cooling fans and 60 amp fuse

I have a 94 auto sc.

On the way to work last week, with the a/c on, the temp climbed to 195-200 at 5:30am for a 8 mile drive on the freeway. It normally runs at 180 under any condition. it got hotter, 210, on the way home at 6 in the afternoon with outside temps around 95. Got home and noticed that my fan wasn't coming on, and I know it should with the ac on. I utilized the search function on here and discovered a blown 60 amp fuse under the hood. I pulled the fuse to find the same thing I read about, a small spot around the fuse port was melted and one port was slightly pulled up and out of the bottom of the fuse box. I replaced the fuse to try that out, nope, instant pop.

I read that there can be a short in the puller fan motor. So I've got a new fan motor sitting here. I'm not sure if I should bypass the fuse box and run a separate line for the 60amp fan wire, or try to repair the fuse box itself. I haven't done either type of repair before, but I'm don't think it would be too difficult.

I'm able to make it to work w/o it getting too hot as long as I don't use the a/c. A credit to that big Griffin radiator.

Any suggestions?

I've seen some pretty distressed fuse boxes when looking at the bottom side. If one is injured/burnt, there may be others. And it might be as much about collective corrosion underneath as it is a too high draw across the fuse.

Point is you may be looking at replacing the entire box and cleaning up multiple wires/connections, but until you take it loose so you can see the extent of damage, you won't know.

fan activation

I read in a previous post some time back that if you disconnect the EEC temp sensor and turn the key to the "on" position, the low speed fan should turn on. Is that correct? If so, mine does not. Although the fans come on when I run the KOIO test.

Thoughts?

Actually, that test should be done with the engine running, not just key on.

I wound up getting two fuse boxes from non sc v6's at the local junkyard to practice on without screwing anything up on my increasingly tired daily driver. I've been driving back and forth to work still without using the ac with engine temps staying around 195 on the freeway. I'll take out the fuse box on my bird tomorrow and either repair the wire and box at the 60 amp fuse, or wire a 60 amp in-line fuse adjacent to the box on the firewall. I've also got a new puller fan motor I'll replace as well. I'll post up with the results.

After sweating my arse off today and being meticulous with everything, The fan motor still blew the fuse as soon as it came on. I replaced the puller fan motor with a new one, checked the wires at the fan, and they looked good. I pulled the battery and alternator off to have more room with the fuse box. The box was melted through at the 60amp fuse for the fan. The wire was burnt and brittle a quarter inch below the box.

I cut the bad wire, and connected good wire from a donor box and harness. Heat shrinked it and put the repaired wire and fuse connector in the old fuse box with a new 60amp fuse. Put a new alternator on, new puller fan motor, dabbed a little di-electric grease on the fittings for the fan & alternator. Burped the cooling system, hoped everything would be good, and fired it up.

As soon as I turned the ac on to signal the puller fan to come on, the 60 amp fuse popped. The pusher fan does come on. But that doesn't do me a lot of good. So, I know there is an issue somewhere, I just don't know where.

Bummer.

Where should I go from here?

On the assumption that circuit has shorted to ground, put an ohm meter on it, then start removing connectors.

Something overloaded the stock wiring causing it to melt at the box, so... I've seen examples of that, and it's never good news.

As well, if you have an EVTM for your car, start tracing...good luck.

KMT,

What is an EVTM?

And where do I connect the OHM meter? And what connectors do I start to unplug and what is it I'm looking for?

Excuse the questions if they seem simple. I can turn a wrench with no problem, but the electrical component, and wiring diagrams are a bit more complex for me, not from a lack of effort, as I'm not opposed to trying it or doing the work, but I don't understand the electrics as much as some others here do.

scskydivin said:

KMT,

What is an EVTM?

And where do I connect the OHM meter? And what connectors do I start to unplug and what is it I'm looking for?

Excuse the questions if they seem simple. I can turn a wrench with no problem, but the electrical component, and wiring diagrams are a bit more complex for me, not from a lack of effort, as I'm not opposed to trying it or doing the work, but I don't understand the electrics as much as some others here do.

Click to expand...

Good evening


The Electrical and Vacuum Troubleshooting Manual (EVTM) purpose is "To make troubleshooting easier by showing the electrical and vacuum circuits of the vehicles in a clear and simple fashion. With each circuit is a description of How the Circuit Works and some Troubleshooting Hints. A component Location charts lists components and references to pictures in the manual".

This is an extremely important technical source when in depth electrical and vacuum troubleshooting is required. Use the corresponding model year in conjunction with this forum to return your car back to service. Examples where they can be purchased are HELMS automotive library, EBAY, this forum (for sale section) and Thunderbird SC parts suppliers (SuperCoupe Performance, Thunderbird SC Shop).


Good Luck.

scskydivin said:

What is an EVTM?

And where do I connect the OHM meter? And what connectors do I start to unplug and what is it I'm looking for?

Click to expand...

Electrical and Vacuum Troubleshooting Manual (EVTM) - typically available off eBay for a decent price...get the one for your year SC. They are the electrical bible for our cars, and a must for the SC owner, in my opinion.

On the assumption the issue is after the fuse, I would start checking by removing the fuse for the fan, then confirming which is the hot side. Then connect the OHM meter to the other side and to the ground terminal screw for the EEC on the header panel, in front of the battery....it should show continuity/path to ground -- unplug both the puller and pusher fan connectors, at the fan, unplug the IRCM and remove the negative battery cable at the battery. See if you still have continuity at the meter.
- If not, then plug everything back in one by one until you do. That might shed light on at least which circuit/component to focus on.
- If you do, then you may or may not have actionable data and it's time to study the EVTM.

Unless you can spot an issue by eye, it comes down to trail/error.

These cars live and die by their electronics and grounds, so don't assume anything.

Excuse the questions if they seem simple.

Click to expand...

No problem. Good news is, most of the simple (and not so simple) questions have been answered here, so you might want to get into the habit of searching first, just so you don't have to wait for a reply (EVTM is a good example, I think).


Good luck.

Thanks for the advise guys. I'll try to get my hands on an EVTM manual.