Radiator fans not turning on

[DMCVegas]

With my car, the heater has never had a good output of warm air in the winter. The temp doesn't get much over the first line on the gauge.
I suspect that my thermostat is stuck open. (It runs nice and cool in the Hot Alabama summers)...

George

Yes, that is NOT good at all! I will refer back to the fire triangle:



A fire of course needs Fuel, Heat, and Oxygen to occur. But that is merely for a simple flame. Smoke of course isn't simply a byproduct of a fire, it's a symptom of an incomplete burn. Smoke is simply just unburned fuel floating away. For proper combustion to occur within an engine's combustion chamber, you MUST have the heat at it's minimal operating temperature inside of the chamber. This ensures that all of the fuel is completely burned. If the temperature is NOT hot enough, then not all of the gasoline gets burned off before it exits out of the exhaust valves, and it starts to deposit itself on the valves and pistons as carbon deposits (think smoke).



To say that this is bad is the understatement of the year. As carbon built up, it causes all sorts of problems. The first is going to be that it will prevent your valves from closing all of the way, and you can loose compression. The second is that carbon retains heat, so it causes pre-detonation of the gasoline before the spark plug activates. So to counter that, you have to start using mid-range fuels with higher octane ratings, and it costs you more.

Running cold on an engine is NOT a good idea in the least! You WILL end up with permanent damage. My suggestion would be to swap that thermostat out, and then start running Techron though a few tanks with the engine up to full temp at 218°F.

I wonder if bad grounds at the fans, or dirty fans (inside) also cause the higher amperage load/melting?

Someone please correct me if I am wrong, but I do believe so. At the back of the fans, on the bottom there are drain holes. I noticed after a few rounds of floodwater (and who knows WHAT the PO went though with this car, but it did have sand and silt everywhere being a desert car) my fans didn't run very well. Noticeable lower CFM output until the passenger side stopped working entirely. I killed power and unplugged the fans and then sprayed this stuff up inside of the hole:



The gunk that came out was nasty! But I was able to keep the fans going for a while longer. Granted now if your fans are pulling this much of a load, and/or are in the condition that mine were, it's time to replace them. You can now get replacement fans with higher CFM ratings that consume less power. Or if you prefer, take yours out and get them serviced at a repair shop. It's a no-brainer to start replacing the 35 year-old electrical components at this point.

Coolant level is good. I haven't checked to see the if the core is bypassed. I wanted to but wasn't exactly sure what do look for.

Refer to section 7-1-3 of the parts manual to see where the lines for the Heater Core are run.

[mr_maxime]

I jumped it with a paperclip and the key was in the accessory position. The fans were on when I turned the key cause the AC was on. I turned the AC off and nothing happened when I jumped it.

[DMCVegas]

I jumped it with a paperclip and the key was in the accessory position. The fans were on when I turned the key cause the AC was on. I turned the AC off and nothing happened when I jumped it.

Click it forward to the ON Position.

[funkstuf]

You're right. Sometimes the circuit breaker will trip until it cools down. I burned my fingers badly on it once.

Dave,
This sounds like what's happening on this car, and I seem to remember that heat trips the circuit breaker, not just amperage. Thus, no blown fuses, but fans stay off until the breaker closes again. In my car, I kept the compartment cooler by leaving the lid off, and ran the fans longer by turning the otterstat down, and the end result was fans that ran longer, but melted the wires all around the 15 AMP fuses. I have noticed that the wires no longer heat up since putting in the new fans. I suppose over-hauling the OEM fans was an option, and may do this, but I liked the idea of the lower current fans.

[Bitsyncmaster]

Both fuses and circuit breakers work by introducing some resistance that cause more heat with increasing current flowing through that resistance. A fuse just melts the connection "element" when it gets hot enough (has to much current). The circuit breaker heat up a bi-metallic strip of metal that causes it to bend and break contacts to open the circuit.

Both will get to hot to touch when running close to the rated breaking current.

I seem to remember testing that both the fuse and breaker introduce close to the same resistance so produce close to the same amount of heat but the fuse is smaller so it's hotter to the touch.

[mr_maxime]

Click it forward to the ON Position.

I did and jumped the otterstat with a paperclip. The fans did not turn on.

[DMCVegas]

I did and jumped the otterstat with a paperclip. The fans did not turn on.

I usually prefer to us a bit of wire to ensure a proper connection for testing. But at this point you would now need to test the wiring and the fans with some tools. You'll need a voltmeter and a wire jumper with a couple of spade connectors crimped onto the end. And most importantly of all, the Wiring Schematic.

