North American Turbocoupe Organization

Cooling Fan Circuit diagram
Huey866 Offline
Posting Freak
Anyone have a wiring diagram of the Cooling fans on an 87 TC? I have a single Derale 17" 2 speed fan in place of the dual fans. I've noticed that one of the wires gets extremely hot, like melting the weatherproofing off of the connector, can't touch the wire, hot. I'd like to double check my connections and wire in relays if necessary.

When running, the fan is pulling about 14amps on low speed, haven't tested the high speed setting yet. 14amps is what Derale states is the low speed amp draw, high side should be around 25 amps.

Are the fans switched on the positive side, or are they switched on the ground side?
87 TurboCoupe - silver, 137k, 5-speed, 3.73, 5 lug swap, MM... Evertything, 03 Cobra Brakes, Griggs Subframe connectors, Bo 1.5, Big Valves, massaged 79 turbo head, Essy Cam Gear, Boblog + Elbow, .63 T-3, Stinger Exhaust/FMIC

Currently dreaming about ball-bearings and Pimps

Jeff K Offline
Positive switched. The issue might be the 2 separate stock fans versus the single 2 speed fan. Stock, the main fan (pass side) runs if coolant temp exceeds around 212 F or AC on, and the other fan (driver side) runs if coolant temp reaches low 220 F range or is AC high side pressure exceeds 310 psi.

Your 2 speed fan is designed to have either the low speed winding OR high speed winding energized, not both windings energized at the same time. If you just wired your 2 speed fan to the pass side fan circuit for LOW speed and the driver side fan for HIGH speed, both fan windings on your 2 speed fan will be powered up under conditions that would run both stock fans. It is possible (likely??) that this could cause excessive amp draw and possibly damage the 2 speed fan.

You need a 40 amp SPDT relay to switch power between the low speed windings OR the high speed windings on the 2 speed fan.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
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