Auxiliary Fan Controls / Wiring Question

#1

Allright, finally got the auxiliary fan remounted after removing all of the A/C components in the car. My question for you is whether or not it should operate when I press the A/C button.

Currently the cooling system is out of the car, so the water temp sensor is disconnected. I thought I read somewhere that the water temp needs to be tripped in order to allow the auxiliary fan to be turned on (either by the A/C switch or by the thermostat). Can anyone verify this for me???

Along the same lines, can I poll everyone to describe how exactly they have their auxiliary fan wired in??? Thermostat control, A/C Button Control, Switch, Any combination of the above?

Thanks in advance

#2

I will soon be tackling the same deal about fan. AFAIK, the fan should turn on when AC button is engaged( something along the lines that it puts additional load on the engine – pump is belt driven….). You can test the aux fan to see if it works correctly (even think that we had a discussin here about it recently so do a search). I am still debating how to ‘engage’ the electric fan:

  1. Using AC button - it is already there
  2. using switch with: OFF, always ON, and controlled by temp switch

HTH,
Igor

#3

I recently removed all of the A/C components off my car and mounted the stock auxillary fan in front of the radiator where the condensor was mounted. I used 1"x1" aluminum angle stock to mount the fan using the stock bolts and mounting points. If anyone is interested I’ll take some pictures.

I figure with the condensor out of the way and the radiator fan shroud removed I will get more air flow than ever before. As for the switch, I am using the stock A/C switch to turn it on/off. The only time you should need it is when sitting still with the engine running…which isn’t too often, I hope!

#4

I recently removed my mechanical fan and permanently jumpered the electric fan on high-speed setting, bypassing the temp switch, directly into the cockpit. I actually wired it into the foglight switch so i just turn it on manually.
Works great.

#5

Kelly - Puller fan with adjustable thermostat, wired to battery. Sensor mounted near upper radiator hose. Let me know if you want me to e-mail pictures.
Ed

#6

here is a writeup for an e36 - e30 is very similar
http://www.bimmerwerkz.com/forum/upgrades-performance/diy-fan-mod-understeer-30441.html

#7

screwynewy wrote:

[quote]I recently removed all of the A/C components off my car and mounted the stock auxillary fan in front of the radiator where the condensor was mounted. I used 1"x1" aluminum angle stock to mount the fan using the stock bolts and mounting points. If anyone is interested I’ll take some pictures.

I figure with the condensor out of the way and the radiator fan shroud removed I will get more air flow than ever before. As for the switch, I am using the stock A/C switch to turn it on/off. The only time you should need it is when sitting still with the engine running…which isn’t too often, I hope![/quote]

Screwy, did you know that there’s a set of brackets (about $12) that are made to mount the aux fax if you remove the condenser?

Brackets to mount aux fan

#8

sharkd wrote:

[quote]screwynewy wrote:

[quote]I recently removed all of the A/C components off my car and mounted the stock auxillary fan in front of the radiator where the condensor was mounted. I used 1"x1" aluminum angle stock to mount the fan using the stock bolts and mounting points. If anyone is interested I’ll take some pictures.

I figure with the condensor out of the way and the radiator fan shroud removed I will get more air flow than ever before. As for the switch, I am using the stock A/C switch to turn it on/off. The only time you should need it is when sitting still with the engine running…which isn’t too often, I hope![/quote]

Screwy, did you know that there’s a set of brackets (about $12) that are made to mount the aux fax if you remove the condenser?

Brackets to mount aux fan[/quote]

Well, that would have saved me an hour or so fabbing up mine. Good news is that mine where free since I already had the aluminum angle stock lying around. I’m sure mine doesn’t look as nice but it works great.

  • Ken
#9

Ed,

Please send some pictures when you get a chance. I finally got the cooling system back together with the opportunity to test it out. The auxiliary fan isn’t working now hooked up to the OEM wiring (off the thermostat switch and/or the A/C switch). Looks like I’ll have to re-wire it completely. My e-mail address is: kchildre@mindspring.com

Thanks again,

  • Kelly

edavidson wrote:

[quote]Kelly - Puller fan with adjustable thermostat, wired to battery. Sensor mounted near upper radiator hose. Let me know if you want me to e-mail pictures.
Ed[/quote]

#10

Kelly, I sent pics in a separate e-mail. Interestingly, I couldn’t get a hot signal from the old harness either, so I just ran new wires directly from the A/C switch.
Ed

#11

I am not completely sure if I understand what you are describing about not getting the hot signal, so this might be a bit off…
When AC button is pressed-in, one of the three horizontal sliders that controls vents has to be opened (at least slightly), in order for aux fan (and AC in the car that has it) to engage. Meaning, if you start with all three sliders in the left most position, and press-in AC button nothing will happen. Now, just slightly open one of the sliders (push it towards the right, i.e pass side) – AC button should illuminate and aux fan should be spinning.
HTH,
Igor

