2.3 daily driver, fan won't come on??

Stangler · Apr 16, 2007

How is the stock 4cyl fan controlled in 88' 2.3 stang? I just got done replacing the engine, and I've double checked everything, but the fan is not working.

Does it get a signal from the computer, or is one of my sensors bad? I made sure I connected all the wires(looks like there are two of them for water temp besides the computer sensor)? I'm good with 5.0's, but never looked into the 2.3 systems. What's up???

Nate

kevinspann · Apr 16, 2007

Are you sure its hot enough for the fan to come on? It takes quite awhile, i think it comes on at around 180-190 degrees

snake109 · Apr 16, 2007

mine hardly ever comes on, and i live in the houston heat

Red_LX · Apr 16, 2007

kevinspann said:
Are you sure its hot enough for the fan to come on? It takes quite awhile, i think it comes on at around 180-190 degrees

ha...try 240-250 degrees. It comes on about 20 degrees before what is considered overheating. Stupid design, because if it turns out the fan doesn't work...you're screwed (yeah, happened to me)

Jimmy2Times · Apr 17, 2007

I'm dealing with this same problem in my '87 2.3. Here's what I've found so far in my investigation:

The fan is controlled by a module that's under the dash on the far left side (pretty much right below the driver's side A-pillar). The module has 8 wires going into/out of it. It gets power from the starter solenoid. It gets input signals from the EEC-IV, the temp sending unit mounted on the bottom of the intake, and the A/C if the vehicle is so equiped. And of course it has a ground and an output wire to the fan motor.

Red_LX, does it really not come on until it gets that hot? In testing mine I let the engine idle until it got 3/4 of the way up the stock gauge and the fan never came on. Should the fan have come on by that point?

Assuming mine is in fact bad, I tested the voltage of each of the 8 wires under various conditions, and I've determined the problem with mine is either a bad temp sending unit or the fan control module itself. I'm planning on replacing the temp sending unit sometime this week and trying it again. I'll keep everyone here posted on what I find out.

Red_LX · Apr 17, 2007

Yes. The factory gauge has to be in the RED before the fan will kick on, i.e. all the way at the top of the gauge at "H."

I've read that most newer cars are designed like that because the hotter a car runs, the lower its emissions are. So they make it so the fan doesn't kick on until the car is nearly overheating.

I think it's dumb...on my '90 2.3 Mustang I got stuck in traffic and the temp went up and up...finally it reached where the fan should have kicked on, except it didn't (fan was apparently dead) and my car overheated shortly afterward and cracked the head.

ethangsmith · Apr 17, 2007

I've found a real quick test to check what is wrong: With the engine at temperature and the engine running, turn the A/C on. This will test the A/C circuit, fan motor, and fan relay. If it turns on, all of that is in working order. Next step is to disconnect the 1 wire coming off the fan switch. It should be threaded into the bottom of the intake (87-93 cars) or the heater core inlet pipe (79-86 cars). With the ignition on or car still running, ground that connector. Use a small nail and insert it into the connector and touch it to the engine block in close proximity to where the switch is threaded in to the intake. This will check the connector, ground, and fan switch harness. If the fan turns on, suspect the switch. If it does not turn on when the connector is grounded, check your harness, fan relay, engine/intake ground (or heater core pipe ground on earlier cars), or fan.

Jimmy2Times · Apr 17, 2007

ethangsmith said:
With the ignition on or car still running, ground that connector. Use a small nail and insert it into the connector and touch it to the engine block in close proximity to where the switch is threaded in to the intake. This will check the connector, ground, and fan switch harness. If the fan turns on, suspect the switch. If it does not turn on when the connector is grounded, check your harness, fan relay, engine/intake ground (or heater core pipe ground on earlier cars), or fan.

I read about the same test on another site tonight, tried it, and sure enough the fan came on. Tomorrow I'm replacing the switch. I've got the stock temp gauge sending unit from my '90 GT and it looks like the same piece... anybody know if I can use it and save a few bucks?

Jimmy2Times · Apr 17, 2007

Red_LX said:
Yes. The factory gauge has to be in the RED before the fan will kick on, i.e. all the way at the top of the gauge at "H."

I've read that most newer cars are designed like that because the hotter a car runs, the lower its emissions are. So they make it so the fan doesn't kick on until the car is nearly overheating.

I think it's dumb...on my '90 2.3 Mustang I got stuck in traffic and the temp went up and up...finally it reached where the fan should have kicked on, except it didn't (fan was apparently dead) and my car overheated shortly afterward and cracked the head.

Man, that really sucks. I agree that's a stupid design... if mine acts that way I might wire up a manual switch so I can just turn it on from inside the car.

pimpstang18 · Apr 17, 2007

i just wired mine up so it comes on with the ignition, car runs much cooler and the ac blows colder because of the air moving over the condenser. seems to be working fine so far

86crazyhorse · Apr 17, 2007

hey nate. whats up my SVO does the same thing.i replaced the fan controle mod when mine wouldnt turn off.then it wouldnt turn on after i swapped it out unless i had the A/C on.good luck with the turbo stang.

