Cooling fans run constantly

[Hokie]

Just today my cooling fans started to run upon starting the car and continues the whole trip. Does this mean my thermostat is stuck open? Can I drive it this way at least for awhile with no damage of any kind? Thanks.

[JohnZ]

I had this issue last weeks, for short trips I used to disconnect the wires at the otterstat, but I had a coolant leak there so I guess that the water made the current keep on flowing regardless of the temperature.

Replacing otterstat and seal solved the problem, but this may not be your case!

;)

[Jonathan]

It probably means that, but some more troubleshooting can (somewhat easily) narrow it down for you.

If the otterstat is the problem and is stuck in a position to tell your fans to stay on, you can test it easily by pulling off the wires on it. Driver's side of engine, coolant pipe lower, near exhaust manifold. Disconnect the electrical and see what happens. You don't need the engine running for this either coincidentally, so you can test in a number of different ways. If they shut off as soon as the wires are disconnected, then this is likely the problem. If they stay on, it's something else.

If they stay on, you could also have a short to ground from the positive wire which effectively tells the fans to turn on too. Or it could be in the other half of the equation which turns your fans on, that being the A/C system.

Try the otterstat test first and report back. Also have a look in your fuse and relay area to see if anything looks melted. Report back what you find.

If the problem was solely your otterstat stuck telling the fans to turn on and nothing else, you can drive like this for now. It's not terribly efficient as you're sending a lot of power to the fans and your fuel mileage will suffer. You might also see more problems if the cause is electrical as you'll be forcing the car to stay in an electrically demanding mode and something else could get melty or problematic.

EDIT: if it is sticking on, it could be an air pocket telling the car the coolant is too hot. Again, easy test while the engine is off and preferably cold as even if it is an air pocket, it shouldn't tell the fans to come on if cold. If it's cold and the fans come on this way, it likely means it's shorted internally for some reason.

[Hokie]

Can someone post a picture of the otterstat? I have no idea what it looks like. Thanks.

[Hokie]

By the way, the fans come on as soon as I turn the key; the car doesn't have to be running. As soon as I switch the key off, the fans shut down, one after the other, within 5 seconds. I have checked the fuse - no problem there.

[jwrayth]

What is your AC Set to? Max AC and fans set to 4 puts the cooling fans on, if I remember correctly?

[Hokie]

What is your AC Set to? Max AC and fans set to 4 puts the cooling fans on, if I remember correctly?

AC is off. Just an update - I found the otterstat, and upon disconnecting the wires, the fans turn off. (cold engine.) Connect the wires, with key on, fans come back on.

[Ron]

AC is off. Just an update - I found the otterstat, and upon disconnecting the wires, the fans turn off. (cold engine.) Connect the wires, with key on, fans come back on.
Time for an otterstat then.

[TTait]

Any time the AC compressor clutch pulls in the fans come on.

With the engine running but not yet warmed up and the AC off open the engine cover - the AC compressor is the belt driven device near the top of the engine on your left side as you look at the engine. The belt and pulley are obviously turning all the time, but there is a clutch that engages the compressor - if the end of the pulley is spinning, then the clutch is engaged and the compressor is pumping - the fans will/should always be on when this happens - if it is not pulled in then thats what you would expect in this mode. Now go turn the AC on and watch the compressor for at least 30 seconds, if the clutch engages and the end of the pulley spins, the fans should turn on with the compressor and turn off when it shuts off.

Knowing what is happening with the AC compressor will help with the diagnostics.

Look at the first diagram here:
http://dmctalk.org/showthread.php?40-All-Wiring-Schematics

You will find a brown orange wire that says to otterstadt that goes to a relay - that is the trigger on the relay that turns on the fan. Now notice that the pink wire from the compressor splices into this wire, so that either the compressor or the otterstat can trigger that relay and run the fans. The triangle and line at the splice point are a diode - like a one way gate. This allows the electricity to tun through the pink wire into the brown orange wire to trigger the relay, but it prevents electricity from going the other way down the ponk wire and turning on the compresser whenever the otterstadt is hot.

