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rewiring the fan relays?

johnek74panterajohnek74panteraMember
Hi all. I am beginning the project of installing a new radiator and going to two spal sucker fans. I, of course, wish to wire in two new relays for the fans. I have a 1974 "L" with OEM relays and wiring. I have read the excellent articles posted online, however am still at a loss as to the specifics of how to replace the OEM relays. I understand that the pinks coming from the fuse box are the existing power and understand that I can remove them. My question surrounds the balance of the wiring running into and out of the OEM relays. How do I go about tracing them to see what their functions are, or is that even necessary. Is it all redundant at that point and can be removed. I"m afraid to get in there and start removing wiring that I may need. Any and all advice is greatly appreciated.
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George PGeorge PAdmin.
Acquire a pair of Spal FRH relay harnesses. They come with fuse holders and a generous amount of wiring. They are available on Amazon dot com.



Referring to the above drawing, see where the pink wires attach to new relays? There's a splice somewhere in that circuit.

See the new heavy gauge power wires connecting between the ammeter & the ignition switch? That's one possible connection, you could connect directly to the battery positive terminal also.

Everything "to the right" of the fuse box and below the fuse box is new wiring, abandon the old stuff. I mounted the fuses in the front trunk, in the front of the trunk, just behind where the oem fuses were mounted. Mounting them in the front trunk keeps the wiring & relays out of the elements. That was my preference. The SPAL relays are sealed very well and could be mounted in the oem location if that's your preference.

Grounding the fan motors and the temp switch requires a bit of additional wiring and some crimp terminals.

-G
johnek74panterajohnek74panteraMember
I am extremely electrically challenged. You say, "everything to the right of the fuse box is new wiring" however the diagram shows the original Pink power wire coming out of the fuse box to terminal 86. I am going to run new power directly off of the battery (fused). Do I still include the original pink powers in the new relay circuit as shown in the diagram?


quote:
Originally posted by George P:
Acquire a pair of Spal FRH relay harnesses. They come with fuse holders and a generous amount of wiring. They are available on Amazon dot com.



Referring to the above drawing, see where the pink wires attach to new relays? There's a splice somewhere in that circuit.

See the new heavy gauge power wires connecting between the ammeter & the ignition switch? That's one possible connection, you could connect directly to the battery positive terminal also.

Everything "to the right" of the fuse box and below the fuse box is new wiring, abandon the old stuff. I mounted the fuses in the front trunk, in the front of the trunk, just behind where the oem fuses were mounted. Mounting them in the front trunk keeps the wiring & relays out of the elements. That was my preference. The SPAL relays are sealed very well and could be mounted in the oem location if that's your preference.

Grounding the fan motors and the temp switch requires a bit of additional wiring and some crimp terminals.

-G
George PGeorge PAdmin.
quote:
Originally posted by johnek74Pantera:

Do I still include the original pink powers in the new relay circuit as shown in the diagram?



I did. It was convenient, since the pink wires are already there. It saved me having to pull those new wires. The relays are a low current load so the gauge of the wire is not important and the power to the pink wires is switched off when the key is in the off position. Therefore when you turn the key off, the relays are positively de-energized, the relay contacts open, and the back-emf of the fan motors cannot provide power to the ignition. This is important. You don't want to repeat the mistakes of the OEM wiring.
Last edited by George P
J jb1490Member
quote:
Do I still include the original pink powers in the new relay circuit as shown in the diagram?

Yes. This will will allow the fans to turn off when the ignition switch is turned off.

quote:
I am going to run new power directly off of the battery (fused).

If you are still using an ammeter, when the fans turn on, the ammeter will show a charge equal to the current draw of the fans. This fan load will flow continuously through the ammeter until the fans shut off.

