Cooling fan "fireside" chat...

[Lava Speed 05]

So I have struggled with these fans since the harness started melting at the relay. Now the fans won't run unless I put a jumper wire between the power and the fan wire. So either the relay I bought a few weeks back is bad, or I'm wiring it wrong. I also pulled the headlights to clean the grounds which weren't clean, but not horribly corroded.

I have tried swapping the relay Red/BLK (power wire) with the GRN/BLK (fan wire) as well as swapping the BLU/WHT and BLK/WHT both of which go to the PCM.

I'm going to buy another relay tomorrow to see if the fans will turn on, but I'm at the point of desperation where I may just run some wires into the cabin and use a manual switch. My version of megasquirt does not have fan controls, but I can see it light up the Fans, but they do not power on.

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[twistedwankel]

So I have struggled with these fans since the harness started melting at the relay. Now the fans won't run unless I put a jumper wire between the power and the fan wire. So either the relay I bought a few weeks back is bad, or I'm wiring it wrong.

There must be an internal short in the relay to get that hot? Is your VOM showing an open close to the fans when the relay closes (you should hear a click)? Hold a 10amp fuse in the line and see if it blows.

Once I put a mounted pushbutton jumper switch in the engine compartment for racing only for one fan. I also used the washer reservoir to mist water on the intercooler while racing. Good luck.

[Lava Speed 05]

That's the third relay, factory one on the A/C was rusted and the post broke off when I tried cleaning it. I replaced both the condenser fan and A/C relay with an O'Reilly's part as close to stock replacement as I could find that plugged right in. After less than a week and popping a couple fuses it just decided to melt the wires. This relay I believe when I installed the fans instantly turned on when the key went to "On" before starting the engine, but now I can't get the fans to start unless I do a direct jump from the BLK/Red to the LT GRN/BLK wire.

I changed the ground point on the one fan to a separate chassis point and planned on doing the other fan to see if bad grounds caused the over heating, but now they're not running at all.

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[twistedwankel]

Would be a simple matter to hot wire each fan to see if the motors are still good. Not quite sure why that is a 30amp relay? Lot of juice for small motors and lights. Wonder if a PO messed with something for a stereo amp? I found a 60A fused connection coming off my + lead for a removed stereo once. Used cars:(

NAPA used to have better electrical parts than anyone. I found my 04 Mazda engine relays are actually Mitsubishi parts much cheaper. Just need the number off it to match.

This is one of those times you need a same year car to swap parts to test and save time and money.

[Lava Speed 05]

That relay is normally a 20A, but I read some where they are prone to failure and the fuses in the system for the Mazdaspeed are 30A. Figured I could run the 30A relay as it was the only four post relay I could find easily. Here is a picture of the factory relays.

I think the other issue is I'm running dual Spal fans off the same wire set, granted the factory system does run different motor winding off the same color but these draw slightly more than factory... ;-) Flyin Miata sells the hell out of these fans, but there are other Mazdaspeed guys that struggle with them apparently. The more complex four wire fan set up with four relays isn't making it any easier.

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[twistedwankel]

https://www.summitracing.com/parts/der-16749/reviews/

Matt I looked into this today while you are racing. Summit Racing sells those Spal fans so I read a few reviews. They can pull a lot of continuous amps which will melt wires and controllers. I found two guys had the same issue. "Short in the base the relays plug into." Check those first. Also your stock power wires are probably too small a gage for the amps those fans pull over time. The kits they sell includes the stouter wiring harness. I didn't see the Derale dual relay kit #16765 one guy mentioned as good.

Not knowing which fans you have so I looked at bigger cfm ones. Appears some only pull 13amps each which together would have exceeded your stock 20A relays. Most of these kits appear to come with single 40amp relays. Season's over. You have time to sort it out. A number of people said their Controllers won't hold up with continuous 23A draw either.

Probably why I don't mess with stock electrical/ECU systems since they banished the old plugin PROMs and swappable ECUs.

Doug

[Lava Speed 05]

That was my suspicion, I appreciate you for looking into it. I did run a switch last night with 12 gauge wire and it seems to have held up better and the wires were not getting as hot. I was thinking the same thing, that I need to just get/bypass all the factory wires.

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[Loren]

Now that you've found the problem, you should be able to run dedicated wiring, new relays, and trigger the relays from the wires that are currently triggering the stock relays. The fan switching wires that originate at your ECU should be unaffected by current overloads in the original wiring. Just find them and run them to your new, mo-betta relays with properly sized power wiring.