Red_LX · Apr 18, 2007

pimpstang18 said:
i just wired mine up so it comes on with the ignition, car runs much cooler and the ac blows colder because of the air moving over the condenser. seems to be working fine so far

Having your fan running all the time isn't really a good idea.

ethangsmith · Apr 18, 2007

If the switch has the same dimensions and threads, I would imagine you can use it. I think that's one of those standard parts Ford used for ages. Having your fan running all the time probably isn't the best idea. I would wire a switch up under the dash to control your fan. All you would need to do is splice the fan switch wire running to the intake and then run a wire to a good ground on the other side of the switch. Just flick the switch on and it will ground and turn the fan on.

kevinspann · Apr 18, 2007

my fan seems to come on earlier than 240-250 degrees, ive had the car just sitting running and the fan came on before it got to the top of the Coolant temp gauge....oh well, at least i know it works

Jimmy2Times · Apr 19, 2007

ethangsmith said:
If the switch has the same dimensions and threads, I would imagine you can use it. I think that's one of those standard parts Ford used for ages.

I was thinking the same thing, so I put the GT's temp gauge sending unit in place of the fan switch and tested it. Well, not only did the fan not come on, but I fried the fan control unit! When I pulled it out from under the dash, the terminals for the starter solenoid (12V power source) and fan motor were both scorched. And grounding the fan switch connector to the car body no longer made the fan come on. I don't know enough about electrical stuff to say exactly what happened, but the only logical conclusion is that swapping out the fan switch with an incorrect piece killed the control unit.

I looked up the respective part numbers for the temp gauge sending unit and the fan switch on Advance's website and sure enough, they are two different part numbers even though the parts look the same. So I guess they have two different resistances or something?

At this point I think I could get the fan working if I get a new control unit and the correct fan switch, but looking online those parts are about $55 new for both. I think I'm just gonna wire up a manual switch under the dash for the time being and keep my eye out for a control unit in the junkyard. Anyway, hopefully someone on here will learn from my mistake.

89' RICE COOKER · Apr 19, 2007

everyone i know has just wired up a manual switch. there are a few ways to wire one. mine is simple...one wire from the fan to a switch under my steering wheel ( where the switch is grounded), and the other wire goin to 12v source. i used my ignition so if i accidently forget to turn it off, it goes off with the car. and the it wont run until its grounded. that way i dont have a dead battery or a fried fan. all 5 of my 2.3's ive owed have either never worked or came on around 225 degrees. i usually turn mine on arounf the halfway mark. Ya Pimpstang, having it come on with your ignition is not good. your cars needs to atleast warm up. running it cold like that with do a number on your gas milage and not to mention make your car run like crap being it never gets up to temp to burn off all sorts of thing.

Jimmy2Times · Apr 19, 2007

89' RICE COOKER said:
mine is simple...one wire from the fan to a switch under my steering wheel ( where the switch is grounded), and the other wire goin to 12v source. i used my ignition so if i accidently forget to turn it off, it goes off with the car.

Exactly what I'm planning on doing... get the power from the ignition just in case I forget to switch it off when I turn the car off. From all these replies this seems to be a common problem... either the fan coming on too late or not at all.

I do have one question regarding wiring in a manual switch. I'm going to put a fuse in the circuit and it looks like the factory fuse for the fan is a 15 amp, so that's what I'll use. Should I put the fuse between the ignition power source and the switch, or between the switch and the fan motor, or does it matter? I'm thinking between the power source and the switch, so that way the switch is protected as well.

Red_LX · Apr 19, 2007

Being the eccentric type I am...a simple switch wouldn't do. Nor does hard-wiring.

On my Thunderbird, I have the fans wired into an adjustable temp fan controller (Flexalite, runs about $35). So the fans kick on in the 200-220 degree range. Also, I have this controller run through a relay that's wired into the ignition so the fans can't kick on after the car is shut off.

It's a little complicated and rather a mess of wiring, but it works very well.

Jimmy2Times · Apr 21, 2007

What amperage fuse are you guys using to protect your fan power circuit? My Haynes manual says there is an 18-ga fusible link protecting the power wire from the starter solenoid, but I'm planning on using the wire from the ignition switch to the fan control module as my power source and there is no fuse or fusible link on that one (if I'm reading my wiring diagrams correctly).

I have a single fuse holder I'm going to wire in between the ignition power source and my manual switch, but I don't know what amp fuse to use. Previously I thought it should be a 15-amp from reading my fuse panel sticker, but I re-read it and it says "Cooling Fan/Compressor Clutch Control" which I don't think is the actual fan motor circuit.

ethangsmith · Apr 21, 2007

That may be it. I would just use a 15 amp fuse to start. If it pops, go to a 20 amp. If it still pops, I would check your wiring. I would say a 15 would be fine though.

2.3 daily driver, fan won't come on??

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