spiderman

i have a 1987 stanza that the radiator fans will not come on in. I jumped the connection at the harness where the sensor from the radiator plugs in and the fans came on. So, I replaced the sensor in the radiator(mine only has a lower one) and the radiator fans still do not come on. I am almost 100% positive that all of the relays are good. I even went as far as replacing them all with " new to me" relays which netted me no positive outcome. When I turn on the a/c the radiator fans come on. Can anyone tell me what I am not doing correctly? Or, what it is that I am not checking that I should be? Am I missing a sensor or something?
The hottest it has gotten is just over the halfway mark on the gauge. I am very concerned as I truly love my nissans and want them to run correctly.

bikeman

Maybe it's just not getting hot enough to trigger the fan, half way on the gauge is not warm enough. I believe only the large one comes on, the smaller one kicks in when the A/C is on. Start it up, block the wheels and place it into drive, this will warm it up quicker. Watch the gauge, I'd say it has to climb to at least 2/3 up to 3/4 for the fan to kick in. If it was overheating the gauge will be much higher than the half way mark. How old is the thermostat, maybe it's weak and opening too early or stuck open, is your heat good?

PapaCap

On my 90 Stanza, I was having the same problems. I did the same checks, except the sensor in the radiator because the 90 doesn't have one. But anyway, I changed the temperature sending unit (not the coolant temp sensor) and low and behold, the fans began to work. But like Bikeman says, they come on when it gets really hot. I read somewhere in the 200+ degree range (Chevy's come on at 220, which I friggin' hate). Even without watching your temp gauge (which may be faulty in a 20 year old car), if your radiator begins to smoke, it's overheating and the fans should be running. If not, it's probably a sensor.

pc

spiderman

I am not real sure that it is getting hot enough for the fan to come on. I just changed the thermostat out on the car a few days ago but the fanss heave yet to come on on their own. The heat is working fine in my opinion. But, the man I got it from had said that his daughter and he both thought that the heat wasn't working up to par. He also said that the a/c wasn't working either but it also seems to be working fine.
I wonder if the 1987 model has a temperature sending unit in the radiator and in the intake near the coolant temperature. There are two sensors in the intake near where I put the new thermostat. One is a single wire and the other is a double wired sensor (it looks like one anyway) to the passenger side of the single wired sensor. Both are in the intake in what appears to be a coolant flow area.
Any clues as to what the two are and which one of those two is what?
Thanks for the feed back.

bikeman

I'm pretty sure the only thing that triggers the fan is the sensor at the bottom of rad, the other are for temp gauge. As I said the fan (large one) comes on when the temp gauge is about 2/3 - 3/4 up, they both come on when the A/C is on, I don't think it's getting hot enough to activate the fan.

spiderman

Thanks for the input on this one guys. I will take her on a long drive and let you know the results of said drive.

Spiderman