FYI: I finally updated the parts list and fixed all the old torque central references. The excel file in the first post changed as well. A bit more progress on the car too:
For a couple months now my signature has referenced ?breaking it in, working out the bugs? I figured it?s about time I finally got around to documenting what I might have done different given the advantages of hindsight.
Wiring: cheats and redos: Fan Control via DC Control FK-35:
I tried to use existing Mazda relays to control the Volvo fan which aren?t rated for the load. I actually knew that already but I figured I could get away with it. Most specs I?ve seen on the Taurus fan are somewhere around 30A (amps) steady state and quite a bit more on startup. I assume the Volvo s80 fan I?m running is similar. Danzan was under the impression the H430 relays I had grabbed off my parts car were good for about 30A each. So the theory was that I could wire the signal coils in series so they?d both switch together and wire the power to the fan in parallel to load share.
Worked great? for about four months, until I was charging a canyon on a hot day. I pulled into the parking lot at the bottom and spontaneously overheated. Damn, no fan. It?s kinda funny that it did fine while I was still moving. After a little investigation here?s what I found:
Smoked both relays right at the power contactors. Oops, I?m assuming my setup was marginal and forcing it to turn on and off a bunch of times pushed it over the edge. This is why wiring insulation isn?t flammable anymore. If this was 50 year-old ride and I might have burned my car down. It?s no wonder Painless has done so well selling wiring redo kits for classic cars.
Moral of the story: You need at least a properly rated 75 amp relay for fan control if you?re going through the ECU. The more I think about it the more having a soft start option seems like a good idea. As such I threw down for the DC Control FK-35 setup.
It uses a temperature probe wedged into the fins of the radiator itself to continuously vary fan speed to a known temperature. The jumper pins attach the probe and allow different temperature settings. Seems like a slick unit but I?ll report back in once I have a little more time with it. I did find a nice spot to mount it on the fan shroud. This is just the test fit, I used the supplied mounting screws, disassembled all the crimp connectors and soldered/heat shrunk everything.
[Ed note: given the benefit of hindsight, a little more feedback on the FK-35 box follows?]
Joel - any positive or negative feedback on your DC Control variable speed fan controller? You're running this without AC, correct?
No AC yet, but I'm planning on it and did all the wiring required during my last downtime. Just need to get it plumbed.
As to the FK-35: I like it. The only real con I can see is the added cost vs. just running a big relay. I?ve been told that a good old fashioned 70 amp relay from radioshack is enough to have run ECU control if you want a simple brute force setup (stock relays are not) but this is certainly a heck of a lot more elegant.
Soft start works exactly like it?s supposed to so you never blast the fan with that big current hit up front. Jumpers for temperature adjustment are easy and work well. It?s just a simple clean solution that works.
I?ve had two issues in the two years I?ve been running this. The first was my fault when I was reassembling the car super late one night and managed to reverse power and ground. Don?t do that. It let out some SERIOUS magic smoke as it gave up the ghost. Still I was enough of a fan that I bought another. DCC even threw me a small discount because I only needed the FK-35 unit and not the full kit.
The second was more recent? this box itself started to misbehave (just randomly not turn on when temps clearly say it should have. At DCC?s request I sent it back for service and everything checked out correctly on their bench. Brian from DCC suggested I may have had a connection go bad so I?ll give all the terminals a going over with sandpaper before it goes back in. I still like the setup but until I?m sure it run problem free I can?t give it an unqualified thumbs up.