Testing dual radiator fan speeds?
 

Question. I am wanting to see if my fan will run both the high and low speeds with a manual override. (Checking to see if the fan is operating properly, as I've never heard it run accept when the A/C is on, which I know the HS side will kick on immediatly, and does just fine)

Car year is 1997 318ti/M44 (1/1997 build)

I've disconnected the radiator sensor plug, and can bridge the brown -> Black and get the high-speed setting to kick-in, but, when bridging the other side of the plug to brown.......I get nothing on the low-speed side. (Think it was the green stripe side)

I did this with ignition key on (engine off).

I've also seen a post mentioning that the high-speed relay (magenta in color) if bad could also cause this, where the HS side works but LS does not.

Long-story-short, how can I manually test the low speed fan?

This is a fairly common issue with these cars. The fan will work in high speed mode when the A/C is turned on, but low speed never kicks on. I've heard of people jumpering it and getting low speed to kick on, but that's only while testing it. Up until a few weeks ago, nobody had a remedy except for hard wiring it to a switch and manually turning it on from inside the car. Then someone figured out a way to bypass the ecu and it functioned normally. Then... member "Noneone2" figured the whole thing out! It's the high speed relay. I know, why would the high speed relay be bad if the fan operates in high speed and not low speed? Because a faulty high speed relay leaves a circuit open on the low speed side that prevents it from operating in low speed mode. Here's his explanation:

Jess is correct. The HS relay contact is interlocked with the LS relay.
Additionally, the LS relay coil is interlocked with the ECU and the low temp contact in the radiator temp switch. This is the reason why the fan did not run when you bridged the other side of plug to the brown (ground). The ecu input is open. The LS relay coil has to be energized thru the ecu and the radiator temp switch contact. Here is the schematics. Follow the blue line for energizing the LS (low speed) relay coil. The ecu role is circled in blue. On early models, the ecu has no role in the aux fan operation

Thanks for the feedback...... Yesterday I did pull the HS relay (magenta in color?) and pulled the cover off. The internals seemed as-new, although I guess something could be amiss there (the diode) and I'd not know.

Now that its hot out (and I've got the head back on the car), just realized after owing the Ti for a few months the only time we'd hear the fan is when the A/C was running. Watched the car idle until temp was mid-way and no fan and the temp creeped up a tad more so I turned it off. (considering the A/C turned on adds heat to the radiator and its just not going to expend the heat in 1minute)...........

I'm gonna run to BMW today and pick up a HS relay and a new temp switch.

I never sat down and actually studied the schematic. All credit should go to Russ(Noneone2) and Bazar01 for taking the time to figure this out. Hats off to you guys! Bazar01, the schematic really gives a good visual understanding of how the circuits function. I think the reason it's confusing to people is because if the fan only works in high speed mode, one would think the high speed relay is functioning properly and since it doesn't operate in normal speed mode, the normal speed relay must be the culprit when in fact it's exactly the opposite. Replace the HIGH speed relay and it should fix the problem and allow the fan to work in normal mode again. Of course this probably only covers MOST cases. There's still a very slim possibilty that a faulty temp switch, pressure switch, fuse or fan motor may be the culprit, but I think it's safe to say that if your fan comes on when you turn the A/C on, but doesn't kick on when the engine idles for extended periods, you should probably replace the high speed relay first.

Thanks to all.....I'll update the posting after I pick up the relay and switch today.

(I'll have to post-up a nice fix I did for the glovebox, when the lower-left plastic stub was snapped off....vs.... buying a new part)

Good stuff guys! Does anyone know the parameters for the fan to run in LOW? I'd assume a fully warmed engine, in the summer, sitting still at idle would turn it on?

Anyway, I don't ever recall seeing my fan run when the A/C was not on.

I guess depending on if/how the ECU comes into play, the radiator switch is set for 80C/176f LOW, then 88c/190F HIGH..............

