V6camaroman

ok guys my car is an 85 z28 with the 305tpi (in sig). the person before me kept screwing witht he fan and now it wont work at all. the wires are all cobbed up. im sick of trying to tear apart wires and figure out whats wrong with it. how hard would it be to put a mecanical fan set up on my car? my dad owns a junk yard so i have all the parts i need. all i need to know is can it be done and what do i need to do to complete this job. has anyone done something similar to what i want to do?

Insomniac92z28

The problem with going to an mechanical fan is that the water pump runs backwards on these cars (mine does you may want to look at yours), since it is driven off of the backside of the belt, and the fan will run backwards too. I would suggest getting an aftermarket fan control and installing it with your current fan.

Charlie

92BLKL98

The 92 drives CCW (serpentine drive) the 85 has V belt drive which drives CW. An engine driven fan will cost you horsepower and much needed clearance will be lost. You will need to fabricate some kind of fan shroud to optimize cooling (a sore spot on 3rd gens). I would get a good schematic and fix the electric fan circuitry. You and your car will be happier. In this case it's hard to improve on the original design and a mechanical fan is a step in reverse.

MrDude_1

later model trucks had a surp belt, but still had mechanical fans... so you have a chance of finding a mechanical fan of the correct rotation.

early 3rdgens had mechanical fans, so you could get a fan shroud from one of them. (needed)


even then... you will have cooling problems in traffic.... the mechanical fans could bearly keep the low low low powered early cars cool.. i mean, at idle, the fan isnt turning much... not alot of air is pulled thru, and theres no air movement... temp rises FAST.
you may actually have to rev the car to keep it from overheating.. lol ( i know that from experiance)


instead... think about this. the fan only needs two wires. a positive power wire, and a ground wire.

if you arnt good at electronics, i can understand you wanting help, but its not that complicated. even if you have to totally re-wire it.

V6camaroman

ok after reading this i have decided to keep my electric fan. mrdude_1 ive got a ques. ok here goes. my car has the stock electric fan in it. there is the stock plug going into the fan and two wires come out of it. ok if i fallow the one it goes straight to the front of the radiator support. so i know that ones the ground. ok the other one goes up and along the firewall of the car and through the firewall to the fuse panel. and that wire has a connector on it thats stuck in one of the holes in the fuse box. and my cars fan still wont come on? whats wrong with it.

V6camaroman

common guys someone has to know

razor

Have you verified that your fan motor is not fried??? Try hooking a direct power source to the terminals and see if the fan spins. Then verify that you have voltage on the supply wire from the fuse panel. Is this wire original or has someone modified it??? Try doing a search on here to find the wiring schematic for your car to verify that the wiring is corect. Just because its plugged into your fusebox doesn't mean its correct. Also what about your temp sending unit that controls fan operation??? Is it hooked up and good to go??? If the wiring is over your head why not run the fan on a toggle switch??? Its kinda cheesy and I don't think I could handle it myself but lots of people have done it.

8Mike9

Seems like it's been monkey rigged to work, at some point in time.

I'd suggest a Chiltons or Haynes to get ya going.


Or bypass the whole sha-bang and set it up with a new relay-control.

DENN_SHAH

iTrader: (1)

V6camaroman, i can get you a wiring diagram if you need it.

V6camaroman

ok what do i need to do to run it off from a switch?

DENN_SHAH

iTrader: (1)

you need a switch, a relay, some terminals, some good wire, a section of fuseable link or a fuse holder & a good fan.

Snake Oiler

Did you check the thermal fan switch(TFS)0n the passenger side head?If the wiring is to messed up, you could run the relay setup mentioned above with the ground wire going to the fan switch.When the switch gets to a certian temp (220* or so) the switch closes and turns the fan on.

MrDude_1

whoa..

thats like saying, please, burn down my car.

the fan draws way too much power to try to run from the fuse box.


if you dont mind always having them on when the key is on, heres the simple way:

MrDude_1

before you do this, try this test.

take the main power wire for the fan, the positive one that you currently have going to the fuse box, and touch it to the batterys positive terminal... if the wire is thinner then 12 gauge, it may get hot quick... just so you know. the fan pulls alot of power.

if the fan comes on... great... wire it like posted above.


if the fan stays off, then try cleaning off the ground connection. possibly running a new wire off it. then try again.

if the wire is really thin, or is speaker wire or some other small, non automotive wire, it just might not be able to give the fan the current needed to get it spinning. so you may have to upgrade the wire if thats the case... it really sounds like the previous owner didnt know what he was doing, so i dont know what it looks like.

if it still doesnt come on... you need a new fan motor first.


btw, since you have junk yard access, you can get a new OEM relay for $6 (if you want to look stock) and then salvage the connector from another GM car

dyeager535

I've been dealing with the fans a lot lately, so I hope I can help with this.

Fan wiring (basically) is extremely simple in principle and operation.

Keep in mind I was dealing with dual fan setups, so there may be some slight differences, but I'll try to keep it as simple as possible.

The fan is going to have a relay hooked up to it. The two wires going to the fan are obvious, you found the ground, the other is the 12V lead. the 12V lead will go to one terminal on the relay.

There will be a total of 4 wires on the relay connector. One large wire will have constant 12V directly from the battery. The other large wire will be the one to your fan.

Now you will have two small wires on that connector as well. Assuming your '85 is like my '88 dual fan setup, one of the two small wires will go to the ECM. The ECM GROUNDS that circuit. The other wire will be 12V, in my case it is 12V fused, and is hot only when the key is on. (so the fan will only work when the key is in run/start, and apparently only when the engine is running)

Since I don't know your skill level, this is how the relay works. I'm no electrical pro, so my terms might be wrong, but the operation is this: when the key is on, there is power going into the relay on one of the small wires. (the fused one) However, when the ECM doesn't ground that circuit, (when engine is cold) nothing happens. When the ECM commands fan operation, it grounds that small wire.

When that circuit is completed, because the fused 12V is grounded through ECM, it "switches" the relay, and allows the large 12V battery wire to "contact" the wire running to the fan. Since the fan is already grounded, it runs.

Does that make sense?

Now on my setup there is also an AC pressure switch, but I'm not running it.

I'm not advocating this, because I'm not sure what the ECM may do, but if you disconnect the coolant temp sensor from the head, while the vehicle is running, and jump the two terminals, the ECM will think the engine is extremely hot, and will trigger the fan.

But again, this is a very simple circuit, just tracing the wires is difficult, especially if you believe someone has cut them up, as you then need to trace their entirety.

V6camaroman

ok guys thanks for all your help and info. i ended up running the fan direct on a switch. it runs good now and i can turn it on or off at any time. its not the most beneficial set up but it woorks for me. and i didnt cobb it all up wither it was installed correctly.

MrDude_1

thats not safe. most likely, that switch cannot take the AMP draw the fan puts on it... it will eventually heat up and fail.

DENN_SHAH

iTrader: (1)

or worse yet, go up in flames.

V6camaroman, did you put a fuse of some kind at where you are getting power for it from?

V6camaroman

i have not thought about that mrdude. its a pretty small switch too. will a bigger toggle switch be more efficient for me?

Insomniac92z28

just use the stock fan relay and the switch you have. You will need a relay for it to be safe, and you have the stock one. So why not use it.

MrDude_1

you NEED a relay. even if its a free junkyard relay.

if you didnt need one, i wouldnt have put one in the simple fan circuit... and the factory wouldnt have used one... remember $2 a car saved for them = $20,000 saved for them a year.... but you NEED one.


the only switches that can handle that current load would be so large it would look stupid in your car.