The otterstadt is in the silver water pipe a bit below the ac compressor. the water pipe should be installed so that the otterstadt is in the underside of the pipe, so you have to run your hand along its length until you find a sensor plugged into the pipe with two wires in it. That sensor is the otterstadt - it is a temperature switch that closes the circuit when it gets hot, so electricity can glow through it and out the brown orange wire to the relay that turns on the fans. By the way - its worth pointing out that you MUST install a cable tie around the water pipe to help hold the otterstadt in position, or it can fall/shoot out and you will destroy your engine with no warning in just a few minutes. there are other threads on the forum with diagrams if you don't have the cable tie. See posts 32 and 43 in this thread for info on how and why to cable tie your new otterstadt in place...

http://dmctalk.org/showthread.php?848-HELP-Car-Overheated-Today/page4

So - the otterstat can fail such that the fans are always on, or never on. The switch is fragile - if you replace it don't drop the new one. Its easy to check its operation with a meter or a test light. If there is continuity between the two poles when the engine is hot, but now when its cool, hen its generally working properly - any other conditions and it has failed. If the problem is your otterstadt then it has failed such that the circuit is complete even when the engine is cold. Again, easy to determine, with the engine cold and the fans running for no good reason, unhook one wire from the otterstat and the fans should stop.

If the fans keep running, and your AC is off with pulley not turning, then the problem is in the fan relay or fan controller.

Test your otterstadt and see what your AC is doing to see if you can narrow the problem and come back and we can work it out.

BTW - there is no big problem running with the fans stuck on - its just harder on the electrical system but that is not an acute issue - if your fans are stuck off you can get in big trouble fast.

T






Tom

[Jonathan]

By the way, the fans come on as soon as I turn the key; the car doesn't have to be running. As soon as I switch the key off, the fans shut down, one after the other, within 5 seconds. I have checked the fuse - no problem there.

I saw your post after this one mentioning the otterstat wires pulled gets them to shut off. That's good.

This mention here though about one after another and within 5 seconds has me wondering if you have any non-stock fan controller installed in your car? I don't have one myself, and don't know for certain how they work, but the factory set-up didn't stagger them one after the other as far as I know. Perhaps if you have a Joe Cool or Dave (bitsync)'s fan controller they could chime in on whether it might be having a problem too? It might just be the otterstat is shot, but it could be more than that too.

[mluder]

Also... If you do end up replacing the otterstat don't forget to bleed the cooling system or you'll have a whole bunch of other problems...

[JohnZ]

Also... If you do end up replacing the otterstat don't forget to bleed the cooling system or you'll have a whole bunch of other problems...

...unless you don't have an air bleeder on your circuit!

[Iznodmad]

Jonathan, I believe Hokie has a Fanzilla unit. That would explain the sequencing of the fans. We are going to fix this issue at my tech session this Saturday. We will check out the entire cooling and electrical fan connections. No air bleeder either, not yet anyway.

[Hokie]

Also... If you do end up replacing the otterstat don't forget to bleed the cooling system or you'll have a whole bunch of other problems...

Any advice on how to bleed the system? I don't have a bleeder valve, so I'll have to do it some other way. Thanks.

[DMCMW Dave]

Any advice on how to bleed the system? I don't have a bleeder valve, so I'll have to do it some other way. Thanks.

You don't have the one in the thermostat housing?

[Hokie]

Only aware of a bleeder valve above the water pump near the throttle spool, which some folks have but I don't, for some reason. Where is the thermostat housing?

[mluder]

Any advice on how to bleed the system? I don't have a bleeder valve, so I'll have to do it some other way. Thanks.

Even if you have automatic the air bleeder system it's a good idea to bleed manually first. The Automatic system is a maintenance feature and should not be relied on to remove excess air bubble from your cooling system. That being said I highly recommend Toby at DeLorean Part Northwest's re-circulation self bleeding system AND his radiator hose bleeding valve. The bleed valve especially will make your life easier and less messy.

Here's a how to on bleeding the cooling system.
http://delorean2109.blogspot.com/2008/08/burping-your-new-delorean-baby.html


One thing I like to do first is get a pressure testing kit... Autozone will "rent" you one for about $75. They actually sell it to you and then you return it when your finished. Hook the pressure tester up at the coolant tank and then pressurize the system. Then disconnect the smaller upper radiator hose as described in the how-to. This will force some coolant and air out of the system. Benefit here is you are not dealing with HOT coolant. After getting some air out, put the hose back on and clamp it up... Then re-pressurize and do it again. I do this a couple of times before proceeding to the steps in the how-to above.