John
bosswrenchbosswrenchMember
Johnek, know that I am also electron-challenged. There's one simple li'l mod to stock OR aftermarket relays that anyone can do. MOUNT THE RELAYS in the 'inconvenient' wiring-down position instead of the factory wiring-up position!
The reason is simple- if you ever hit a big puddle or drive in actual rain or snow, thrown-up water will pool on top around the crimped edges of the relays when they face up. Relays are NOT water-proof, only water-resistant. The pooled water will work its way inside the relay, rusting and shorting stuff. I've disassembled quite a few stock fan relays and ALL were rusty inside. Note the relays can be opened and guts can be cleaned, restoring some to operating condition.
Do your work as necessary, then rotate the relays on their stock mount bolts so the connections face downward. Just a li'l maintenence/longevity tip that costs nothing but a minute's effort.
huskerhuskerMember
Unless there is a diode installed.

quote:
Originally posted by jb1490:
quote:
Do I still include the original pink powers in the new relay circuit as shown in the diagram?

Yes. This will will allow the fans to turn off when the ignition switch is turned off.

quote:
I am going to run new power directly off of the battery (fused).

If you are still using an ammeter, when the fans turn on, the ammeter will show a charge equal to the current draw of the fans. This fan load will flow continuously through the ammeter until the fans shut off.

John
J jb1490Member
quote:
Unless there is a diode installed.

No true. If a diode had been installed, the proper place for it would have been in the negative wire from the fan, which would have reduced the voltage to the fan by slightly over one volt.

A diode could be placed in any one (or all four) of the wires on the load side of any of the four fuses shown in George's diagram, or in the wires from the load side of the relays, or the negative wire from the fan. If placed in the fan wiring, the voltage to the fan would be reduced slightly. If placed in the relay coil circuit, it would slightly reduce the voltage to the relay's coil.

A diode is not needed with this circuit. If one is existing, it should be removed.

John
tsolotsoloMember
Since you have already decided to go with Spal fans and a new radiator you should strongly consider the Panter Electronics radiator fan controller as previously stated. Since you're admittedly electrically challenged this would be a wise way to go. Jon Hass will offer excellent technical support if you need it. His products come with clear instructions and are designed for and function properly in a Pantera. I have installed nearly all his products in my car and am very pleased.

Steve
larrywlarrywMember
I have installed George's relay upgrades to my fans and ignition circuits, going on five years now with no problems.
I'm a pretty good electrical plumber, but no electronic technician. The PE stuff is wonderfully engineered, I'm sure, but several notches above my comprehension. I'm going to stick with what I understand and am capable of fixing on the side of the road by myself with a test light and jumper wires.
Not to mention that the relays and wiring bits were pretty reasonably priced too.
panteradougpanteradougMember
quote:
Originally posted by larryw:
I have installed George's relay upgrades to my fans and ignition circuits, going on five years now with no problems.
I'm a pretty good electrical plumber, but no electronic technician. The PE stuff is wonderfully engineered, I'm sure, but several notches above my comprehension. I'm going to stick with what I understand and am capable of fixing on the side of the road by myself with a test light and jumper wires.
Not to mention that the relays and wiring bits were pretty reasonably priced too.


I can only speak for myself but I had so many relays added to the car that in effect I needed a new master wiring diagram.

There were so many, I couldn't remember what they were all for.

The car must be at least 20# lighter with reorganizing back to the original harness using the PE controllers?

Everyone blamed the original harness itself. There isn't any problem with it. It's the best part of the original electrical in the car.

The PE controllers enhance the original car harness and protect it.

If you want to continue with the Mickey Mouse electrical design of adding relays, on infanitum, it's your car, and a free country.

I remember the song, do you, "Who's the leader of the Club that's made for you and me? M-I-C-K-E-Y...M-O-U-S-E!".

I miss Annette. Cubby was cool too. Wink
panteradougpanteradougMember
quote:
Originally posted by larryw:
Doug, are you referring to your workmanship and results or mine?


I don't know of your workmanship or results so how can I criticize them?

I was referring to a plan of using relays as a solution to electrical issues. I'm not really a victim of that since I willingly partook in it but it is clear to me now it was not a solution to anything long term.
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