Adding electric fans to antique car

[Vetteman61]

Hello all,

I have a '71 Pontiac station wagon. A while back I sent my POA to be reconfigured for 134, changed to a parallel flow condenser and added a Pro 6 Ten compressor. The car would run hot (455 bored .60 may be the problem) when the A/C was turned on, but never ran hot otherwise. I would like to change the mechanical fan on the engine to an electric puller fan. I'll make my own shroud. I believe the correct operation of this fan should be that it comes on only when a particular temperature has been reached. I would also like to add a pusher fan in front of the rad/condenser. I believe the operation of this fan should be that it comes on any time the A/C is turned on. This car, of course, has no computer.

Is my assessment of when the how and when the fans should operate correct? I am unaware of how to wire and make this setup operational and would appreciate instruction. Here is a small picture to help visualize my desired physical setup.

Thank you,
Brandon

https://static1.pt-content.com/images/pt/2016/09/29660267171_0178f67379_b-1.jpg

[1989GTA]

There are stand alone controllers for the fans that will do what you want. One is the Derale 16795. If the A/C is selected the fans will come on for example. Actually with the car you have I do not see why you cannot run dual puller fans. That would be better IMHO. Or just one large fan if it covers a good portion of the radiator. Fan shrouds of course with either set up.

[andrewb70]

There are stand alone controllers for the fans that will do what you want. One is the Derale 16795. If the A/C is selected the fans will come on for example. Actually with the car you have I do not see why you cannot run dual puller fans. That would be better IMHO. Or just one large fan if it covers a good portion of the radiator. Fan shrouds of course with either set up.

That's what I recommended to him as well on the post he made on ls1tech...LOL

Andrew

[Vetteman61]

Thanks for the replies. I've gotten a lot of conflicting advice so I'm still up in the air on some areas. I definitely want a puller fan(s) and since a big part of my problem is cooling at idle, I believe a pusher fan on the intake side of the condenser would be a good idea, but I'm also considering if a pusher fan would be necessary. I'm also trying to determine if one large puller fan or two smaller (but large) fans would be best. It seems that the less moving parts the better for longevity. I would prefer to stay with parts that are easily replaced if they fail, like simple relays that are able to be purchased at any parts store or if I use a controller, one that is more readily available than a single product that, if it failed, would be difficult to replace if the model has been discontinued.




Brandon

[andrewb70]

Brandon,

The advice you got here and on LS1tech is actually pretty consistent. Everyone said don't use a pusher fan. Everyone said use the biggest OEM style fans you can fit, either a large single or smaller twins, this will depend on the size of your radiator. Everyone said that the load on the electrical system is substantial with big fans and there are different ways to address it. Some have said use a PWM module which simplifies things and offers high current capability and A/C activation. Others suggested taking a more simplistic approach with thermal switches and multiple relays. I favor the PWM approach because it eliminates the large draw on the electrical system when the fans come on...

Andrew

[H2Ogbodies]

What kind of wagon? A Tempest/safari wagon? You should have plenty of room for a late model style puller fan. I'd suggest running a Motorcraft dual speed fan-and keep it simple by using a multi-speed fan control system. I vote for OEM vs aftermarket every time for fans due to durability, you will want to think about a charging system upgrade-what upgrades to the stock setup have you already done? Do not use a pusher fan-you will only create a restriction in front of the radiator. I run a 3-speed resistor control harness using a 4-gang relay control bank and (2) GM style temp switches which eliminates the voltage spiking issues associated with running a high powered fan and relay activations for each speed-including high speed override for when the AC is on. This way, all components are easily replaced at any GM dealer or parts store-therefore no worries about failure prone PWM control units down the road only to find out it been re-designed, recalled or dis-continued. I've got installed and operating details/pics if you need more info-just lemme know!

[MonzaRacer]

Ikept a 10.5 to 1 402 bbc cool with a 91 Cavalier fan and shroud on factory style 3 row Monte Carlo/Chevelle copper and brass rad, never over heated, fans were controled by a Chrylser spec two prong sending uning that grounded through a wire under the valve cover bolt. My fans would kick on for few minutes after shut down and all I used were the 80's-90's oval GM fan relays(was told they would handle 70 amp surge and continuous 40 amp loads and at the time the junkyards were full of them. Had deal with local junkyard , take a box and side cuts and cut them out of cars that already had engines and trans pulled and were mostly stripped under hood. Usually paid $10-$15 a box with pigtails also pulled GM junction blocks. Rune a fused 8-10 gauge wire to them and have plenty of places pull battery load off of.
Used similar set ups on AC equipt cars, only difference is you set the system up to run fans all time if AC is on. I have used those dial type with the sensing bulb with great luck, let them control the relay and buy the knobs from Radio Shack. I keep seeing all these expensive controllers and so far the only one I have used was those adjustable ones with sensing bulb. But that of regular specific calibrated sending units, I know MSD and few others used to sell them.

[Dark Pursuit]

since your problem is only with a/c on at idle, a pusher fan should be sufficient to overcome your issue. Oem mechanical fans are very good air movers . You can wire the fan from a relay and control power from your a/c binary switch power. Fan will turn on only when a/c is turned on.

[keith4909]

I cutdown a 94 tbird fan assembly and wired it with a kit from hollister road company. The fan is two speed and about 120.00 new. I've never been a fan of buying the aftermarket stuff. Oem is bullet proof reliable. It also keeps my 474ci cool

[H2Ogbodies]

since your problem is only with a/c on at idle, a pusher fan should be sufficient to overcome your issue. Oem mechanical fans are very good air movers . You can wire the fan from a relay and control power from your a/c binary switch power. Fan will turn on only when a/c is turned on.

Pusher fans block airflow @ higher speeds so it's better to just use the largest puller fan you can fit and do away with a pusher fan idea entirely.

[H2Ogbodies]

I didn't see in any of the posts....so we have radiator fin dimensions and depth from the fins to the nearest accessory drive pulley or bolt head, etc.....? Can't suggest a fan unless we know hat.

[Later-A-body]

I agree with the OEM vs aftermarket fan idea. I will make a specific suggestion if it makes it easier. Go to your local wrecking yard and find either a Lincoln Mark VIII single 18" fan, or a Taurus/Sable 16" single fan. Both of these are VERY popular swaps that are well documented all over the internet. I have had both of these units in my GA. Both work great. I went to the Lincoln fan when I swapped to the LS. This fan is extremely powerful and will cost you no more than $40-$50. The Taurus fans are cheaper. The Taurus fan will probably fit inside your existing shroud. The Lincoln fan might need some trimming. Run a fan controller or a thermal switch so the fan comes on automatically, but make sure you run a robust relay to handle these fans as they do spike voltage on start-up. I run two 75 amp relays, one for each speed as overkill. You will want a more powerful alternator as well.

[andrewb70]

The OP hasn't logged on in about 6 weeks. I doubt he really cares...LOL

Andrew

[H2Ogbodies]

Well if the OP has the room, this dual 14" fan assembly moves approx. 6000 CFM max and measures 32x18x6.5 inches if the mounting ears are trimmed off. This fan is controlled by one of my progressive 3-speed conversion harnesses which among others things eliminates high inrush currents-and this is the only relay powered harness that operates in this fashion.

As stated before, go with the biggest fan assembly you can possibly fit!