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I have an 86 firebird base with 305, but it’s been converted to Edelbrock carb and ecm delete. I couldn’t get the fan to work right so I wired one fan wire to ground and one wire directly to a switch, to inline fuse, and then to “bat” in my fuse box. Worked fine for a while but all the sudden I’m blowing the in line fuses, the acc fuse, the gauge fuse etc and cannot get the fan to turn on for more than half a second. Most of the knowledgeable people in the other threads said to wire the fan back to the old relay, but their relays don’t look like mine. I’m about to leave for college and I want to drive the car one last time! Please help. These are the relays I have:
If you're going to use a switch, you could ust wire a standalone relay system.and the relay power to soemthing on the car with keyed power... that way it will shut if whenever you turn off the key and you wont accidentaly leave it on and kill the battery.
As already stated, do not use the "Batt" Power Terminal on the front of your Fuse Panel.
It is only for Low-Amperage use.
The Electric Cooling Fan is a Medium to High Amperage Device.
The Electric Cooling Fan Relay is the Relay on the Firewall Bracket in your Images.
Reconnect the Original Electric Cooling Fan Wiring.
The Green Wire that you see at the Relay Connector must be Grounded to activate the Relay.
Get a 180 Degree Thermostatic Switch for that Green Wire.
The Electric Cooling Fan will now turn on automatically at 180 Degrees.
Last edited by vorteciroc; Aug 20, 2024 at 06:18 PM.
I hate to be mean about it, butt about the stuuuuupidest possible way to approach this, is to use a switch to directly control the fan motor the way you've got it. You're forcing all that fan motor current (upwards of 30 amps) to flow through all that wire and the switch. That's just wRong. It's no wonder fuses are blowing, things get hot, etc. You probably have some melted wires somewhere which is probably what's blowing the fuses.
Take all that crap out that you put in. Put the fan wiring back like it came. Its power should come from the blk/red wire coming off of the relay, and it should have a ground made of equally fat wire. (#10 would be about right) I'd recommend grounding it straight to the block, which is the electrically closest place to the batt and alt. By doing it that way, you avoid forcing the fan motor current through the ground straps connecting the chassis to the block.
Observe the wires at the relay. Looks to me like there's a "rust" color fusible link (hard batt to the relay with the FL for protection) coming off of that big fat red wire, the blk-red to the fan motor, brn which would be switched ignition such that the relay can only be operated when the key is On (looks like there's one wire bring that voltage in and another carrying it further along to some other destination), and grn/wht, which is the coil (control) for the relay. The factory's design allows the relay to be operated by whatever would ordinarily have grounded that grn/wht wire back when it worked right, which is to say, before all these "improvements". In various different versions of these cars (and hundreds of millions of others), the thing(s) that grounded that wire would have included the fan switch in the head, the ECM, a switch in the AC system that indicates somehow that the compressor is running (usually pressure in the high-side line), or some combination of those. With them all in parallel, any one of them that happened to determine at any time by whatever logic it uses, that the fan needs to run, can command it On.
Simplest thing you can do is, REMOVE all that crap you tell us you've junked up your car with; reconnect the original blk/red wire at the fan motor, and ground the other terminal of the motor, as described; and put a fan switch in the pass side head (your car might already have one of those). Hook up the grn/wht wire to that switch. The wire might also already be there if it hasn't been "improved" with dykes. The relay will then operate whenever the key is On and engine temp exceeds the switch's set point. If your car has a pressure switch in the smaller AC line, hook that up to that circuit also, with the grn/wht wire going to one terminal of that switch and its other terminal grounded. All of the grn/wht wire circuit can be small wire, as the current in that will only be what the relay coil draws, which is far less than 1 amp. Believe me when I tell you, you don't know better than all the engineers at every manufacturer of cars that use electric fans, how to optimize the fan circuit. Follow their lead.
If you just feel like you HAVE TO have a switch to turn the fan on manually based on whatever excuse you dream up, add a 3rd connection to the grn/wht wire circuit; run that to your switch; and ground the other switch terminal. If your switch has 3 terminals, run the grn/wht to the Common terminal, and ground the Normally Open (the one that isn't connected to Common when the switch is in the Off position, and becomes connected when you flip it to On).
The LEAST RELIABLE method of fan control is to do it solely by hand. This REQUIRES the intervention of a HUMAN, and as we all know, those things are the flakiest part of ANY control system. It's ALWAYS better to do it automatically; that way, you can't "forget", if someone else is driving they don't have to be told about it and then "remember" it, etc. etc. etc. Adding a manual switch as a backup isn't stuuuuuuupid the way that REQUIRING the human to flip it, would be; butt it's just not the least bit necessary or even particularly desirable if the car is built and wired properly.
Thank you all so much for the help, I know a little bit but this is the learner car. I’ve got the fan hot wired up just to move the car around a little bit should I have to, but will be ripping all of it out this summer when I come back and doing it right. Thanks again for the help and patience!
