How do I install diodes to my radiator fans?

quote:

Originally posted by rcpantera:
I'm not very electrical but thought that this forum is so in the know that even I can be schooled into installing diodes for my 2 radiator fans. When the car is up to running temperature, and I turn the ignition key off, the engine continues to run and I need to ease the clutch out to kill the motor. This only happens when the car is hot. Some have told me to just go to Radio Shack and pick up some, or a diode and that will cut the power from continuing with the fans running. I looked through quite a few pages in the electrical forum, and I'm sure it has been addressed before but can't locate it. Can someone direct me to the site, or tell me how this is done? Thanks for your help!

The diodes are installed on the positive or power side of the wire that goes to each fan. Many of the large after market fans will continue to spin after the power is cut off and they act as a generator and keep feeding power back into the electrical system. The diode should have an arrow marked on it and that will be the direction of flow for the electrical current. You can also check the flow path with a volt/ohm meter.

I used a couple of diodes from an alternator in my system. I think you need to check on the power rating of the diodes before purchasing and installing them. You are going to need something that can take up to 14 volts DC and maybe about 15 amps.

I have two new diodes I purchased from Hall. I don't need to install them now & I will be willing to sell for half of the cost.

You can reach me at dave@damardirect.com

Thanks,
Indy Dave

Dont install diodes. Run change the wiring so that the fans run directly from the battery. Then supply the relays with power from the ignition. This will require new relays. This is the proper fix and results in not only no runon from the fans generating electricity, but also gives more voltage to the fans and reduces current through the ignition switch.

OK... First you dont want your fans to become generators..... A diode is a gate.. it lets current through, but not back.. SOBil is the expert here. but I'm plannin' my install of my fluidine and. I want to keep it as simple as possible.. The first fan draw power from the alternator output. The second fan will run when A thermostat gets to 180 or so...... will the thermoswitch be locaated in the radiator or block... I ain't shure yet. " It is better to kill your motor with the clutch than let it run on" You say it only does it when it is warmed up makes me think it may be a timing or low octane fuel....I'm ok with the Diodes.. But a relay will also cut the return ccurrent... A diode is solid state and a relay will be another mechanical switch that could fail... I watcch my gauges and flip a switch if I want my second fan to come on.....Bill

Check this out before you do anything.

http://mysite.verizon.net/vzesb3ri/panteraelectronics/id3.html

My recently installed Mariah fans run on for about 5-10 seconds. #4134 has two factory relays. So why do I still have run on?

The design of the factory relay connects one side of the contacts to the coil and that common terminal to the power lead. Because of this design, the fans must be connected to the ignition. Otherwise the fans would run with the key off.

If you install a different relay (you need one somewhere), you can attatch the fan throgh the contacts to the battery, then the coil of the relay to the temp sensor and to the ignition. This is the ONLY correct way to wire the fans. It does not add any extra relays or components to the system. All you need to do is change the relays to a commonly available item and add a couple of wires and fuses to the battery. The end result is no runon and faster turning fans.

I've just retired my diodes and installed the relays as shown in Georges suggested fan circuit rewiring diagram. I actually used three relays, one for each fan, all hung in the stock location. I picked up my feed power with an added #10 wire at the ammeter. I also added a supplemental #10 wire from the battery to the ammeter. Fans spin noticably faster.

I also figured out that my third fan never seemed to help much. It was wired backwards!


While I was at it I did the ignition and headlight relay mod too. Pretty easy really. routing the wires neatly was the hardest part.

Perhaps someone can refer you back to those diagram posts. I'm not too good at those link things.

Good luck

I have a problem with Georges diagram. It is probably me. It is probably that I can't follow instructions exactly.

I have the battery disconnected until I can get back to the car. Since I modified the fan and realy system when the ignition is off and the battery connected, I have a battery drain which kills the battery.

You can hear the relays klick on when the battery gets connected with the ignition switch off. I'm probably running the relays to an unswitched source but I can't look at the car for awhile.

I am probably just going to skip this entire step and go to the Pantera Electronics relay elimination kit and bring that entire mess into this century.

The problem with these cars, unless you have had the car from new and know it's history, is that other people have been into them and modified them.

The cooling systems are the #1 thing that got modified since so many had overheating problems.
Also, theoretically the L's follow the factory wiring diagrams. I'm not so sure about that. I personally have too many gremlins related to electrical issues to preach that.

The amount of toasted wires in my car is just astounding.

Maybe you should get one of these.
http://www3.telus.net/bc_triumph_registry/smoke.htm

Thanks Larry but I need a smoke evacuation kit and some type of medication to sooth the discomfort of having to breath the fumes inherent to the smoke.

I think this is the link to the relay diagrams. It was originally posted 3/3/08 under topic of "Headlights"
http://pantera.infopop.cc/eve/forums/a/tpc/f/7890077274...790008145#5790008145

I think SOBill told me stepping on the brake and holding until the car shut off will keep the fans from generating electricity backwards due to the brake light circuit.