Radiator fans not turning on

[mr_maxime]

I have the fused fan fail relay and I think a new otterstat switch, but my fans won't kick on. The car overheated in traffic several weeks ago but after letting it cool and restarting the car they kicked on again. I normally do a lot of highway driving so this issue didn't pop up again until today. I checked the wiring of the fan fail relay and all of the fuses. I checked the otterstat and the connections looked good.

[funkstuf]

I have the fused fan fail relay and I think a new otterstat switch, but my fans won't kick on. The car overheated in traffic several weeks ago but after letting it cool and restarting the car they kicked on again. I normally do a lot of highway driving so this issue didn't pop up again until today. I checked the wiring of the fan fail relay and all of the fuses. I checked the otterstat and the connections looked good.

If you have the old fans I suggest getting the lower current version. I used to have this problem at times and found that the relay was getting too hot. If I left the cover off the relay/fuse housing area it would work better, but a bit bothersome. Someone else I know told me they put a fan in the relay/fuse box area with some holes to vent the heat and it helped. I ended up buying the new fans because even with the fan fail fix the wires in my car melted near the fuses. That's because the current draw is not high enough to pop the fuses, but if the fans are worn and run too much it overheats the wires and they melt. I've seen this happen a couple of times, most recently in a car with original fans that was in a parade last year in the summer. The new lower current fans solve this problem.

[sdg3205]

You should jump the spades at the otterstat to ensure the fans run on demand.

[Jonathan]

You should jump the spades at the otterstat to ensure the fans run on demand.

Yes, good suggestion.

Do this test to confirm they come on with the otterstat, and also do a similar test to see them come on with your A/C.

Assuming your A/C is working (if it isn't, then disregard), have your HVAC mode control knob set to MAX A/C and the temperature all the way clicked to cold, and then without starting the car, turn the key to accessories and you should hear the compressor clutch clack in and the fans running.

[mr_maxime]

At max AC they turn on. I had it on vent last night so that may at least be a temporary fix if I get caught in stop and go. Does the engine need to run when I'm jumping the otterstat?

[sdg3205]

At max AC they turn on. I had it on vent last night so that may at least be a temporary fix if I get caught in stop and go. Does the engine need to run when I'm jumping the otterstat?

I'm not convinced running the AC to get the fans to run does much good to help an overheating condition. You're adding load AND adding a hot condenser to cool down. I'd jump the fans AND run max heat and add another radiator into the equation.

No, if you jump the fans the will run on the key ON position.

[DMCVegas]

At max AC they turn on. I had it on vent last night so that may at least be a temporary fix if I get caught in stop and go. Does the engine need to run when I'm jumping the otterstat?

Nope. Power to the fan circuit does NOT run through the RPM Relay, so the engine does not have to be running to activate the fans.


I'm not convinced running the AC to get the fans to run does much good to help an overheating condition. You're adding load AND adding a hot condenser to cool down. I'd jump the fans AND run max heat and add another radiator into the equation.

I actually mostly agree with you on this this, but for an entirely different reason.

The cooling system is designed to withstand the load of the engine, AND the Air Conditioning at the same time. To remedy an overheating engine, no, it isn't the best idea, but if it's needed to get the fans running, then go ahead and do it.. But never when set to MAX!

When your engine overheats (and by overheat in this case we mean go past 220, but not yet blow the radiator cap) what you want to do is actually crank the heater all the way up to it's maximum setting. Your Heater Core is of course a small radiator which works on the exact same principal as your large one up front. So when you crank the heat up and divert air over across it, you're still cooling a decent amount of water. Not enough to run an engine properly, no, but definitely enough to take the edge off, and in some cases avoid overheating all together and avoiding popping a radiator cap so that you're not stranded. This is especially true of older, and even late-model cars with thermocouple fans where you're going up a hill and start to run too hot and just need to make it over the crest.

Running the A/C isn't the best idea, but if it's needed to run electric cooling fans to get the engine back down to temp, that's better than nothing. EXCEPT when running it on MAX. And the reason is this right here:

https://store.delorean.com/images/Product/medium/100763.jpg

This isn't just a DeLorean thing, it's an every car thing. That's the water valve that feeds the hot water supply into the Heater Core. Water is always flowing through the Heater Core, unless you've got MAX A/C turned on. At that point, aside from closing the damper door to recycle internal air only, it also closes the Hot Water Valve pictured above. So when that valve closes, and no water flows through the heater core, then you can't use the heater for additional cooling.

[mr_maxime]

Alright I'll jump it tomorrow. Running the heat probably isn't an option since the heat doesn't work in my car.

[DMCVegas]

Alright I'll jump it tomorrow. Running the heat probably isn't an option since the heat doesn't work in my car.

http://static4.fjcdn.com/comments/Wow+i+honestly+didn+t+know+that+when+i+posted+it+_ 10940d3a6d388d14a0051d4855786c52.png

Is your Hot Water Valve just stuck in place? Or are you that low on coolant?