(On a side-note, its purely amazing at how often the words "we will have to order" come from my local BMW dealer. I found a thermostat...Stant...at AdvanceAuto, they will also order me a 2Speed switch to be here tomorrow, and the HighSpeed relay the dealer had to get from another in the area)

Engine fully warmed up, temp gauge sitting at 12 o'clock, idling in traffic or in the driveway with the hood open, you can hear\see it.

If the fan don't run in low speed, there are 3 possibilities.
1. High speed relay normally closed contact is bad
2. Resistor mounted in the fan is open
3. The slow speed relay control circuit is not closing, from either the absence of ecu input or from a bad radiator temp switch

Anyone have the part number for the high speed relay? I just went out and checked my car, fan only comes on with A/C.

Here you go. Assuming this purple one is really it!
http://i44.photobucket.com/albums/f2...8/a89d701a.jpg

Ok well now I feel dumb, lol, I should have realized it was printed on the darn thing. Thank you Cirrus, you are always a great help.

Mine doesn't run low-speed.
It only runs on high-speed I guess mine needs a new relay.

I did replace the HS relay along with the dual-temp radiator sensor switch, and no low speed. (Does anyone know if you can still do the override for the lowspeed from the sensor plug? The HS does override fine.

Do it on the relay/fuse board in the fuse box under the hood, just like in this link here that he does on the ABS relay; http://www.318ti.org/forum/showthread.php?t=14322
http://www.318ti.org/forum/attachmen...2&d=1171226494

But make sure to identify the right LS relay and the right 30 and 87 pin sockets on the board cause they are not the same location as the ABS's above though.

Here below is my 1994 318 sedan fuse box layout. The LS relay location is #15. I’m not sure whether is it the same as your guys’ ti?
http://i569.photobucket.com/albums/s...x_Location.jpg

And here my new LS relay replacement p/n 6136 1389 105
http://doozaadoozaa.webs.com/immage/yellowRelay.jpg

However, this bridging does not tell that there is no faulty over the trigger wiring harness form the sensor to the dme and from the dme to the relay nor the relay is good since we have override them all. It just tells us the fan and the fuse are good though.

The way to test the relay is just switching the LS relay to the A/C compressor relay or #14 in the fuse box layout above, if they both are the same as those of mine, and test run the A/C. If the compressor works properly, the relay is good.

The way to check or override the LS signal is kinda tough though. You have to rewiring the trigger harness.

1st, tap on the LS trigger / green stripe or whatever color from the sensor socket cable.

Then undo the fuse box upper housing. There will be 4 hex screws that hold it as the realoem layout below:

http://www.realoem.com/bmw/diagrams/u/x/239.png

Next, locate and tab the other side of the rewiring cable on the 85 pin socket wire under the relay/fuse holder board.

Do you guys follow me? :biggrin:

A quick test for the low speed fan operation is to unplug the LS relay from the socket inside the fuse box. Get a gauge 18 stranded wire. Strip the insulation on both ends about 1/4 inch long to expose the copper strands. Insert one end on the relay socket at terminal 85. This bypasses the ecu and the radiator temperature switch. Reinstall the low speed relay on the socket. Turn the ignition switch to ON but do not start. Ground the other end of the jumper wire. The fan should run in low speed. If it does not, the low speed resistor in the fan is blown or open.

Considering I have a new sensor switch and HS relay, I am going to disconnect the Sensor switch, and also the plug from the fan.

In theory (right), if I jump either the LS or HS side of the sensor female plug, I should get power to the fan plug itself. That should take me to the route of either the issue is between the loop, or to the fan itself. (Possibly bad diode or resistor to the LS fan section).

But this should, I say should, eliminate the fan one way or the other.

Replaced my HS relay today and after getting it up to temp the low speed fan kicked on while it idled. My thanks to all the people who posted the great info in this thread.

Sweet! I just placed an order for a high speed relay today. $12.19 + $0.89 tax. I'll post my results too.

My issue appears to be the radiator temp sensor. At the plug, doing the test on Page 170-5 of the Bentley manual, I can jumper Black/Green + Brown and get Low fan speed. Jumpering Black/Grey + Brown turns the fan on High. It works with both my old high-speed relay and the new one.