Traditionally, this is the method you would use to track down an electrical problem: What we need to do first is disconnect the radiator fans, insert the jumper into the clips for the otterstat, and then measure if you have 12V coming through. However, I would recommend that you check using an alternate ground other than what the connectors supply. That way we can rule out a bad ground. If you get 12V with an alternate ground, clean your front grounding points and start over (though keeping grounds clean is still a good idea anyway if you haven't ever done it).

The next thing we need to look at from there is going to be the Fan Fail Relay. Which of course should be gone and instead replaced with a Y-Jumper wire. Measure to see that you have 12V there, and run a test jumper to test.

Down the list we need to move onto the Circuit Breaker, and eventually the Cooling Fan Relay itself. However, you made mention that the fans *did* previously work while on the MAX A/C position. The fans turn on when the Cooling Fan Relay gets triggered by a 12V feed from either the Otterstat, or the A/C system's Low Pressure Switch (they use diodes to prevent feedback). MAX A/C shouldn't have any effect on the cooling fans to make them function any different.

So do me a favor and try this directly:

1. Verify that you have no blown Fuses.
2. Check all electrical connections. Make sure your fans are plugged in snug and clean, and just as importantly, open the relay box and verify that the Fan Fail Jumper is correctly installed and seated properly.
3. Insert a wire jumper to bypass the Otterstat again and see if the fans turn on. If not, proceed to the next step.
4. Bypass the Circuit Breaker and see if your fans turn on.

If the fans turn on when you've bypassed the circuit breaker, that's good. But you're not out of the woods just yet. The next step is you're going to need to test your fans to see how much amperage they draw. Pull the Fan Fail Jumper, and then use a Multimeter in it's place to test how many Amps each fan is pulling down. If your fans are in spec, you'll just need a new Circuit breaker.

If your fans did NOT turn on when you bypassed the circuit breaker, then the next step will be to move on to the Cooling Fan Relay, and insert a jumper wire to see if they come on. That will tell you if you simply have a bad relay.

[mr_maxime]

I was an idiot. I didn't jump the wires leading to the otterstat, I jumped the spades on the otterstat. So when I actually jumped the wires, the fans came on. Wasn't really thinking about it, but when I actually thought about it I realized the otterstat probably works by jumping the wires when the coolant reaches a certain temperature.

I did check the fuses again and they were fine. I switched the low beam relay with the cooling fan relay, both new purple ones, just to make sure it wasn't the relay. I reseated the fused fan fail wires. I don't have access to a voltmeter right now I can't really get more thorough.

[DMCVegas]

It happens. I've done things like that as well, so don't sweat it.

You are absolutely correct about the function of the Otterstat. Water temperature trips it to close those two wires to turn the fan on. So at this point you're down really to these things:

• Hot water not reaching Otterstat to trip it.
• Bad Otterstat.
• Bad Circuit Breaker.
• Bad fans drawing too much amperage.
• Loose wires.

*Hot water is really only a concern if you have an early VIN with the Renault pipe that runs next to the A/C compressor and has the Otterstat on top. Or your coolant lines are empty. So I'm pretty sure we can rule this out.
*You might just have a bad Otterstat. That is a possibility, and it is one you can test by placing the Otterstat into boiling water with a thermometer to see at what temperature it finally closes the circuit at.
*You might have a bad circuit breaker that is prematurely tripping. Your engaging the A/C and getting the fans to work would *technically* negate this however, but that leads me to...
*You might have bad fans that are consuming way too much power. That could cause the circuit breaker to trip. But as the circuit breaker cools down, it automatically resets itself, and that might have been a coincidence with the A/C possibly. Testing with a voltmeter is the best thing to do. But I will also tell you that cleaning your electrical connections is also a good idea. Get your grounding points clean, and also make sure that you clean all of the contacts for fuses and relays inside of your electrical compartment. Insert and remove fuses and other spade connectors repeatedly to clean out sockets. Anything you can scrub, use a regular pink latex pencil eraser. It works great.
*But most of all too, you might just have some loose wires. I know because this happened to me. Long story short, the jumper came loose and my fans failed to turn on. So I just crimped together a new jumper and away I went. Although I did ever so slightly warp the spades by bending them with some needle nose pliers to make sure they wouldn't back out on me again.

Using the list above, I'd recommend you go backwards. Check for loose wires, check amperage draw, and then go on to check your Circuit Breaker and Otterstat.

[john 05141]

I do not want to steel this thread.

I have the original fans too. plus a manual switch in my console already a few years.
Now the fans still come on manually, but not when I turn on the AC
The fan fail light lights up slightly

All fuses are OK

Anyone hase any suggestions?

Jan