Thanks in advance for any help. I have a 1989 Formula 350, and neither of the fans turns on under any circumstance (air conditioning on, etc.) I have replaced the fan switch and connector, I checked the fuses, and I repalced the relay. I am stumped. Any help would be appreciated thanks.

 

I had the same problem, tried the same things with no luck. Turns out I had a broken wire

 

It was a big pain, but I checked all of the wires and none of them are messed up. I use an ohm meter so I'm pretty confident they're alright. If my coolant sensor isn't functioning then could that cause both (or at least one of them) to not function?

 

Have you checked voltage on the wires as well ?

With the key in the 'run' position, there should be +12v on the tan/white stripe wire. No power here would be a blown (I think its labeled C/H Fan fuse ?).

The heavy gauge orange wire should have +12v on it at all times (it's direct power from the battery)

If you ground the green/white wire, you should have +12v on the heavy gauge black/red stripe. If you ground the relay (key in 'run' position) and no +12v on the outbound wire to the fan, the relay is most likely bad.

Also, try a direct battery power jumper to the + side of the fan itself to see if maybe the fan(s) itself isn't toast.

 

Thanks Deadbird that's a great help. May you be rewarded in the afterlife. :hail:

 

Thank you sir and, if I am.. hopefully it will be with my car... and somebody finally finished it for me :sillylol: :sillylol:

 

I did the above test and found that the orange wire (direct voltage from the batter) had no power at all. I gave the orange wire 12 V from the battery and then ran the car, and walla! the fans worked fine. I located all of the orange wire I could (removing the wire covers) but I only could follow it until it dissapeared behind the engine and I could find no breaks (I tested resistance just in case it was broken inside the insulation). I am wondering if you might have any idea as to where the most likely spot it might have broken is, or at least where the wire runs around my engine compartment. Thanks. 89 Formula 350 TPI

 

To be honest, I couldn't tell you were they are exactly since it's been (what seems to be anyways..) forever since my relays were in the stock locations. I do know one is usually (the primary fan relay) on the pass side firewall. Maybe someone else could shed some light on that one for you. If I were to assume, I'd say in close proximity to the primary relay or with the cluster by the brake booster. That's the only to spots I know of for relays.

On an '88 harness (and on my '87) the orange wire not on the 20a fuse, right off the battery, powers the fan relays only. The 2nd fan is connected to this via a flat plug (lower left corner)



As you can see, mine aren't quite where they used to be (neither are a few other things as well... like my mind ).

If the orange wire is indeed broken inside the insulation, I'd guess it's before the wire splits since you say neither fan works but, that's just guessing on my part.

 

THANKS