# Relays, Radiator switch and sensor help?



## stanza86 (Jun 6, 2005)

1987 Nissan Stanza GXE Automatic

This is what I need help with:
1 - Which "Radiator Fan Switch" on the radiator(upper or lower) do I replace the new with?
2 - What is the relay switch diagram in the engine compartment on the passenger side.
3 - Also, how can you tell if a relay switch has gone bad since it is encased inside a seal cap.
4 - See PS at bottom

Long story short - 
My fans are not working properly. I discovered this when I developed a small leak in radiator and realized that my fans were not coming on. I spent all day researching why they were not coming on and found that the problem was the "radiator fan switch" after some website suggested that turning on the a/c would make the fans run then it was the radiator fan switch. 

So I ordered one but mine has an "upper" and "lower". I don't know which one to replace. The salesperson at AutoZone suggested I refill the radiator, turn on the a/c and see how long the fans would run. 

So I placed some radiator sealer in radiator, refilled the radiator with water only(since I have to replace the switch when it comes in), started the car up and drove it around the block a few times.

Well now the fans are coming on but only when the temperature gauage gets to the H mark. When I turn on the a/c, I hear the compressor kick in, then I hear a relay switch click and then the fans turn off. The fans do not turn back on at all until I turn the a/c off and then they come back on. Repeated this several times and everytime the same thing happens.

I believe it is the "a/c relay switch" but my engine compartment relay bracket has no cover to let me know which relay is which so I don't know which one is the a/c relay or radiator fan relay.

PS..There is a sensor(about 3" in height) located on the exhaust manifold where it creates a Y. The sensor has a wire(I believe green) built into it that is also about 3" long with a female connector. The location would be like this: Front of car; radiator; radiator fan; then the sensor directly in the center of the "Y" on the exhaust manifold below the spark plug wires. 

What is that sensor? I kindda pull the wire out by accident while unplugging and replugging connections to ensure proper connections. The car still runs.


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## 88Multi (Jun 9, 2005)

*re: 87 Stanza*

This is what I need help with:
1 - Which "Radiator Fan Switch" on the radiator(upper or lower) do I replace the new with?
Since I have a 5 speed Multi I appear to only have one sensor on the rad. However, a quick test to see which is failing, is - unplug the connector from the sensor, and using a test wire (paper clip) short the two wires in the harness. This tells the computer or relay that temp is reached and to turn fans on. If you get the right one - you found it. Don't leave the wire connected for very long, though, because the if the second is the computer temp sender it may damage the computer. If neither turn on the fans, the relay has failed.

2 - What is the relay switch diagram in the engine compartment on the passenger side.
Don't know - The multi has its relay on the drivers side. The one closest to the front and closest to the battery is the Rad fan relay Its black. Starter relay is blue, and A/T Inhibitor relay is Gray. 
On the passenger side - the two AC relays are closest to the back, the AC compressor relay is on the outside, and the AC Fan relay is on the inside.

3 - Also, how can you tell if a relay switch has gone bad since it is encased inside a seal cap. 
Electrical testing only - no visual tests are reliable

4 - See PS at bottom
This is your Oxygen Sensor - If you've pulled out the wire, you are not running correcty (and possibly this is the overheating problem!) Repair or Replace as soon as possible!

Good luck
Wayne


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