Also word of caution... If you have the original factory radiator be careful removing and re-installing the radiator hose. The barb is plastic and easily broken. Another reason Toby's radiator bleeder kit is so valuable.

[mluder]

Only aware of a bleeder valve above the water pump near the throttle spool, which some folks have but I don't, for some reason. Where is the thermostat housing?

That's the same one... The thermostat housing is on top of the water pump.

[Ron]

+1 TTait, except:

...
So - the otterstat can fail such that the fans are always on, or never on.
Actually the AC can turn the fans on (but not off) regardless of an otterstat failure...

=====

Hokie, if the fans are ON while the engine is cool, and removing either wire from the otterstat makes the fan(s) stop, the otterstat is bad, period.

[Jonathan]

Jonathan, I believe Hokie has a Fanzilla unit. That would explain the sequencing of the fans. We are going to fix this issue at my tech session this Saturday. We will check out the entire cooling and electrical fan connections. No air bleeder either, not yet anyway.


Any advice on how to bleed the system? I don't have a bleeder valve, so I'll have to do it some other way. Thanks.


Hokie, if the fans are ON while the engine is cool, and removing either wire from the otterstat makes the fan(s) stop, the otterstat is bad, period.

Looks like you're getting a new otterstat, Hokie.

You're in good hands with Darren and others at the tech session. They'll show you what you need to know about bleeding the cooling system.

[DMCMW Dave]

Only aware of a bleeder valve above the water pump near the throttle spool, which some folks have but I don't, for some reason. Where is the thermostat housing?

That IS the thermostat housing. I've never heard of that one "going missing" but I suppose someone could have broken it off flush or filled it with a bolt.

If that's gone or frozen, you can (a bit messier) bleed it by loosening the hose clamp on where the large driver-side hose attaches to the water pump.

[TTait]

+1 TTait, except:

Actually the AC can turn the fans on (but not off) regardless of an otterstat failure...

=====

Hokie, if the fans are ON while the engine is cool, and removing either wire from the otterstat makes the fan(s) stop, the otterstat is bad, period.

Agreed - did not mean to imply otherwise. Thanks for the clarification.

[AirmanPika]

I had this same fan issue when I first got my DeLorean. I guess it was good that the fan was stuck on vs stuck off (imagine the overheats). Ended up being a bad otterstat as some have mentioned. When I removed it, I found that the housing had actually split open. I swapped it out and it was golden again. I replaced the connectors at the same time as my old ones had corroded and the plastic broke away.

I'm glad I read this thread...I probably need to do a bleed on my DeLorean's cooling system once I return stateside in a few weeks. I installed one of the auto bleeders but I only keep it on for short periods. I just gotta remember how the thing works again :)

[Hokie]

Does anyone know if the otterstat has to be oriented a certain way? There are two connectors, does one have to be on the right and the other on the left, or does it matter? Another way of saying it, there are two wires - does it matter to which connector each wire is plugged into? Thanks.

[Bitsyncmaster]

Does anyone know if the otterstat has to be oriented a certain way? There are two connectors, does one have to be on the right and the other on the left, or does it matter? Another way of saying it, there are two wires - does it matter to which connector each wire is plugged into? Thanks.

Wire connections are interchangeable. Works both ways just fine.

[Hokie]

Wire connections are interchangeable. Works both ways just fine.

Thanks! Of course it helps if the vendor sends you a part that's not faulty.

[Rich]

Does anyone know if the otterstat has to be oriented a certain way? There are two connectors, does one have to be on the right and the other on the left, or does it matter? Another way of saying it, there are two wires - does it matter to which connector each wire is plugged into? Thanks.

You were asking about how the wires to the 'stat are connected and that got answered.

Did somebody already mention that the tee/pipe that holds the Otterstat should be oriented with the 'stat fitting facing down? Terminals facing the ground, that is.

It's a 3 minute fix if you need it.

No need to reply if yours is OK or somebody covered that.

