High speed elec fan doesn't come on

[Das Delfin]

What's up guys. My high speed fan doesn't work. I have an '87 with the dual switch on the drivers side of the radiator. When I jump pins 1 to 2 (the low speed) it comes on fine, but when I jump pins 1 to 3 (high) it doesn't come on. In both instances I hear relays clicking in the fuse box. I replaced fuse 18 (high speed fuse) and swapped out the K6 relay just in case. No change.

It's getting dark now so tomorrow I'm going to look at the electrical connector at the fan. Anything else I should check out?

[MR E30 325is]

Just to clarify, is this an aftermarket fan?

[Das Delfin]

no, stock

[Kershaw]

Are you having over heating issues or why is this a problem? Doesn't the aux fan only come on when you're over heating or if the ac is on?

[AndrewBird]

Sounds like faulty wiring between the high speed relay and the fan. Try jumping the relay and see if it comes on.

[PKile]

+1 on faulty wiring. If the fan motor was bad, it wouldn't run on low speed either.

[MR E30 325is]

Are you having over heating issues or why is this a problem? Doesn't the aux fan only come on when you're over heating or if the ac is on?

You are correct, but he should still be able to jumper connections and turn it on manually. I wired up my aftermarket fan through this switch, using the stock wiring, resistor and all.

There is an in-line resistor (that's what 'controls' low and high speed)

Check the wiring right at the fan. There should be a long rectangular resistor on one of the wires (This is low speed). Check the other wire for a break/short.

[Das Delfin]

Sounds like faulty wiring between the high speed relay and the fan. Try jumping the relay and see if it comes on.

That's a good idea. I had just a minute to look at it today and unfortunately I didn't prep by learning the wire colors.

Are you having over heating issues or why is this a problem? Doesn't the aux fan only come on when you're over heating or if the ac is on?

why does it matter if my car works? Are you serious?

[Das Delfin]

ok. Anyway, I'm out here with a flashlight and a multimeter.

I've swapped fuses 3, 18, and 19. Everything that could be related is brand new. I'm using two different relays for K6 and both seem to be fine. When I jump the switch by the rad, they both click on.

When I jump the switch AND pins 30 and 87 (with the relay removed), still nothing happens. Pin 30 on K6 is hot at all times so I don't even have to jump the switch or have the car on... which makes it easier. So I did that and still nothing happens.

I got out the volt meter. When I ground pin 30 of K6 it shows battery voltage.. which is fantastic because it means my fuse box is good. I tried to check for continuity between 87 and ground since 87 goes directly to the high side of the fan and eventually grounds out.. and my meter wasn't showing continuity.

So my next step is checking out the fan wiring. Thankfully my front lip is off the car atm.

I've been reading more about it and there's an 80/88 C switch which is different than the 91/99 C switch. I'm going to replace the one in my car with an 80/88 C and hope I don't spill much coolant in the process :P this will make the aux fan function more alongside the mechanical fan and help in stop and go traffic and/or when it's 110 degrees out.

[Das Delfin]

well. Figured that shit out. It ended up being a loose connection. The wire coming from fuse 18 going to the fan starts off black/blue, then goes to a plug (C113) where it becomes red. The way they designed the plug means the black/blue wire is able to come undone separately from everything else, and that's just what happened. An hour of troubleshooting, opening up fuse boxes, checking everything multiple times over, finally ends with a halfway undone plug. It's right below the headlights and probably happened when I wired up ellipsoids last spring. I plugged it back in for now and may revisit it later with a better connector.

[MR E30 325is]

well. Figured that shit out. It ended up being a loose connection. The wire coming from fuse 18 going to the fan starts off black/blue, then goes to a plug (C113) where it becomes red. The way they designed the plug means the black/blue wire is able to come undone separately from everything else, and that's just what happened. An hour of troubleshooting, opening up fuse boxes, checking everything multiple times over, finally ends with a halfway undone plug. It's right below the headlights and probably happened when I wired up ellipsoids last spring. I plugged it back in for now and may revisit it later with a better connector.

Glad to know I was right on the money.

Good to hear you got it fixed.

[Das Delfin]

:up:

[htseng]

I agree that you get a sense of satisfaction in getting things to work the way they were designed. I had
Just recently replaced the low speed resistor and its nice to see that temp gauge not creep up any further. Not that it ever over heated. But now if your resistor ever fails you know you have a back up high speed fan.


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