#12

I am not completely sure if I understand what you are describing about not getting the hot signal, so this might be a bit off…
When AC button is pressed-in, one of the three horizontal sliders that controls vents has to be opened (at least slightly), in order for aux fan (and AC in the car that has it) to engage. Meaning, if you start with all three sliders in the left most position, and press-in AC button nothing will happen. Now, just slightly open one of the sliders (push it towards the right, i.e pass side) – AC button should illuminate and aux fan should be spinning.
HTH,
Igor

#13

Igor - I wasn’t getting 12V at the original wire bundle for the condenser fan. I believe I had at least one slider moved, and I was getting activity from the A/C switch because I could hear the interior fan kick on at low speed. Anyway, it’s hard-wired up and I am happy with it - but it may have been the sliders. :pinch:

Ed

#14

Igor wrote:

[quote]I am not completely sure if I understand what you are describing about not getting the hot signal, so this might be a bit off…
When AC button is pressed-in, one of the three horizontal sliders that controls vents has to be opened (at least slightly), in order for aux fan (and AC in the car that has it) to engage. Meaning, if you start with all three sliders in the left most position, and press-in AC button nothing will happen. Now, just slightly open one of the sliders (push it towards the right, i.e pass side) – AC button should illuminate and aux fan should be spinning.
HTH,
Igor[/quote]

Igor,

Thanks for the help. I did try it with the vents open and the HVAC fan running. In fact the A/C light does iluminate, just no fan. Just curious, but regardless of the A/C switch, aren’t these fans tied directly to a temp. switch also??? If so, typically when should/do they kick in on the water temp gauge. My car tends to run at 11:00ish on the water temp gauge, moving up to 12:00 when idling.

#15

kchildre wrote:
quote]
Igor,

Thanks for the help. I did try it with the vents open and the HVAC fan running. In fact the A/C light does iluminate, just no fan. Just curious, but regardless of the A/C switch, aren’t these fans tied directly to a temp. switch also??? If so, typically when should/do they kick in on the water temp gauge. My car tends to run at 11:00ish on the water temp gauge, moving up to 12:00 when idling.[/quote]

The thermostat usually opens at around 80C (well, depending which t-stat you have installed so it can be below or above this temp). Anyways at least theoretically, t-stat should open when engine reaches proper operating temp - gauge needle should be around mid point. Aux fan kicks in either when AC is turned on (low speed), or when radiator mounted switch(es) detect hot temps (then they close). Low aux fan speed kicks in (assuming you didn’t change switches) at around 91C and high speed kicks in at 99C (IIRC). Now that’s pretty hot – water usually boils at around 100C.
I am not sure why your fan doesn’t kick in when AC (and slider) are engaged. Common failure point is resistor mounted on the aux fan itself.
Other failure modes for aux fan can be either bad radiator mounted switches, relays, fuses, and even t-stat (if it doesn’t allow water (coolant) to bypass the radiator, the radiator mounted switches will never detect hotter temps).

HTH,
Igor

#16

Igor wrote:
…Common failure point is resistor mounted on the aux fan itself.
Other failure modes for aux fan can be either bad radiator mounted switches, relays, fuses, and even t-stat (if it doesn’t allow water (coolant) to bypass the radiator, the radiator mounted switches will never detect hotter temps).
[/quote]

Igor,
Thanks again for the troubleshooting help. I’ll check the easy stuff (fuses) and take a look at the relay. Just curoius, but if the resistor in the fan is gone then the fan will not operate period right??? Also, what would be some other signs if the thermostat is failing??? Would the fact that the car seems to run "cool" under normally operating conditions indicate any problems along those lines?

#17

kchildre wrote:

[quote]Igor wrote:
Just curoius, but if the resistor in the fan is gone then the fan will not operate period right??? [/quote]

I think so. You can test the aux fan by jumpering wires at the temp switch on the radiator. Also, you can test the resistor (on the aux fan) with the ohmmeter - IIRC it should be around 6 Ohms.

[quote]
Also, what would be some other signs if the thermostat is failing??? Would the fact that the car seems to run "cool" under normally operating conditions indicate any problems along those lines?[/quote]

It’s tough to say but one possibility is that thermostat is bad. They usually fail in the “open� position, meaning that the coolant is always allowed to circulate throughout whole system. When this happened to me, dash temp gauge was always showing around 1/4 - 3/8 (it never got to half mark). It’s easy to test – with engine cool, remove thermostat and look at it (it should be in closed position). Also, you can put it in a pan filled with water, and warm it up on a kitchen-stove burner. Properly functioning t-stat should open when pre set temp is reached ( around 80c, so definitely before water boils). Clear this with wife first, I got in trouble for using good pan. In case that you never seen difference between open and closed t-stat, don’t worry as it will be clear once you see it.
HTH,
Igor

#18

Kelly,

Let me know if your fan is a dud. I’ll sell you mine - cheap.

Ed :laugh: