[chevyrestore]

Hey everyone. Ive got a 59 chevy truck and installed an ez wiring harness a while back, ive just finished converting it to an electric fan and have a problem.

I have a FAN wire and a FAN POWER wire. I ran the FAN POWER wire into the fan, then out of the fan to ground. That way the fan runs with the key on and engine running. It works properly but heres the problem.

When I turn the key from ON to ACC the engine shuts off as it should, when I go from ON to OFF the engine stays running for 4-5 seconds and then shuts off (doesnt die out like a carb problem, shuts off like I just turned the key).

If I pull the FAN fuse and shut the engine off without the fuse in it shuts off properly, if I disconnect the FAN POWER wire from the fan and shut the engine off it shuts off properly.

My question is what should I do to fix this problem and what is this FAN wire for? I have 12v out of the FAN POWER wire on ACC and ON and 0v at OFF.

0v at FAN wire all the time.

Thanks everyone

[evh1963]

1 Wire For Fan Or 2
And What Is Resistance If 2 Wires
1 Wire System U Need To Install Suppressed Diode To Cancel Fan Return Voltage
THE 4-5 SECONDS IS BLEED OFF FROM THE FAN SPINNING RIGHT

[chevyrestore]

According to my schematic from the harness the FAN wire is supposed to go into the fan and then the fan to ground. It doesnt even show the FAN POWER wire. Where should the diode be placed? I have a diode on there going from the power going into the fan to the wire coming out of the fan going to ground.

[evh1963]

Fan Wire From Harness To Diode (ok Make Sure Diode Is Facing Right Way )diode To Fan Pos. Terminal. Power Will Only Go One Way Through It If Its Not Blown (check That Also) If Installed Right And Not Blown You Should Not Have Bleed Back To Harness
So If I Am Right If You Disconnect Fan Pos. Wire Off Fan Problem Is Gone Right If So It Is Definetly A Bleed Over From Fan Back Into Harness

[evh1963]

Does This Harness Have Fan Switch Wire If So U Should Have 2 Wires Switchwire Goes To Sending Unit Switch Like Gm At T-stat Housing Then At Switch Tolerance It Ignites Power Wire To Fan If Wires R Crossed This Is Problem

[chevyrestore]

Correct, thats what I was thinking, I reversed the diode just to see if it would fix the problem and it didnt.

I may have it wired wrong though. So heres how it should go?

FAN POWER WIRE (12v) to 1 terminal of diode, other terminal of diode to a spade terminal connection to fan, then fan out to ground.

Is that correct? Diode in line not jumped between 2 wires?

How its wired now is FAN POWER into fan, out of fan directly to ground, diode jumping both wires of fan (not inline).

Should I do it the first way or do I have it correct already?

[evh1963]

Diode Only On Pos Side Not In Between And Make Sure Diode Is Facing Right Way The Purpose Of A Diode Is So Current Only Flows One Way U Can Look @ Diode It Should Have A Line Around It (stripe)put Stripe Towards Harness I Will Find Pic To Help

[chevyrestore]

the diode will be able to handle the load from the fan? you want the diode inline correct?

[evh1963]

Look Up Pic Of Zener Diode

[evh1963]

Yes Inline Only On Positive Side . Do U Know Volt And Load Rating (amp)

[evh1963]

Did Diode Come With Fan Or Harness

[chevyrestore]

I have a few diodes here, the part number is 6070 A-160 1N5408

I just put one inline on the power side with the band on the harness end. Didnt work, I put the band on the fan side and it worked and shut off properly. If I added 2 or 3 in parallel would it handle the load better or what should I do?

[evh1963]

What Is Fan Grounded To Frame Or Batt And Points Or Hei Ignition

[evh1963]

Looking Up 1 Min

[chevyrestore]

diode was purchased online and this part number I got off a website saying to use this one. The fan is grounded to the radiator core support. Its an HEI ignition. Do I also need a relay to handle the load if the diode cant? Whats my option to avoid overheating if this diode fails?