[Riley88]

I have been having a similar problem with my D. She drives fine, but recently the cooling fan fail light intermittently turns on and off. it will stay on then go off then back on. I had a question, when the fans are reporting a fail, is this a hard fail, or is it like if they arent spinning at a certain rpm ( example my radar i work on if our fans dont spin at least a 2300 rpm and drop below that threshold we get a warning even if its spinning at 2100). So for a delorean, are the fans required to spin at a certain speed?Or is does it mean it completely isnt spinning? I am taking the car to be serviced at dmc LA in huntington beach. its a 1.5 hour drive just want to be sure if its safe for me to make that journey

[Bitsyncmaster]

I have been having a similar problem with my D. She drives fine, but recently the cooling fan fail light intermittently turns on and off. it will stay on then go off then back on. I had a question, when the fans are reporting a fail, is this a hard fail, or is it like if they arent spinning at a certain rpm ( example my radar i work on if our fans dont spin at least a 2300 rpm and drop below that threshold we get a warning even if its spinning at 2100). So for a delorean, are the fans required to spin at a certain speed?Or is does it mean it completely isnt spinning? I am taking the car to be serviced at dmc LA in huntington beach. its a 1.5 hour drive just want to be sure if its safe for me to make that journey

Do you have the original fan fail unit installed or do you have my unit (it has fuses on the top). It would be the blue relay looking item in the relay compartment.

[Riley88]

Do you have the original fan fail unit installed or do you have my unit (it has fuses on the top). It would be the blue relay looking item in the relay compartment.

I will need to go check, ill do it right now

[Riley88]

Do you have the original fan fail unit installed or do you have my unit (it has fuses on the top). It would be the blue relay looking item in the relay compartment.


This is what i have
31792

[Bitsyncmaster]

This is what i have
31792

That is the original fan fail unit. It is known to cause failure of the cooling fans and was recalled to remove it and install jumpers in it's place.

[Riley88]

Well do you think i will be safe to drive 1.5 hours to dmc in huntington beach? Its been driving fine, ive owned the car only a few weeks. Its been a real adventure so far everything i ever dreamed. Been doing what mechanical stuff i can. This one i was a little unsure. She doesnt overheat when i drive but that light scares me tbh. Im reading more into this unit. its a reed relay which is Normally open. hmm

[Bitsyncmaster]

Well do you think i will be safe to drive 1.5 hours to dmc in huntington beach? Its been driving fine, ive owned the car only a few weeks. Its been a real adventure so far everything i ever dreamed. Been doing what mechanical stuff i can. This one i was a little unsure. She doesnt overheat when i drive but that light scares me tbh.

If it was me, I would make up the jumpers (I'm looking for the info). What you risk is both fans failing and then overheating the engine. Maybe it's just one fan circuit failing which may be enough to keep the engine cool.
An overheated engine is an expensive fix that requires head gaskets and maybe more.

[Riley88]

If it was me, I would make up the jumpers (I'm looking for the info). What you risk is both fans failing and then overheating the engine. Maybe it's just one fan circuit failing which may be enough to keep the engine cool.
An overheated engine is an expensive fix that requires head gaskets and maybe more.


I think i will, its a short drive, but i want to do it safe. Im still learning where to buy parts. I snapped my throttle cable a few days ago, so i ordered a new inner cable and replaced it fine. Of all the things on my plate this is the only real serious issue. You a huge help, thank you

[Bitsyncmaster]

I think i will, its a short drive, but i want to do it safe. Im still learning where to buy parts. I snapped my throttle cable a few days ago, so i ordered a new inner cable and replaced it fine. Of all the things on my plate this is the only real serious issue. You a huge help, thank you

Make sure you scan your gauges all the time and if you see the temp gauge go up, pull off the road.

Here is the jumper info:
http://www.dmcnews.com/bulletins/ST-06-9.82.html

[Riley88]

well ill do just that wont drive until i go up there tomorrow. I always keep an eye on my gauges! Thank you, ill bring this up to the folks @ huntington beach dmc. Thanks again, HUGE help.

[iflights]

Found the most relevant thread I could. My problem is that the fans don't shut off after 20 seconds when the car is shut down. They keep running...forever. I have Dave's fan fail and fan relay modules. When I remove the fuses from the fan fail module the fans stop. If I put fuses back in the fans run forever, without the car running.

Sounds like it might be either fan fail or relay module with these symptoms.

Any thoughts?

Thanks

[sdg3205]

I think another owner had some issues with daves fan fail update. I believe there is a fix, so talk directly with Dave McKeen.

[iflights]

Will do, thanks. After I wrote about this, I did isolate it to the fan relay itself, not fan fail. I replaced the new solid-state fan relay with the Tyco relay I took out, and fans acted normal and shutting down when engine is off.

I'll reach out to Dave.