Alright I know its been done before, but I have some personal wiring questions and am in need of suggestions. I am replacing my factory single fan on my LO3 with dual lt1 fans that I picked up cheap. I would like avoid using the factory coolant sensor as its half-way broken from header install. I can not write code for the fans because I still have the 8746 ecm. What I would like to do is have the fans on staggered temperatures both on and off, slightly lower than the factory 220º. I do not really want a manual only switch incase I forget or someone else drives, plus I like to keep the interior factory looking (however I might enjoy a manual switch in the engine bay for track duty). I have been using my A/c control as a fan switch lately, but in the summer I'm going to recharge it and use it. I would like some recommendations on what to use and keep the budget under $50 or so. Could I tap into the coolant gauge sensor in the drivers side for anything? Could I change the code for the AIR pump to run fans instead?

 

I'm using the Lx1 fans myself.

Bit of an older setup, MAF, but I don't see many options in your case other than what I am going to suggest...

I'm sorry I'm not up on the scheme for fan control with your ECM...it sounds similar to what I have though...one fan ECM controlled (primary) and the secondary controlled by a temp switch in the intake.

To me, the easiest thing to do is find a cooler fan temp switch for the intake, which would make that your primary fan, and the ECM control, since the temp turn-on would be higher, your secondary.

The only *GM* application I know that is "low" is one off of a later grand national. I'm not sure how low it is, if it's even lower than the 220* the ECM is going to command, but that info is probably on this board or over at gnttype.org I would imagine.

Another option for fan switches is to head to Napa, and ask to look at their Echlin catalog. That catalog is excellent, because it lists what thread the switch is, typically how it's wired, and the temperature rating. I wouldn't be too surprised if you could find other makes that used a lower fan temp switch than what GM did.

You'd have to change nothing from stock really, if your setup is like mine.

 

Does any one have any more pictures? I started cutting my old upper shroud and I don't think I'm doing a very good job. Also what tools did you guys use to cut with? I'm using an angle grinder but it isn't working well.

 

A two-fan setup from a 87-92 will bolt right up.

 

Next time I find an 87-92 two fan setup for $20 I'll pick it up. I bought a hayden 3647 fan control and installed. I found that with the lame-o 8746 ecm you can't do fan controls. The 3647 will work once I figure out why it has an electrical surge when connected to the smog pumps ignition wire. Its not very pretty yet, cause I haven't hid it. Also on those sensors can I extend the wires to move the sensor farther from the relay?

 

Look on Ebay. There are people (perrypam) selling the tops and bottom rails new, and someone's always got fans......

 

Yes you can extend the wires between the sensor(s) and the relay. That's what the relay is for, to reduce the length of the actual fan power wire(s).

If I were you I would wire that fan switch into the fuse panel. If the F-body panel is anything like mine, there are all kinds of open ones along the top if the panel that are unused.

Tapping into existing wires is a good way to cause problems.

 

My hayden 3647 relay is still too cold when I turn it as far clockwise as possible. How can I raise start the temperature? 175º is just too low, I'll never reach closed loop and gas is way too expensive for that.