[sdg3205]

http://static4.fjcdn.com/comments/Wow+i+honestly+didn+t+know+that+when+i+posted+it+_ 10940d3a6d388d14a0051d4855786c52.png

Is your Hot Water Valve just stuck in place? Or are you that low on coolant?

Or is the core bypassed?

[DMC-81]

I can vouch for the heat on max trick to mitigate an overheating problem. Long ago I had a Jeep Cherokee and it began overheating on a highway though the woods late at night (no place to get help for an hour's drive). I cranked the heat to max and opened the windows. Although it was wintertime up North, the air coming out of the vents was hot! I also tried to keep the engine speed as low as possible using 5th gear.

This did the trick and it kept the temperature gauge below the critical zone. I watched the gauge for an hour till I got back to civilization. It turned out to be the thermostat that failed in the closed position.

Anyway, here is a picture of the D's otterstat jumpered if it helps:

41494

[refugeefromcalif]

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

[David T]

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

Stuck open or maybe not even there! The motor really should be run at operating temperature for best fuel economy and longevity. Too hot is not good but too cool is not good either.

[funkstuf]

I like all the ideas above and I tried them all at one point or another, but, if the fans always kick on the first cycle or two, then stop working, then turn on again after the car sits for awhile, it suggests that the fuse/relay area may be getting too hot. I actually thought I needed to run my fans more so I used a variable otterstat that made my fans run more (similar to shorting the otterstat). Eventually, the wires at the fan-fail fuses melted, but the fuses remained intact. Shorting the otterstat will run the fans a continuously. I suggest after running continuously for awhile check the fuse wires on the fan fail (touch them) and see how hot they are and make sure they're not melting. I could never figure out the problem, but saw it happen to another PNDC member exactly as it had on mine. We both had the original fans and replacing the fans with new lower amperage fans solved the problems.

[sdg3205]

I like all the ideas above and I tried them all at one point or another, but, if the fans always kick on the first cycle or two, then stop working, then turn on again after the car sits for awhile, it suggests that the fuse/relay area may be getting too hot. I actually thought I needed to run my fans more so I used a variable otterstat that made my fans run more (similar to shorting the otterstat). Eventually, the wires at the fan-fail fuses melted, but the fuses remained intact. Shorting the otterstat will run the fans a continuously. I suggest after running continuously for awhile check the fuse wires on the fan fail (touch them) and see how hot they are and make sure they're not melting. I could never figure out the problem, but saw it happen to another PNDC member exactly as it had on mine. We both had the original fans and replacing the fans with new lower amperage fans solved the problems.

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

[Bitsyncmaster]

I like all the ideas above and I tried them all at one point or another, but, if the fans always kick on the first cycle or two, then stop working, then turn on again after the car sits for awhile, it suggests that the fuse/relay area may be getting too hot. I actually thought I needed to run my fans more so I used a variable otterstat that made my fans run more (similar to shorting the otterstat). Eventually, the wires at the fan-fail fuses melted, but the fuses remained intact. Shorting the otterstat will run the fans a continuously. I suggest after running continuously for awhile check the fuse wires on the fan fail (touch them) and see how hot they are and make sure they're not melting. I could never figure out the problem, but saw it happen to another PNDC member exactly as it had on mine. We both had the original fans and replacing the fans with new lower amperage fans solved the problems.

A friend also had his jumpers melt and also flames from them. He also had OEM fans and I tested the currents and they were about 14 amps each. So either his fuse box gets really hot or the fans have an intermittent that makes the current go higher sometimes. I suspect the fans have intermittent high current. I installed a spare set of low power fans I had so I still have his OEM set. I may someday do some testing on those OEM fans. I wonder if it's just brush dust shorting the commutator. The low power fans draw 7 or 8 amps each.

[DMC-81]

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

When I refurbished that area, my fans also worked intermittently. When I spun them while the car was off there was resistance and there was a gritty sound. I took both of them apart, and found some dirt and rust particles sticking to the magnets. I cleaned all of the inside and also the brushes. Then I used a small amount of machine oil on the shafts. While it was apart, I sanded and repainted the cases. I also traced the grounds to the frame connection and cleaned that. I replaced the frame bolt with SS and used di-electric grease.

Anyway, now both fans work like new and the wires at the fan and the fuse area are cool. All for $10 in paint and a few hours of my time.

I remember Andre of the delorean world tour mentioning that they run the OEM fans because they pull more air, and they are user repairable.

Of course, YMMV, and I'm sure at some point they are too rusted/worn out, but I thought I'd share my experience with them. Here's a pic:

41498

[Bitsyncmaster]

Passive components (motors, light bulbs, etc.) will draw less power when you have bad connections on 12 volts or grounds. The bad connections have resistance which cause voltage drops and less voltage at the load.

Switching regulators will draw more current with bad connections because lower input voltage needs more current to keep the output voltage at normal levels.

