Air-con aux fan (new question)

Thu Apr 20, 2006 9:40 pm

Ive got an air-con fan to use with my M50 lump, but what are the proper air ducts that I need to use? Ive been through some pages on realoem and found a few options but not certain.

6 and 7 here
http://www.realoem.com/bmw/showparts.do ... g=51&fg=75

4 and 5 here
http://www.realoem.com/bmw/showparts.do ... g=41&fg=10

Do I need all of this?
Anyone with an aircon car know exactly what parts are what?
Thanks in advance

Thu Apr 20, 2006 10:42 pm

I think you only need part 1 on the first one, and i think it's the same on all models

Thu Apr 20, 2006 10:44 pm

Had to remove that to get the fan in mate, so ive got gaps left over that need filling in best I can

Thu Apr 20, 2006 10:45 pm

I have part one on my car as is.............

It just helps direct the air but is not needed!

Hope that helps

Fri Apr 21, 2006 7:33 pm

What is the best temp fan switch to use? 91 deg or 99 deg?
Its a twin speed fan but im planning on just using the slow speed

Fri Apr 21, 2006 11:21 pm

99 deg

Sat Apr 22, 2006 12:15 am

why not use the low speed resistor and use low and high speeds? with high speed only it'll ge a bit warm before it cuts in and the high speed sounds like you've hot a hoover in the engine bay! well noisy!

all the fuse & relay positions are there. just copy the wiring diagram for a aircon E30 for a factory style install.

Sat Apr 22, 2006 9:12 am

Yeah, ive heard about the fans being a bit noisy on full chat! Thats why I was planning on using the slower speed, id rather have the fan on a bit longer than it sounding like its going to take off!
I dont know what the ideal running temp of the engine should be though,
I was going to run with the 91 switch and see how many times the fan cut in

Sat Apr 22, 2006 1:52 pm

stevetigger wrote:99 deg

^^^^^^^^^^^^^^

Sat Apr 22, 2006 2:14 pm

DanThe wrote:Yeah, ive heard about the fans being a bit noisy on full chat! Thats why I was planning on using the slower speed, id rather have the fan on a bit longer than it sounding like its going to take off!
I dont know what the ideal running temp of the engine should be though,
I was going to run with the 91 switch and see how many times the fan cut in

Engine thermostat sets the running temp of the engine, and the electric fan should play no part when the car is moving.
All the fan stat does is set the minimum temperature of the water in the radiator when you're in traffic or stopped.
I'd go along with the connect both approach. I've just got the high speed connected, and it really is noisy when it's running.

Sat Apr 22, 2006 2:19 pm

99 is far too high! thats almost near boiling point and i would only go with 88/91.

Oil and engine optimal running temp is at 8o deg cel why would you want to run the engine to 99deg

Andrew

Sat Apr 22, 2006 5:32 pm

Andrew wrote:99 is far too high! thats almost near boiling point and i would only go with 88/91.

Oil and engine optimal running temp is at 8o deg cel why would you want to run the engine to 99deg

Andrew

Whats happened to your normal user name dude ?

It depends where in the cooling circuit the sensor is mounted, if the sensor is mounted in the thermostat housing it's getting a true reading straight out of the engine but it depends on the car/engine lay out some sensors are mounted in the cooler side of the rad so the switching point is changed to suit.

My ECU controls my fan, the sensor for the ECU is in the thermostat housing and the switching point is set at about 95 from memory. This switching temp equates to just below half way on the temp gauge, stood still in traffic on the hotest summer day it won't go above half way on the temp gauge but the fan does run quiet a bit at speeds lower than 30mph.

I want wire mine up so it has two speeds/switching points or see if i can fit a small mechanical/viscus fan

The boiling point won't be 95-100 like normal water because the cooling system is pressurised and the coolant might affect the boiling temp as well ?? I'm not to sure what the boiling point would be under pressure with coolant though ?

Sat Apr 22, 2006 6:28 pm

The sensor is either going to have to be mounted in the top hose in a piece of tube or in the thermostat housing as there is no plug in the radiator. What fan are you using Andy? You say it runs for too long, in that case the 2 speed is prob going to be the best way then.
Thanks everyone

Sat Apr 22, 2006 6:29 pm

Andy nothing up with my User name just i dont like to log on with my Admin account on other computers away from home so i made That Andrew account. (For security reasons)

RE the boiling point, yes your right about the boiling point being raised with the use of Coolant and higher pressures, but the higher the temp in the cooling system the higher the pressure! The Temp fan switch i have on my car is the same as the Thermostat (91 deg low speed and 99 high speed) And when the needle hits half way the low speed switch kicks in.

The switch is plumbed right into the Thermostat.

Andrew

Sat Apr 22, 2006 6:34 pm

Sorry for being ignorant, but what engine is yours Demlotcrew? Did you have an existing threaded hole in the stat housing?

Sat Apr 22, 2006 6:36 pm

DanThe wrote:What fan are you using Andy?

I'm using a single Pug 205 fan

Andrew has an S14

Sat Apr 22, 2006 6:39 pm

Demlotcrew wrote:Andy nothing up with my User name just i dont like to log on with my Admin account on other computers away from home so i made That Andrew account. (For security reasons)

Ah, right

RE the boiling point, yes your right about the boiling point being raised with the use of Coolant and higher pressures, but the higher the temp in the cooling system the higher the pressure! The Temp fan switch i have on my car is the same as the Thermostat (91 deg low speed and 99 high speed) And when the needle hits half way the low speed switch kicks in.

The switch is plumbed right into the Thermostat.

Sounds like your main switch point is similar to mine

Sat Apr 22, 2006 6:44 pm

Yup mate sure does,

Thing is tho on the S14 the water temp goes all over the place, The fan is very powerful and cools really well, if im at the light the fan will come on (as the engine runs hot all the time) then once i pull off the temp will drop to just over the quarter mark. Then climb back upto the just below the half way mark. The oil temp is very constant tho.

Andrew

Sun Apr 30, 2006 11:25 am

Does anyone know what the outside diameter of an E36 aircon fan is?

Sun Apr 30, 2006 12:17 pm

Does anyone know how many horsepower the M20 uses spinning that fan? I'm guessing at 5,000rpm it could be around 2-5 HP. Any dyno data?
If it is worth changing for an electric in a standard car what electric fan would you use?

Sun Apr 30, 2006 12:27 pm

Ive been told about 6hp can be gained by using an elec fan, but back to the question

DanThe wrote:Does anyone know what the outside diameter of an E36 aircon fan is?

Sun Apr 30, 2006 2:09 pm

At 5000 RPM presumably you're are moving forwards at a fair rate of knots. The airflow past the fan will be spinning it, and the power absorption from the engine is negligable, especially as the viscous coupling is likely to be uncoupled anyway.
Electric fans don't run on nothing. To produce the same airflow, an electric fan will absorb at least three times the power from the engine, than the standard viscous fan, brcause of the inefficient processes of producing electricity with an altenator and then turning it back into motion with an electric motor.
AKAIK, the E36 fan is the same size as the E34, and will fit into the top and bottom rails of an E30 rad frame exactly.