Fan Fail Jumper - WARNING

[Ras12]

Every year I check the fuses and relays as a precaution and look what I discovered this year!

Looks like the jumper isn't a safe bet either. Funny thing is I have a Special T Fan Fail I was going to post for sale too because I was thinking on going with Dave's solid state or electronic Fan Fail. Good thing I checked.

Next step now is to find a source to replace the blue relay socket.

Any idea where I can find one?

Also, between the 2 that Dave sells which is better the solid-state or electronic fail?

[Christian Dietrich]

I have the solid state and a bunch of his electronics in my car. If you get the blue or green LED HVAC panel upgrade he also sells along with the solid state, the fan logo for the vent system lights up to tell you the fans are on. I have the blue led panel so the fan logo lights up green.http://uploads.tapatalk-cdn.com/20160607/8e60408e888e5ca1cc64c2848dcc7834.jpg

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[Ras12]

I have the solid state and a bunch of his electronics in my car. If you get the blue or green LED HVAC panel upgrade he also sells along with the solid state, the fan logo for the vent system lights up to tell you the fans are on. I have the blue led panel so the fan logo lights up green.http://uploads.tapatalk-cdn.com/20160607/8e60408e888e5ca1cc64c2848dcc7834.jpg

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Very cool idea! I didn't realize the fan logo would illuminate too.

[mr_maxime]

Aren't the jumpers supposed to be fused?

43533

[Christian Dietrich]

Aren't the jumpers supposed to be fused?

43533
Originally yes but they always seem to melt before they will ever blow.


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[Christian Dietrich]

Very cool idea! I didn't realize the fan logo would illuminate too.
I didnt know either till i saw it happen. I contacted him and you forgot to tell me LOL and Dave used to live only 45 minutes away from me when I still lived in Maryland until I moved Last Summer but I have just about every one of his updates that he's put out there and I've never once had a failure with anything he sells.

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[Bitsyncmaster]

Usually the jumpers just burn the one power feed pin because that pin has the current of both fans. It worries me your fans are each drawing to much power since all three pins are showing heat. Maybe your jumper wires are to small (should be AWG 14 or larger).

You don't need fuses if you keep the stock fan circuit breaker but fusing each fan lets you know if one fan is a problem.

I think OEM fans will draw to much current after they age (long run time). I suspect the commutator on the fan motor develops shorts filling with dust from the brushes so that high current is intermittent. One owner had the one pin jumper start a fire burning the insulation of the wire. I measured his fan currents and each was about 14 amps. New OEM fans seem to run about 10 amps.

You will need to install new relay socket connectors along with a new plastic relay socket. I recommend you upgrade to one of the vendors "low power" fans.

I have some good used relay sockets but don't have a blue one.

[content22207_2]

Aren't the jumpers supposed to be fused?


Originally yes but they always seem to melt before they will ever blow.

Actually, no: http://www.dmcnews.com/bulletins/ST-06-9.82.html

Putting fuses in is a later community practice, not factory OEM.

I do agree they are failure prone and unnecessary because the circuit is already breaker protected.

Bill Robertson
#5939

[Christian Dietrich]

Yeah and it actually doesn't protect anything

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[content22207_2]

If you're not going to use the socket to attach a module of some sort I recommend pulling the wires out and connecting them together directly.

Bill Robertson
#5939

[Elvis]

The cars I had in my fingers all got two relays - one for each fan and a fuse or CB also one for each fan.
I used the blue socket for the extra relay.

This reduced the current and therefore heat on the wires and terminals that originally have to conduct the
current for both fans.

reliable for 10 years now - with stock fans.

[David T]

The jumper for the fan Fail Relay was only supposed to be a temporary fix till the factory could come up with a more permanent solution. That was over 30 years ago! Not bad for a temporary solution! Fanzilla was a great after-market solution but they are no longer available. Many cars are still running the jumpers and a few even still have the Fan Fail Relay! The jumpers will eventually burn. On one car I know of it even smoked! Scared the h-ll out of the owners. The whole fuse/relay area must be checked at least annually for signs of overheating. PJ Grady is working on a modern replacement for the Fanzilla and bitsyncmaster has one now. Even if you have a module you still need to inspect that area regularly, the fuseblock can still melt. Also you should have the relay upgrade kit installed and leave the cover off of the fuses. The jumper does not really need the fuses, as Bill said, it was someone's good idea, but I have never seen the fuses blow but I HAVE seen the connectors melt!

[mr_maxime]

The jumper for the fan Fail Relay was only supposed to be a temporary fix till the factory could come up with a more permanent solution. That was over 30 years ago! Not bad for a temporary solution! Fanzilla was a great after-market solution but they are no longer available. Many cars are still running the jumpers and a few even still have the Fan Fail Relay! The jumpers will eventually burn. On one car I know of it even smoked! Scared the h-ll out of the owners. The whole fuse/relay area must be checked at least annually for signs of overheating. PJ Grady is working on a modern replacement for the Fanzilla and bitsyncmaster has one now. Even if you have a module you still need to inspect that area regularly, the fuseblock can still melt. Also you should have the relay upgrade kit installed and leave the cover off of the fuses. The jumper does not really need the fuses, as Bill said, it was someone's good idea, but I have never seen the fuses blow but I HAVE seen the connectors melt!

Is the burning only with the stock fans?

[David T]

Is the burning only with the stock fans?

The stock fans draw a LOT of current. More modern fans draw a fraction of the current and would be a LOT easier on the electrical system. So, yes, the replacement fans would not burn things up.

[DMCVegas]

The stock fans draw a LOT of current. More modern fans draw a fraction of the current and would be a LOT easier on the electrical system. So, yes, the replacement fans would not burn things up.

And that's when they're brand-new. Add 35 years of dust, dirt, water spraying up, and general wear and tear, and it's going to be worse.

I'm thinking that we should probably start to add Radiator Fans to the list of standardized upgrades along with the Relays and other Kits.

[content22207_2]

Battery outgasses directly underneath the relay compartment. Causes oxidation and corrosion on anything and everything exposed to the atmosphere (such as relay terminals).

Lotus put a venturi tube to vent the battery compartment into the passenger wheel well, but you of course need to drive the car for it to do anything. If your car sits for extended periods of time the venturi tube is guaranteed not to vent anything. Even under the best of circumstances venturi tubes (such as old fashioned gas tank vent tubes) are minimally effective -- there's just not enough pressure differential. Tube is in the side of the battery compartment anyway, not the top.

Bill Robertson
#5939

[Bitsyncmaster]

Is the burning only with the stock fans?

I have seen photos of about 5 to 10 burned fuses and or blue sockets melted and those have always been running OEM fans. Never heard of one burning with "low power" fans.

[content22207_2]

Even under the best of circumstances venturi tubes (such as old fashioned gas tank vent tubes) are minimally effective -- there's just not enough pressure differential.

Same with the factory radiator bleed line. That's why owners are manually bleeding their radiators.

Bill Robertson
#5939

[Mark D]

Sounds like I should be looking at some new fans to replace my stock ones...it's been on my to-do list for at least 5 years and I'm probably overdue.

What's the easiest way to test amp draw on the fans?

[Elvis]

use the search and find the work others have already done


or use a current clamp

[Bitsyncmaster]

Sounds like I should be looking at some new fans to replace my stock ones...it's been on my to-do list for at least 5 years and I'm probably overdue.

What's the easiest way to test amp draw on the fans?

The clamp on amp meters are the best way to measure the high currents. You can get them pretty cheap for DC only currents. I have an expensive one that that I can attach my oscilloscope to and measure current rise and fall times.

[hmcelraft]

On 3 DeLoreans over 35 years, I rewired the OEM fans to each run on a separate relay and a separate 15amp circuit breaker with post and nut connections. I switched the power to come directly from the battery. I rebuilt 2 fans and replaced 2 on car 1 - a 90,000 mile car driven daily in Houston for nearly 8 years. No issues on car number 2 over 36,000 miles and on car 3 with 117,000 miles I replace both OEM fans with NOS fans when I put in a new radiator a couple of years ago even though both original fans were working fine. I just didn't want to mess with them in the future - and I was there. I have never had a heat problem with the fans since I did that rewiring modification. When I bought car 1 in 1982, I had nothing but heat and fan malfunction because of the OEM circuits. I also wired the fans to run continuously when the AC is turned on. I felt the cycling, even if infrequent when the AC was turned on, was too noticeable and caused too much heat build up in the fans from the starting amps. My point is - OEM fans work fine if you can get the wiring fixed.

[Ras12]

Sounds like the best way to go is to check the voltage draw from my exiting fans first then either keep, rewire or upgrade them. In any case a bitsyncmaster upgraded electronic fan fail and solid state fan relay seem like a must!

I do not have a clamp on tester, just an analog HF probe meter and digital volt probe meter. Where is the best place to test the draw from? At the fans? At the relay?

Thanks for all the information.

