packerfan

Anybody know if it's normal for only one fan of dual fans to run, I think I might have one fan dead. it seems to run hot when stuck in traffic jam or idling for a time.
any way to test fans?

highhat

have you checked to see if both fans are on when its hot?
try turning on the ac then check if both fans come on. normaly only one fan is on untill it reaches a certain temp then the sec fan comes on i forget the temp ranges for the fans.

IROCNParts

put in a 180 thermostat and a 195 cool fan switch and the car will run cooler, not to mention save itself on the lifespan

3.1EyeCandy

iTrader: (3)

As far as saving itself, the cooler temps are better for internals. But remember...the hotter your car runs, the more efficient it is at burning the fuel (to a point). This is the reason why when you run a cooler thermostat on a computer controlled car you get less MPG. This being on the account that the FUEL enrichment mode is engaged to heat up your engine to normal opperating temps...burning more fuel.

Lesson here: When you run a cooler thermostat or put a fan switch on, it's best to go ahead and get a chip that stops the fuel enrichment mode earlier in the temperature band of the engine.

MikeS

Packerfan,

What year is your car. There seems to be a little disagreement over exactly how the passenger side fan works. The conclusion that I have reached from my research and experimentation with my '87 is that the passenger side fan will only run when the temperature is very hot (234 degrees i think). It is run only off of the temperature sensitive fan switch located in the passenger side cylinder head. Turning on the AC will not make this fan run. However, turning on the AC (or unplugging the connector on the refrig. line pressure switch) will make the driver's side fan run no matter what the temperature is. If your passenger side fan never comes on, there are three likely reasons:

1. Bad temp switch in the cyl head
I have checked them with a multimeter and heat source before, but if you go through the trouble of removing the stock one, you might as well replace with a slightly cooler one for about $35.

2. Bad relay
Located on the passenger side by the radiator cap and headlights. You should be able to find it up there (there are two - one for each fan)

3. Car never gets hot enough to turn the second fan on. Remember, the second fan is not supposed to turn on until the car is over 230 degrees. If it doesn't get that hot, it won't turn on.

There are lots of things you can do to test the fan circuits. For right now, I recommend finding the wire that connects to the switch in the passenger side cylinder head. You can find it by crawling under your car and looking in between the back two cylinders on the passenger side. Squeeze the connector and remove it from the switch. Use a nail or something to ground the wire that you just pulled loose and see if the fan runs. If it does, your culprit is the fan switch. Order up a Grand National switch if you want a colder one (Borg Warner P/N TFS8 (208* IIRC)), or just get the stock replacement part (P/N TFS1).


I'll be swapping to the Grand National switch any day now since my old one is shot and it is getting quite warm down here. The only problem that I can see with that switch is that it will make the passenger side fan turn on before the driver's side fan (which turns on at 225* I believe), in effect making it the primary fan. Not how the system is supposed to work, but I see no reason not to do it.

Ok, I've written a lot now. Let us know how it goes.

MikeS

p.s. 3.1EyeCandy mentioned some PROM stuff. That's another thing. The temp that the driver's side fan runs at is programmed in the PROM and can be altered by running a custom PROM. This could save the trouble of switching to a cooler secondary fan switch, and not reverse the roles of the fans.

Hung Start67

Hey bro..going thru cooling 101 myself here...i have a 92 z..not sure if yours is different thou...im losing it here but one fan is controled by the chip and the the other is controlled by the fan switch in the cylinder head...i bought a fan switch from hyper tech..and also a thermo master chip..so the other fan turns on much sooner...also had to run 160 deg stat because of the chip...then had system flushed and wow no overheating....good luck bro