Cool Modification - For Pusher Fans Only, Though

patrickt · #1 (**permalink**) 08-14-2010, 05:41 PM

If you have pusher fans, along with a hefty puller fan, you know the pushers don't really do much other than look cool. All my fans come on when the thermostatic switch in the lower radiator hose hits its point, because both the pushers and pullers are all wired together. The same is true with the toggle switch on the dash -- they all come on together with the toggle switch override. Plus, they are all handled by the same single relay. If you're stuck in traffic on a 100 degree day you do want all the fans on together, but for the most part, you only want your puller coming on. If the puller fan failed, the pushers would probably get you by. So, it only makes sense to modify the installation to get backup redundancy. After thinking it through, I decided I wanted the thermostatic switch to only turn on the puller fan, but I wanted the toggle switch to turn on all the fans. Plus, I wanted the pusher fans on a completely different circuit so if the puller's relay failed the toggle switch would still allow the pushers to come on. The hardest part was finding the 12v DPST-NO Relay that would handle the amperage of the pusher fans. Omron Part #G7L-2A-BUBJ-CB-DC12 fit the bill, and it easily mounts on the driver's foot box, up near the firewall, next to the voltage regulator -- almost invisible. Then all you do is cut the blue wire on the fan relay that leads to the toggle switch, cut the red wire to the pusher fans, and wire it all in. Here are some shots and a wiring diagram.

ERA Chas · #2 (**permalink**) 08-14-2010, 07:22 PM

Groannnnnn...
The eight track would have been better.

patrickt · #3 (**permalink**) 08-14-2010, 07:36 PM

It's a nice modification, if I do say so myself.

I think it should be the default installation format at ERA for cars having both the big puller and the dual pushers.

ERA Chas · #4 (**permalink**) 08-14-2010, 08:10 PM

Quote:

Originally Posted by patrickt

It's a nice modification, if I do say so myself.

I think it should be the default installation format at ERA for cars having both the big puller and the dual pushers.

-And you will be the only one to say so. I'm concerned about that large, swollen object on your shoulders.

1985-puller fan, dash toggle plus 200 degree t'stat switch.
1993-pusher fans, dash toggle.

Any or all controlled by t'stat and DRIVER.

I'm SURE that Bob is losing sleep about his job security right this very minute...

patrickt · #5 (**permalink**) 08-14-2010, 08:15 PM

I like the single toggle switch. Remember, it's important to simplify your life. I think you need a vacation, Chas. Maybe a few days on the coast?

patrickt · #6 (**permalink**) 08-14-2010, 08:40 PM

... and, when would you ever want to run your pusher fans without having your puller fan on as well anyway?

henrik · #7 (**permalink**) 08-15-2010, 11:37 AM

Well, I have two

1) One is the standard for manual override of the pull...
2) Two is for manual on/off for the "show off" front fans - even with engine silent

I wanted two - I have two...

patrickt · #8 (**permalink**) 08-15-2010, 11:44 AM

Quote:

Originally Posted by henrik

Well, I have two

1) One is the standard for manual override of the pull...
2) Two is for manual on/off for the "show off" front fans - even with engine silent

I wanted two - I have two...

Yes, I thought of the "show off" factor. But, after carefully weighing the comparative impact, I decided that, on the few times that I would be showing off the pusher fans, it would be OK to have the puller running as well.

Mostly I want to better understand why Chas. doesn't want his puller fans running when he checks his timing. It's either a safety factor, a vision factor, or he quickly made up a bogus answer and is now stuck with it.

REDSC400 · #9 (**permalink**) 08-17-2010, 01:09 PM

I find this an interesting thread. ERA375 has both pushers and pullers. I shall explain why i have them wired totally separately on two totally separate circuits and switches. The puller is on the standard ERA circuit and two way switch. The pushers are on another circuit, using its own relay and similar switch however a simple Lucas On/Off switch.

The reason for the dual paths is that I wanted the fans to be in a high availability configuration sharing nothing so there is no single point of failure. There was an occasion back in 2003 where my thermostat switch somehow began failing. So that was the reason for the totally separate configuration. With the engine running I cannot hear if the puller is on or off (or the pullers for that matter).

None the less, I do applaud the approach of the author. Nice work.

patrickt · #10 (**permalink**) 08-17-2010, 01:20 PM

Quote:

Originally Posted by REDSC400

None the less, I do applaud the approach of the author. Nice work.

Well, thank you very much.

I'm tempted to throw that in the face of ERAChas, but out of respect and courtesy to our moderators, I won't.

henrik · #11 (**permalink**) 08-17-2010, 04:33 PM

Quote:

Originally Posted by patrickt

Well, thank you very much.

I'm tempted to throw that in the face of ERAChas, but out of respect and courtesy to our moderators, I won't.

You just did... and you know it

spf645 · #12 (**permalink**) 11-02-2013, 09:08 PM

Think I've got this one figured out.... You 2 have to be best of friends, (maybe brothers) just picking... I've read great advice given by each of you on questions ask on this forum.

My idea is the best, pride. My color, mine is fastest..
All makes for good reading.

My pockets aren't deep enought to get much into this competition, but couldn't help from stirring the pot a little.

Looking forward to reading more input (ideas) from you guys.
Thanks
645

patrickt · #13 (**permalink**) 11-03-2013, 06:27 AM

After this thread was posted, I split the circuits on the fans so the main puller is fed by an auto-reset circuit breaker and the pushers are protected with a separate in-line blade fuse. The two circuits now do not share the same fused feed. I never liked the "single point of failure" with the one glass fuse feeding all the fans. That was such a trivial mod that it didn't even warrant a new thread with detailed pics.

cycleguy55 · #14 (**permalink**) 07-24-2017, 04:56 PM

Quote:

Originally Posted by patrickt

After this thread was posted, I split the circuits on the fans so the main puller is fed by an auto-reset circuit breaker and the pushers are protected with a separate in-line blade fuse. The two circuits now do not share the same fused feed. I never liked the "single point of failure" with the one glass fuse feeding all the fans. That was such a trivial mod that it didn't even warrant a new thread with detailed pics.

I'm not currently running pusher fans, though I've certainly thought about adding them - mostly for the 'cool' factor. BTW, I'd wire them on their own circuit - with their own dash switch.

Regardless, after experiencing a relay failure on my puller fans (along with a scary high coolant temperature!!), the fix included a circuit breaker as well as a pair of relays in parallel. Each of those relays is rated to handle the full load, but I now have redundancy should one of them ever fail. And yes, I realize that, given those relays are sharing the load Murphy's Law says they'll never fail. I'm okay with that.