[hmcelraft]

Long ago I found that the fused fans plus a circuit breaker combination with a single relay was too hot and too unreliable. This was after the fan fail relay and OEM circuit breaker melted down shortly after I bought my first new DeLorean in Jan of 1982.

Initially I tried it all --- the modification using fuses (melted several times) the 40 amp circuit breaker, etc. In 1983 or 1984 I rewired the fans for a single relay each and a single 15 amp HD circuit breaker for each fan. Finally low heat and measured amperage at the fans about 11-12 amps each. I wired the fans to come on and run continuously while the AC was turned on and work normally when the AC was turned off. I lived in Houston and the AC was on virtually year-round anyway. I replaced the fans once at about 60,000 miles (I could have rebuilt them - just brushes worn out). I sold the car in 1988 with 95,000 miles on the car and they were working great. I had acquired another 5 speed from my dealer in 1984 and had modified the wiring similarly. It had about 40,000 miles on it when it was sold. No issues with fans. The Automatic I have now, acquired in 1987 with 8,000 miles on it, has my modified wiring method applied to it -- plus, I decided to run the power supply wires directly from the battery. Early last year (about 97,000 miles) I replaced the fans with some NOS OEM fans I had because I was changing the radiator and didn't want to mess with fans in the future. The brushes were in fact worn out on one of the fans. My point to this is that the OEM fans work well if you can get sufficient wiring to them - even though their normal amperage draw is bit high.

As far as electrical strain. I haven't really had an issue. Early days I ran the Motorola alternator and had no issues. I had a Motorola on this current car and I switched to the Delco 130 version because I was afraid the Motorola was wearing out and the Delco version gives me some reserve.

[mr_maxime]

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.

[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:

http://www.belson.com/Images/Fire-Triangle.png

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).

http://i1081.photobucket.com/albums/j344/eric271828/Yamaha%20XT500/Cylinderhead.jpghttp://i772.photobucket.com/albums/yy9/FrozenTows/EngineCarbon.jpg

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:

http://www.crcindustries.com/catalog/images/Cleaners%20and%20Degreasers/05018.jpg

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:


Verify that you have no blown Fuses.
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.
Insert a wire jumper to bypass the Otterstat again and see if the fans turn on. If not, proceed to the next step.
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

[mr_maxime]

I still had some credit, so I ordered new fans from DPI. Might not solve the problem, but it gets the big ticket item out of the way and upgrades the car.

PS:I'll be a full-time employee again starting monday and I'll soon be able to start sinking money into my beloved delorean again!

[Timebender]

I'm having the same issue now. When I got my car last year, the fans weren't working. Danny replaced the otterstat and I believe the fan relay (the purple one). When I got the car back all was working well, but now the fans aren't working again. I did notice when I changed my thermostat (I have a Chevy 350), there was no coolant in the hose - it was dry as a bone. After changing it, I ran the engine and the pipe where the otterstat is did get nice and hot, but still no fans and the temp got above 220. I'll try jumping them today and see if they come on, but if not, could it be the relay is bad, or is there a fuse that could be blown?


Sent from my iPad using Tapatalk HD

[David T]

I'm having the same issue now. When I got my car last year, the fans weren't working. Danny replaced the otterstat and I believe the fan relay (the purple one). When I got the car back all was working well, but now the fans aren't working again. I did notice when I changed my thermostat (I have a Chevy 350), there was no coolant in the hose - it was dry as a bone. After changing it, I ran the engine and the pipe where the otterstat is did get nice and hot, but still no fans and the temp got above 220. I'll try jumping them today and see if they come on, but if not, could it be the relay is bad, or is there a fuse that could be blown?


Sent from my iPad using Tapatalk HD

No way to know from here if your wiring was modified from stock. The cooling fans get their power from the circuit breaker next to the one for the heater fan. The power comes from the alternator to the fan relay, through the circuit breaker and then the fan fail relay and finally to the fans. The fans are control3ed by either the otterstadt switch or the A/C compressor, either can make the fans run.

[Timebender]

No way to know from here if your wiring was modified from stock. The cooling fans get their power from the circuit breaker next to the one for the heater fan. The power comes from the alternator to the fan relay, through the circuit breaker and then the fan fail relay and finally to the fans. The fans are control3ed by either the otterstadt switch or the A/C compressor, either can make the fans run.

DMC Ca was able to get them to run in the past. I'll jump the otterstat and see if that's it, and then check the relay. The one to the far left which I assume is where the fan fail relay goes, is jumped with a couple wires already.

[GR8SCOTT]

I had a similar issue & it was a simple fix for me. I cleaned the contacts on the two 1 amp diodes in the relay compartment. Voila!

http://uploads.tapatalk-cdn.com/20160516/f951f1e56bfd0f28bd85bee8b487fc0c.jpg

[Timebender]

I'll give that a shot tomorrow too! I didn't even know about those. Thanks!


Sent from my iPad using Tapatalk HD

[Timebender]

Problem solved - bad thermostat wasn't allowing any coolant through to the otterstat.