all -

Just polling the masses to see if anyone has come across this issue before. My 93 SE (188k mi) was having some cooling issues recently. On highway speeds the temps were in the middle, but as soon as I hit traffic the temps would slowly rise. The other day the needle got near the "H" and boiled coolant over into the overfill tank because it was idling in the driveway. After some research I narrowed the issue down to either the thermostat or a radiator issue. Of course, no leaks were going on anywhere so I thought it might be the thermostat. The waterpump is about 2 years new. I changed the thermostat out yesterday (real PITA) - still the same issue. Of course, this time while hovering over the engine bay I noticed the fans never kicked on and a lightbulb instantly went off in my head. Oddly, if I shook the radiator around the driver's side fan would rotate - notice I didn't say "run", but rotate. Once I quit shaking it or tapping on the fan guard, the fan would simply quit rotating. It's almost as if either the fan motor is dying/dead or there is not enough voltage being supplied. The passenger side fan never turned at all. I checked and reseated both the relays and fan connectors. If I were to check voltages, would I simply touch the nodes of a voltmeter on the fan connector ends? Would the Haynes suggest a point to check voltages?

Given the above scenario, what would be your thoughts on what's causing the issue? A: bad fan motors, B: bad relays, C: bad connection or low voltage, D: OTHER


Thank you in advance for any suggestions you might have.
Hi I have the same problem the gentle man working on my car used 2 wires to put my fan on constantly when my ignition is on but in doing so he I think burned out the little piece that the relay plug into so how would you change the whole relay box
 

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