Electric fan conversion, fan will not turn on

[Tanner]

Hi Guys,

After a plethora of topics that came up when using the search function, i was unable to pin point an existing thread that related to my issue (although, several came close).

The breakdown,

a few weeks back, my car was overheating, the fan clutch did not turn on. The aux fan did not turn on either, even when pressing the a/c button. So i jimmy rigged the aux fan to come on manually(worked perfect). That held me over until i ordered an electric fan from Ireland Engineering and a 2-prong temp switch for an E30 318 (80c, pelican part to be exact. wrong switch? see below)

Pelican part purchased: 61-31-1-364-272-82-M323

Auxiliary Fan Switch 2-Prong (White Top) 82 Degrees, 318i (1984-85), 325/e/es/i/is/iC (thru 08/87), M3 (thru 02/87), E12 528i/530i, E28 5 Series all, E24 6 Series (09/82-08/86), E23 7 Series all,
Brand: FAE

So Saturday morning i did the following:

-removed fan clutch and fan (tossed it!)
-removed a/c condensor and aux fan
-replaced thermostat with a new 80c
-replaced 3-prong temp switch with 2-prong 82c temp switch. (used high speed wires from original temp switch harness and used spade connectors for new switch)
-installed IE electric fan(cut wires from aux fan, and spliced in new fan with factory a/c harness.)
new coolant, bled the system, etc...

the verdict:

temp gauge sits right in the middle while driving (very little fluctuation below & above middle mark during freeway driving)

when im at a red light or letting the car idle in front of my garage, the needle starts to creep up, and the fan refuses to turn on via the new temp switch.

so, my question(s)

1. incorrect temp switch?
2. does the 3rd wire im no longer using from the temp switch harness need to be spliced in or grounded somewhere? i was under the impression that was the low-speed wire and no longer needed.
3. simple re-bleed all that is needed?


Thanks in advance, and if someone finds this same exact issue on here, please link me for future reference!

[Varinn]

Have you tried manually jumping the relay to feed power to the fan? I would start with a basic test like that.

You can also try using a small strand of wire to manually trigger the relay, poke it into the connector for the temp switch to simulate a closed circuit and listen for the relay click. Do this with the ignition on, engine off.

To test for power to the fan take a small 3" piece of say 12awg wire with a spade terminal on each end and drop it into sockets 36/87 on relay's K1 and K6 (DOUBLE CHECK THIS, GOING BY MEMORY). Your fan will run when you test it as you'll be bypassing the relay and feeding power straight through to the motor.

You say you've wired into the low speed circuit but it's possible you accidentally crossed it up and have either the temp switch or the fan on the high circuit and the other on low. By testing these you'll figure out if you've gotten something mixed up. If using the low speed circuit it's worth testing your resistor in front of the stock aux fan . There will be roughly 6ohms resistance across the terminals, if too high or no continuity found just replace it. It is a $15 part.

[Tanner]

Thanks for your response.

I have tested the relays for high and low. The low speed relay actually does not work. The high speed relay clicks and works. I have jumped the wires to make sure. And obviously the manual button works great.

Regarding the resistor: I've read that the resistor only is hooked up to the low speed setting, and has no relation to the high speed setting. But it is still wired up, only because i wanted to keep things simple with the factory harness and not mess anything up (how ironic).

Heres a concerning update:

While running the engine with the front of the car on jack stands, I slowly loosened the fan switch on the side of the radiator. A tiny dribble of coolant spat out, but that was it. I was able to completely remove the fan switch without any coolant pouring out while the engine was running. Seemed strange.

[jlevie]

The lack of coolant when you removed the thermo switch says that there is a large air bubble in the radiator. If the switch isn't covered by coolant it probably won't get hot enough to turn on the fan. Bleed the system and get the air out.

[Tanner]

Thanks, J. My radiator is original and every time i drain the coolant, i get black specks which I'm assuming are from the radiator. Time to get a new rad and water pump.

[jlevie]

Whatever the black speck are, they are everywhere in the cooling system. Flush the system before changing the radiator by:


1) Get the front of the car 1-2' in the air on jack-stands.

2) Drain the coolant, remove the thermostat, and set the heater controls for
full hot. O-ring sealed thermostats require you to make up a temporary
gasket, which can be made out of pasteboard.

3) Add flush compound and fill with plain water. Then run the engine at normal
temperature as specified by the flush manufacturer (usually about 15
minutes at operating temperature). In cooler weather it may be necessary to
block off some of the air into the radiator to decrease the warmup time.

4) Allow the engine to cool until you can place your hand on the cylinder head
w/o discomfort. Drain the system and refill with plain water.

5) Run the engine for 10-15 minutes or until temp is close to normal.

6) Repeat (4) and (5) until the water drained from the system is clear and
free of debris.

7) Fill with coolant. It is best to dilute aiitfreeze with distilled water.
Tap water contains disolved oxygen and may contain minerals. Either of
which will reduce the lifetime of the coolant.

Notes:

You don't absolutely need to remove the thermostat, but doing so will allow
continuous flow through the radiator and will also make draining & filling
faster and easier.

Always allow the engine to cool to the point that you can hold your hand on
the cylinder head without discomfort. That will prevent scalds from hot
coolant and prevent thermally shocking the head when you dump the coolant.

Filling the system with hot water makes the process go faster and keeps from
having to run the engine a lot in a cold condition (rich mixture).

A rusty cooling system needs an oxalic acid flush. Kits for that (containing
oxalic acid and soda for neutralizing the acid) used to be available, but
arent now. 8oz of oxalic acid and 4oz of soda will treat a 1-1/2 to 2-/12
gallon cooling system. The procedure is like the above with an extra step 4
where the soda is added before the series of fill/drains are done. Since
oxalic acid attacks aluminum (which is why you don't find those kits anymore),
only use that on a badly rusted cooling system and replace the radiator and
heater core after the flush is done.

And while changing the radiator and water pump also replace all of the cooling system hoses, the expansion tank, cap, and thermostat.