• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Need Help - wiring Automatic Cooling Fan

Share this page

CharlieCarpenter

CharlieCarpenter

Senior Member
Offline
I'm installing an electric cooling fan on my radiator. I have the thermo-switch installed to turn the fan on at 185 degrees. I need some help on how to wire it: The car is negative ground.
I need to run a wire to the power side of the thermo-switch that will give me juice only when the ignition is on, otherwise the fan will run until it cools all the way down draining the battery. Where should I run this wire from?
Many thanks
 
CharlieCarpenter said:
I'm installing an electric cooling fan on my radiator. I have the thermo-switch installed to turn the fan on at 185 degrees. I need some help on how to wire it: The car is negative ground.
I need to run a wire to the power side of the thermo-switch that will give me juice only when the ignition is on, otherwise the fan will run until it cools all the way down draining the battery. Where should I run this wire from?
Many thanks
Click to expand...
Try a blank terminal where all the green wires come out of the fuse box butI strongly recommend a relay instead of going straight from the fuse box to the thermostat control.
Patrick
 
Patrick: Do you mean just connect a additional wire to the fuse box along with the three other green wires? Regards relay?? Where would that go? Any fuses?

Sorry for dumb questions.
 
Charlie--

I opted to wire my electric fan with no thermostatic switch and to a SPST switch powered to always hot for two reasons:

1. This gives me the option of turning the fan on manually when I see that I am getting into a traffic situation and slowing the rate of rise when I am at 160-170 rather than having to wait until an auto switch would do it for me at 185.

2. It also gives me the option to leave the fan with the ignition is off and providing air circulation over the rad and engine even if I were stuck in some serious traffic jam and the temp was already and I chose to switch off the engine to avoid further overheating.

My fan is pretty loud and I would never walk away from the car with it on without knowing it. If you are still concerned you could wire a red light into the power circuit.
 
CharlieCarpenter said:
Patrick: Do you mean just connect a additional wire to the fuse box along with the three other green wires? Regards relay?? Where would that go? Any fuses?

Sorry for dumb questions.
Click to expand...
Not a dumb question! Maybe someone will post a wiring diagram here for you to see and or instructions. My car is all apart undergoing a frame-up restoration and I'm not quite ready to install the wiring harness which I would need to do to make a wiring diagram for you. I have an AC and electric fan and both use relays but I need to hook it back up to make a diagram.
Patrick
 
I have figured out the wiring diagram and I already have a "always hot" switch like Micheal suggests. My questions is simply where physically do I connect the "when ignition on" wire to? Does that make sense?

Thanks
 
Hi Charlie,
Personally, I'd connect to the fuse block where the white wires are. This is the switched hot un-fused side. Then put an appropriate inline fuse in for the fan. The reasoning for this is not to overtax the 35 amp fuse that feeds all the green wired components.
 
I have two 6-position fuse blocks on the firewall.

One block is hot all the time and I use it for things such as the auxiliary fan, horns, standard lighting, radio memory feed, 12 volt accessory plug and 3rd brake light.

The other block is hot only with ignition on and I use it for things such as wipers, turn signals, radio power, fuel pump 1 and fuel pump 2.

It is not original but that is the way I like to do things--separate circuits for each appliance as much as possible.
 
I simply bought the units at a marine store, got a bit ruthless with the wiring and started pulling circuits from the two standard fuse connections and ran them to the new ones listed.

I placed the blocks prominently on the front side of the firewall in the space vacated by the OD relays, etc. as I have a 5-speed, but if you wanted to keep an original appearance you could mount them beneath the dash somewhere, even keeping the original fuses and having (dummy)harness and wires run up to them and do all the real stuff in a concealed spot.

No doubt my attitude may come from having spent 30 years living or cruising on board a boat which had perhaps 40 DC circuits and 30 AC circuits, but I feel that fuses should provide protection for each circuit/appliance as much as possible and we get that by having as many separate and dedicated lines as possible.

I'll try to send you some photos Charlie.
 
Back
Top