[David T]

On 3 DeLoreans over 35 years, I rewired the OEM fans to each run on a separate relay and a separate 15amp circuit breaker with post and nut connections. I switched the power to come directly from the battery. I rebuilt 2 fans and replaced 2 on car 1 - a 90,000 mile car driven daily in Houston for nearly 8 years. No issues on car number 2 over 36,000 miles and on car 3 with 117,000 miles I replace both OEM fans with NOS fans when I put in a new radiator a couple of years ago even though both original fans were working fine. I just didn't want to mess with them in the future - and I was there. I have never had a heat problem with the fans since I did that rewiring modification. When I bought car 1 in 1982, I had nothing but heat and fan malfunction because of the OEM circuits. I also wired the fans to run continuously when the AC is turned on. I felt the cycling, even if infrequent when the AC was turned on, was too noticeable and caused too much heat build up in the fans from the starting amps. My point is - OEM fans work fine if you can get the wiring fixed.

Those 2 fans draw so much power when they kick on you can feel it in the gas pedal! With a Fanzilla at least they are staggered so it doesn't hit the electrical system so hard but I agree the wiring is marginal at best and that was when it was new! The system you describe is kind of how Lotus did it in later years, a fuse for each fan and they have 3 with a much heavier duty relay and heavier gauge wiring and connectors. If you are changing the radiator it is worthwhile to consider installing the Spall fans. They draw much less current and move as much (if not more!) air. Remember, over about 30 MPH you don't need the fans but if the A/C is running those fans are also running too! Even if the motor doesn't need them. Big load on the electrical system,;
1) the fans X2
2) the clutch for the compressor
3) the blower for the cabin
The compressor itself adds a lot of load onto that 130 HP motor. At idle when the alternator can't put out it's full output and the idle speed motor is trying to keep the motor from stalling! It's kind of amazing the whole system works as well as it does! BTW the compressor and the fans are supposed to cycle but that is only if everything is set up correctly. I see a lot of cars that don't cycle and that is very hard on that fan bypass. Potentially can also freeze up the evap coil.

[hmcelraft]

When the AC is turned on my compressor cycles fine but the fans do not cycle. The fan circuit stays cooler that way. I also built a fan shutdown sequencer so as not to stop both fans together and throw voltage spikes back into the system. On my car 1 - it still had the OEM Motorola alternator (new bearings once) and I never had a voltage issue in 90,000 miles. I find the newer alternators - especially the 130 amp I have now - are more than adequate.

[Elvis]

I'm still wondering how much better the "new" fans really are.

less current doesn't mean same pressure and airflow installed in the car.
it can't just be a better efficiency and more modern design.

problem with fans is - double power is only like 20% more airflow as
power rises ^3 with speed...and speed is airflow...
so to double airflow ~8 times the power is needed !

maybe a bit too much math in the morning, but I expect the new fans
are simply not as powerful as OEM but still powerful enough and putting
less stres on the electrical system.

I do have the possibility to have them measured at work, but I'd need
a radiator and fan set - stock and new ...and in the end nobody cares
as long as it works, and also nobody cares if it takes a few seconds more
to cool the engine down...

Good morning everybody :-)

[Bitsyncmaster]

I do have the possibility to have them measured at work, but I'd need
a radiator and fan set - stock and new ...and in the end nobody cares
as long as it works, and also nobody cares if it takes a few seconds more
to cool the engine down...

Good morning everybody :-)

I did some testing of fan airflow a few years back. My tests were with the fans mounted on the OEM radiator. You really need to have the AC condenser mounted also to get more accurate numbers. When air flow is restricted by the radiator and condenser the fan currents increase.

I agree that the higher power OEM fans have a little more airflow. But does that higher speed flow result in much more cooling, I don't know.

[BABIS]

for what it's worth, this is from DPNW website:

"These quality high performance fans utilize the latest state-of-the-art electric motors, each delivering 1248 cubic feet per minute (CFM) of air flow per the manufacturers data sheet while demanding only 7.0 amps maximum power each at full motor load. For comparison, the stock fans taken out of our personal car were measured at a total CFM of 1100 for BOTH fans"

http://www.delorean-parts.com/M erchant2/merchant.mvc?Store_Code=DPNW&Screen=PROD&Product_Code=K4001DP-A

[Bitsyncmaster]

"These quality high performance fans utilize the latest state-of-the-art electric motors, each delivering 1248 cubic feet per minute (CFM) of air flow per the manufacturers data sheet while demanding only 7.0 amps maximum power each at full motor load.

