The behavior of the fans (before you jumperd them to always run) sounds like the low speed fan is not working, only high-speed.
You'll find a lot of discussion about the low speed fan circuit if you search under Troubleshooting for 'low speed fan' or 'running hot'. Once you get the low-speed fan running normally, then judge whether you still have a cooling problem based on how high the temps go with fans operating as designed.
Allow me to paste in my previous post of dealing with the problem of low speed fan not turning on:
Quote:
But many people (myself included) have had problems where the lo-speed fans don't turn on, allowing the temp gauge to get up to the L range, then the high=speed fan kicks in and keeps the temps from increasing further. If that's your case its' possible the fan is your only problem.
Based on my recent experience here is my recommendations for anyone experiencing those symptoms with a Zetec. Most or all may apply for the Duratec too but can't vouch for it:
1. Check fan motor: Key in, engine off. Pull green relay in power dist. box under hood. Put a wire between contact 3 and 5 (see bottom of relay for contact #s.) Low-speed fan should run. If it does, go to step 3. If not, step 2.
2. Check lo-speed fan resistor: Bottom of fan shroud, driver side, facing rear of car. Pull connector. Put ohmmeter across two contacts, if open circuit, replace resistor. If good, test fan motor by applying twelve volts directly to the fan (or run A/C and see if fan comes on, or run engine with the ECT sensor connector unplugged). If both good, go to step 3.
3. Check engine coolant temp (ECT) sensor: Sticks straight up out of thermostat housing, under resonator. Pull connector, put ohmmeter across two contacts. If open circuit, or resistance jumps around, replace it. Maybe replace it anyway, it's only $16 and easy to replace.
4. Check wires to ECT sensor for cracking a la TSB 99M03: Pull back black covering and check wires for cracked insulation or bare wires showing. If damaged, replace fuel charge harness or have Ford do the TSB work for free if <100k.
Dont' skip 3 and 4, even if you replace the resistor in step 2. In my case, the resistor was bad and I still had to replace the wiring and ECT to get it back in order.
If all that fails, replace the low-speed fan relay, the tall green one, it's about $35.
