E36 328i auxiliary fan problems

[Liam1288]

Hi guys!
I have an 1997 e36 328i convertible with the auxiliary fan not working.
I have done some fault finding and it came to a faulty switch but its still not working ill run through my tests i carried out...

Ok
1.so the fan is not siezed i can spin by hand
2. Relevant Fuses in tge engine bay are good
3. I checked both high and low speed relays that they click and checked if they have resistance... they don't so they are good.
4. Got power 12v to the high speed relay socket at terminal 30 jumped with 87a.
5. Jumping the switch harness with a wire produced nothing but relay clicks which to my understanding should've jumped the fan on but it did not budge.
6. Hmmm so next i thought id hook the fan up straight to a 12v supply and it WORKED! on both low and high...
7. So i tested the fan electrical wiring harness socket and i got no power reading on the multimeter until i jumped the fan switch harness again (to engage whichever relay and make a circuit) and GOT 12V!
So my conclusion was that by-passing the temperature switch to get 12v at the harness directly feeding the fan meant the awitch is at fault...

8. Replaced said sqitch and still nothing... hmmmm

Any help?


Pic below is of the new switch however does anyonw think replacing the switch below would help the problem?
Could it be something to do with the fan resistors? (Wouldn't think so if it worked supplied with a dirext 12v though)

Thanks guys

[Eric93se]

Sounds like a bad relay, but you tested them. So when you bench tested them, you energized the coil and while energized you used a multimeter to measure the resistance across the other two switch contacts? and got near zero (or 1 or 2 ohms which is fine).

[Liam1288]

Yeah tested them both by energizng them then testing resistance and they had no resistance (heard the beep from the meter)
Thanks

- - - Updated - - -

Im going to try bypass the switch and relay in a few mins
Also to add the A/C was re gassed last month and blows out cold air plus the coolant is at the correct level
Thanks

[Eric93se]

Yeah beep is not good enough. Resistance could be more than 200. Needs to be near zero.

[Liam1288]

Cheers! Just tested again and both are 0.01 ohms once energized

Trying to bypass both high speed relay and switch did nothing ��
Cheers

[Eric93se]

Pull out the fuses and visually inspect that they are good. Other than that, you have to do a continuity test from the relay socket to the connector at the fan. Also trace the ground wire from the fan connector to it's ground location (start with a resistance check from the connectors ground wire to a good ground point).

[Liam1288]

Cheers buddy!
Just to save a little time, does anyone know where the grounds are?

[Liam1288]

Grounds are all cleaned up and fuses replaced and still i got nothing at the fan connector until i jumped the radiator switch...
The funny thing is when i tested the fan out with a direct 12v power supply last weekend i got it to work on both low snd high but now it doesbt budge.
Another thing is ive been testing everything with just my ignition on stage 2 and A/C pressed though when my friend asked if ive tried it with my car running hey presto i got 12v at the fan connection without jumping the rad switch...
This now tells me my switch is good, its my fan (which worked last weekend) is now the problem.

Confused.com but i think im getting somewhere
Cheers

[Eric93se]

Is that the normal setup (location) for the fan temp switch on the convertible?

Try wrapping the sensor with a large rag, run the car and let it run for a while to see if the fan will come on.

[Liam1288]

Yeah i think so well there is no visible place on the radiator it could go...
I would do but the fan is off tge car now and ive finished tinkering with her for the day ��

[jc43089]

Something does not appear right, what is the other switch? The switch should be on the other side of the radiator on the end tank a few inches down. What radiator/ expansion tank do you have? The expansion tank is usually on the other side as well. It looks like you have a radiator setup for a 318.

[Liam1288]

Hi JC... im not sure, thats how i bought it 3 years ago so i couldn't say...
Ill have a look if i can see any numbers on the exp tank/radiator when i can.
As for the other switch... coukd that be another temperature sensor?
Looks like one but only has a 2 pin connection.
Cheers

[Ganymede]

Hey this should not be so complicated. Fan works with direct current ? Fan works when the ac is switched on? Fan is fine. Relays tested good ? Relays are fine. Fuses double checked (check with the ammeter) and good? Those are fine.

The problem is then the wiring from the relays to the double temperature switch's connector, or from the fuse box to the relays. You're going to have alot of fun tracing that out.

Tests : OP jump the terminals in the connector. There are DIYs on this on google please see those first. Switch the ignition to fully on first. You should get both low and high speed. If you only get high speed, your fan's resistor is gone. If you get no speed at all, then your wiring, fuses, relays or some combo are gone. Since you tested the fuses and relays to be good, then your problem is the wiring. Test for continuity etc, cut and splice new wires, find the problem and fix it permanently. That's it.

If your fan doesn't run at all when jumpered, check to see if your fan runs at both low and high speed with direct current on the connector. You may have more than one problem over the same situation. Check everything and get 'em all.

[LockDots]

Hey this should not be so complicated. Fan works with direct current ? Fan works when the ac is switched on? Fan is fine. Relays tested good ? Relays are fine. Fuses double checked (check with the ammeter) and good? Those are fine.

The problem is then the wiring from the relays to the double temperature switch's connector, or from the fuse box to the relays. You're going to have alot of fun tracing that out.

Tests : OP jump the terminals in the connector. There are DIYs on this on google please see those first. Switch the ignition to fully on first. You should get both low and high speed. If you only get high speed, your fan's resistor is gone. If you get no speed at all, then your wiring, fuses, relays or some combo are gone. Since you tested the fuses and relays to be good, then your problem is the wiring. Test for continuity etc, cut and splice new wires, find the problem and fix it permanently. That's it.

If your fan doesn't run at all when jumpered, check to see if your fan runs at both low and high speed with direct current on the connector. You may have more than one problem over the same situation. Check everything and get 'em all.

This. It's a very simple setup.

[Liam1288]

Thanks Ganymede!
I have done pretty much all those tests though the difference in variables was having the ignition from just 'on' to actually having the engine running where i got better results finding the switch to work and power was getting to the connector at the fan.
My next problem was that one weekend the fan worked as it should with a direct 12v power supply to not working at all the other weekend.
Either way, with my last results im putting this one to the fan at this stage...
Cheers!