air con fan resistor, can I replace it with any electronic r

[markus_74]

hello,

my electric air con fan in the front of radiator is now on high speed always because the resistor is broken.

can I replace it with any electronic ceramic resistor?

if yes, which resistor type and what ohm and what watt?

thank you
markus

[Brianmoooore]

Yes, as long as they are rated at a high enough wattage, and you mount them so that all the heat they dissipate can be safely disposed of. There's also the matter of the automatic resetting overload cut out included in the pack.
The resistor values are 0.8 ohm for speed 3, then 1.0 ohm (total 1.8 ohm) for speed 2, and 1.6 ohm (total 3.4 ohm) for speed 1.
The wattage rating of each resistor is the product of the voltage developed across it and the current flowing through it, but I don't have the data to calculate this. It will be in the 5W - 10W range though.

[markus_74]

hello, Brian

thank you for the info.
but the fan that I mean it not blower air con fan in the dashboard.

the fan is located in the front of the car? electric fan for cooling the condenser/radiator.

they only have 2 speed for 91 degree and 99 degree.

my 91 degree is damaged so it now only speed for 99 degree, can I put alternative resistor for 91 degree?

what type of resistor and what Ohm and watt?

thank you

[Billwill]

Have you first of all checked that the temp sensor, plugged into the top-right of the radiator is working?
Switch ignition Off.

Put an Ohm-meter on the centre wire (Green/Black) which is the common.
Put the other meter lead on the Black wire and heat up the sensor carefully with a hair-dryer or a heat gun. At 91 degrees C the Ohm-meter should show that the contact is closed.

If you move your lead from the Black wire to the Black/Brown wire and continue heating the sensor up...the meter should show the contact closing at 99 deg C.

Then disconnect your meter and with ignition ON, jumper out the 91 deg contact ie. jumper Green/Black wire to the Black wire....the fan should switch on at low speed.

Jumper the Green/Black wire to the Black/Brown wire and the fan should run at high speed.

K1 is the normal speed relay...try swopping it with K6 which is the high speed relay or swop it out with a different relay altogether.

Check fuse 3 for low speed fan and fuse 18 for high speed fan.

You can measure the resistor with your Ohm-meter to see if it is blown out...should read 6 Ohms. A new one should be at least 20 Watts I would estimate.

The low speed fan should also switch ON when you push your blue air-con switch in...no matter what the engine temperature. This blue switch energizes the low speed relay through a diode.

So to summarize....first check if the actual temperature switch is working.
Then check if the low speed relay is OK.

Then measure the resistance of the resistor.

[markus_74]

Have you first of all checked that the temp sensor, plugged into the top-right of the radiator is working?
Switch ignition Off.

Put an Ohm-meter on the centre wire (Green/Black) which is the common.
Put the other meter lead on the Black wire and heat up the sensor carefully with a hair-dryer or a heat gun. At 91 degrees C the Ohm-meter should show that the contact is closed.

If you move your lead from the Black wire to the Black/Brown wire and continue heating the sensor up...the meter should show the contact closing at 99 deg C.

Then disconnect your meter and with ignition ON, jumper out the 91 deg contact ie. jumper Green/Black wire to the Black wire....the fan should switch on at low speed.

Jumper the Green/Black wire to the Black/Brown wire and the fan should run at high speed.

K1 is the normal speed relay...try swopping it with K6 which is the high speed relay or swop it out with a different relay altogether.

Check fuse 3 for low speed fan and fuse 18 for high speed fan.

You can measure the resistor with your Ohm-meter to see if it is blown out...should read 6 Ohms. A new one should be at least 20 Watts I would estimate.

The low speed fan should also switch ON when you push your blue air-con switch in...no matter what the engine temperature. This blue switch energizes the low speed relay through a diode.

So to summarize....first check if the actual temperature switch is working.
Then check if the low speed relay is OK.

Then measure the resistance of the resistor.

hello, billwill

thank you for very detail explanation, it is very help me.

but can I swap the original fan resistor that is very expensive from bmw to just buy any resistor (ceramic) that I buy from electronic shop? I found that I can buy 20 watt ceramic resistor with 6-10 ohm.

[Billwill]

Yes you can replace with any new resistor but I seriously doubt it will fix your problem...I do not think the resistor is your problem but you will not cause any harm by replacing it; unless you have already tested it and found it to be faulty

Always advisable to clamp the resistor to a metal bracket with a bit of silicon grease in between so the metal bracket works as a heat sink to dissipate heat better but 20 Watt will in any case be more than capable of dissipating heat by itself.