Measuring CFM is pretty tricky. You really need the same test setup done on all the units to get some relative accuracy of fan comparison.

I have some standard car relays that are marked on the case as 60 amp relays. You need to take manufacture specifications as questionable unless testing is proven via standards.

[DMCMW Dave]

Measuring CFM is pretty tricky. You really need the same test setup done on all the units to get some relative accuracy of fan comparison.
.

Exactly. Free-air CFM is nothing like CFM through a radiator/condenser. For a real measurement you need to measure them as-installed, which is somewhat difficult to do. MFR specs are certainly in free space.

[content22207_2]

In the bad old days, engine mounted radiator fans stopped spinning at higher RPM's, just using air flow from driving down the road to cool the radiator.

Any reason a DeLorean should be any different?

Bill Robertson
#5939

[Jonathan]

In the bad old days, engine mounted radiator fans stopped spinning at higher RPM's, just using air flow from driving down the road to cool the radiator.

Any reason a DeLorean should be any different?

Bill Robertson
#5939

My fans very rarely come on if I'm just out for a drive in the evening through the week. Now, granted, it doesn't get near as hot here as it might in the southern states, but unless I get stuck waiting at an intersection, I'll often go for the entire 1 hour drive and not have had them come on a single time (yet when they do, you know it, because I can see the change in my volt gauge while they're running).

[Bitsyncmaster]

Exactly. Free-air CFM is nothing like CFM through a radiator/condenser. For a real measurement you need to measure them as-installed, which is somewhat difficult to do. MFR specs are certainly in free space.

The most accurate way to get CFM would be to have the fans mounted and blowing up a very large "balloon". Then you would just time how long it takes to fill the 1000 cu/ft or larger "bag".

My air flow sensor uses a heated wire and computes the air flow by the cooling of the calibrated heated wire. That can show you the air flow but airflow is not consistent at the edges or center of the fan. So I compute the area of the hub and subtract that area from the area of the fan diameter. It gets very touchy where you measure. Hence, you need to test for comparisons with the same test setup. Real CFM numbers are hard to get.

[DMCMW Dave]

The most accurate way to get CFM would be to have the fans mounted and blowing up a very large "balloon". Then you would just time how long it takes to fill the 1000 cu/ft or larger "bag".

My air flow sensor uses a heated wire and computes the air flow by the cooling of the calibrated heated wire. That can show you the air flow but airflow is not consistent at the edges or center of the fan. So I compute the area of the hub and subtract that area from the area of the fan diameter. It gets very touchy where you measure. Hence, you need to test for comparisons with the same test setup. Real CFM numbers are hard to get.

My worry is that testing air flow with no resistance would not be accurate. Here's an electrical analogy - you can have an almost dead (high internal resistance) battery and the terminal voltage will still read 12 volts with no load. Put any load on it and it will drop to maybe 6 volts or less.

So you could have a fan with "thin" blades and a small motor that would move 600 CFM in free air, but drop to 200 CFM through a radiator (a load), whereas a fan with deeper blades and a larger motor would move close to the same air in both cases but would draw more current under load. Even your "large balloon" model would offer some resistance as it gets full.

There's no free lunch, it's physics. Electric motors are very efficient, typically. When I hear that a fan pulling 5 amps moves the same air through a resistance as a fan pulling 10 amps, I'm very skeptical. Electric motor engineering has not improved that much in the last 30 years. Maybe some due to better permanent magnets, but not a factor of 100%.

[Bitsyncmaster]

There's no free lunch, it's physics. Electric motors are very efficient, typically. When I hear that a fan pulling 5 amps moves the same air through a resistance as a fan pulling 10 amps, I'm very skeptical. Electric motor engineering has not improved that much in the last 30 years. Maybe some due to better permanent magnets, but not a factor of 100%.

I agree these fan motors are pretty much the same for efficiency. So your current draw is pretty much directly related to the output power. Only thing I'm not sure of is what the fan blade designs do the air flow. Many thin blades or a few wider blades.

Now there are better motors with cobalt magnets, wound with silver wire and ball bearings. You would need to spend big bucks for the motors and make your own shroud.

[David T]

Electric motor technology has improved a LOT in 30 years. The fan blades are also a more efficient design. We can argue over just how much better but bottom line is the newer fans are better. The proper way to measure the airflow is with an anemometer type gauge and then do the area calculation to get CFM. It isn't that hard but to do it while the car is moving gets trickier. The rad is fed by a pressure duct and is not very efficient if you are not moving. One trick is to simulate movement is by putting a fan in front of the car but it isn't accurate depending on how big a fan, how close, etc. Yes, manufacturer specs are usually in free air but they also give pressure drops so if you do know the pressure drop you can calculate what you can expect in the car. Now the hard part is measuring pressure drop. That measurement is not easy. You must also consider the OEM fan motors are not new so they cannot be as efficient as they were when they were new. Now you are comparing a 30 + year old fan with a brandy new one. Not a fair comparison.

[Elvis]

what we need to measure this accurately is the lab presented in this video:

http://mag.ebmpapst.com/de/einblicke/ebm-papsttv-eroeffnung-des-neuen-technikums-in-st-georgen_11002/

it's 50 feet next to my parking space and big enough to measure it with the car sitting in the lab, too :-)

I was asked if they could use my Delorean for the presentation, but then somebody decided to use that electrical
Beamer instead.

[Elvis]

if somebody wants to install two relays, too - here's the schematic:

43584

[Farrar]

On 3 DeLoreans over 35 years, I rewired the OEM fans to each run on a separate relay and a separate 15amp circuit breaker

This is what I did (after I too burned up a jumper wire and melted a relay socket). I used 20-amp auto-reset breakers. Stock fans were just fine after I made the change. (I also added "fan fail" light function to let me know when a breaker has tripped, but that's neither here nor there -- besides, someone else has probably come up with a more elegant solution.)

[Timebender]

Great thread. I recently took out my fan fail jumpers and put in a Fanzilla, which seems to be working well, and even does the timed shutdown which is kinda neat.
However now I've noticed when my fans come on, the fan fail light does as well. Is this a know thing with the Fanzilla or should I check to see if something is wrong?

[Bitsyncmaster]

Great thread. I recently took out my fan fail jumpers and put in a Fanzilla, which seems to be working well, and even does the timed shutdown which is kinda neat.
However now I've noticed when my fans come on, the fan fail light does as well. Is this a know thing with the Fanzilla or should I check to see if something is wrong?

When I had the Fanzilla the fan fail light would not come on. I think it just comes on if one of the fans is not working.

[David T]

When I had the Fanzilla the fan fail light would not come on. I think it just comes on if one of the fans is not working.

The fan light should NOT light if everything is working normally. In fact, one of the tests is to remove one of the fuses from the Fanzilla and you SHOULD see the light on steady. If the light is coming on at all it probably means you have a problem with one or both fans. Check the wiring connections to both of them and make sure the ground connections are clean and tight.

[Timebender]

Thanks guys. I know I hear at least one coming on. I'll take a look when I get a chance to see if both are running or not.

[Bitsyncmaster]

There's no free lunch, it's physics. Electric motors are very efficient, typically. When I hear that a fan pulling 5 amps moves the same air through a resistance as a fan pulling 10 amps, I'm very skeptical. Electric motor engineering has not improved that much in the last 30 years. Maybe some due to better permanent magnets, but not a factor of 100%.

I have a customer that has my electronic fused fan fail and he is seeing a fan fail light. He has the EU low power fans and he tested the fan current.

"I managed to check the fans today with engine running and they bounce between 2.8 and 3.1 amps"

I guess I have to make my minimum current check at 2 amps rather than 4 amps for the fan fail.

[Elvis]

I'd say he has another problem, 3 Amps for the work that needs to be done is not enough.

Maybe he has a resistance somewhere and therefore only this little current can flow - and your
warning light is right and warning him.

[Bitsyncmaster]

I'd say he has another problem, 3 Amps for the work that needs to be done is not enough.

Maybe he has a resistance somewhere and therefore only this little current can flow - and your
warning light is right and warning him.

I agree it sounds to low. He has not done a lot of driving but I asked if it keeps his engine and AC cool. He said yes.

[Tillsy]

I have a customer that has my electronic fused fan fail and he is seeing a fan fail light. He has the EU low power fans and he tested the fan current.

"I managed to check the fans today with engine running and they bounce between 2.8 and 3.1 amps"

I guess I have to make my minimum current check at 2 amps rather than 4 amps for the fan fail.

I still get the fan fail lights I told you about a few years ago - but my (NorthWest) fans are both spinning like crazy so no failure. I did record a video of the Christmas tree effect I get sometimes but never got around to sending it I don't think...

[Bitsyncmaster]

I'd say he has another problem, 3 Amps for the work that needs to be done is not enough.

Maybe he has a resistance somewhere and therefore only this little current can flow - and your
warning light is right and warning him.

Turns out Ed said his fans should be drawing 7.5 amps each.