That's what I get for not doing my research and the proper diagnosis first! ;)

DIY: Pre-fan delete mod: auxiliary fan circuit testing
 

Well! Here's my write up that might relate to this topic, I guess. http://r18.imgfast.net/users/1812/10...les/672707.gif

http://forums.bimmerforums.com/forum....php?t=1679680

that's pretty much the very first thing anyone should verify before going through the trouble of testing the relays and ECU inputs.

If it does not pass the sensor test, proceed to testing the relay interlocks and control circuit, then the ECU input.

Just so you know, people don't usually delete their electric fans. The FDM is more for the 328/M3 with the engine driven fan/fan clutch.

Very good info though and good to see pictures showing the procedure.

:rolleyes: my pleasure http://r18.imgfast.net/users/1812/10...les/672707.gif

+ I have learned more that the HS fan runs on the A/C in m44 radiator mount fan from this thread in which differ from my 94' m42 front mount fan that runs LS on A/C operation though. So, I need to do some wiring conversion under the fuse box board on my m44 fan conversion project. :cool:

Why the roll eyes? Maybe there is something I don't understand? I wasn't aware that people deleted the electric fan on the M42/44.

I mean I am referring to all the above postings, easy mate http://r18.imgfast.net/users/1812/10...les/672707.gif

Sorry, rereading my post it could come off sounding wrong. I didn't mean for it to sound that way. No worries.

Removing the fan on an M42/M44 equipped car is not a good idea AT ALL. These engines are much more prone to overheating than M50, M52, S50 and S52 engines. 9G3Series, your car is a 318i. The 318i has both a "pusher" fan (mounted in front of the radiator) and a "puller" fan (mounted behind the radiator). The 318ti only has a "puller" fan which operates in two modes. Low speed intermittent cools the radiator when the coolant reaches a certain temperature and high speed constant when the A/C is turned on. Furthermore, the 318ti does not have the clutch driven fan mounted on the water pump pulley like other e36's do. So it's imperative that the puller fan remain installed and function properly as it's the only way to cool the engine when the car is sitting at idle or the a/c is turned on.

I'm sorry, but your writeup is not relevant to 99% of the members on this forum and may possibly mislead someone into removing a critical part of the car's cooling system. I'll finish by saying that the FDM was intended for cars equipped with a clutch driven fan. This is the fan that is attached to the waterpump on the front of the engine. Again, 318ti's don't have this fan. The reason people remove this fan is because the plastic blades are known to break off and cause MAJOR damage. I've seen cases where the blades have dented hoods, destroyed radiators, caused belts to pop off etc. In some cases, people didn't even know their fan was missing blades, meanwhile the fan was unbalanced and causing excessive wear on the water pump bearings. If you google "e36 exploding fan" you'll see what I'm refering to. The only reason anyone would consider doing this mod on a 318ti is if they've done an engine swap and have a 6cyl engine with a clutch driven fan. FWIW, I plan on keeping my clutch driven fan on my S52:wink:

Well, you are exactly right to make it an elaborately clear explanation. However, my write-up is in the another social not in here, 318ti.org, though.

But thank you anyway :wink:

So just a FYI - 96 M44 HS Fan relay is part no: 61361388911 found in fuse box NOT under dash.

i deleted my fan clutch, there is a relay on the fan itself, its also dead so the first speed is gone... but not forgotten :D

so this is the easyest way to get 2nd speed instead of first without A/C :)

but i have 1 question, i checked on diagnostics and the fan starts to run on 99c degrees.
is that temperature in the engine or temp in the radiator switch?

http://s16.postimage.org/g5b7vnfn9/Image0854.jpg
image upload

need assistance
 

Great thread, but I'm stuck

Issue: Fan only comes on when AC is pushed


Tests done
1) Swapped low speed fan relay with AC relay
2) Swapped high speed fan relay with another from my M3
3) Jumped wires at temp switch. High speed fan works when jumped, low speed does not (what does this indicate?)
4) replaced fuses 16 and 41
5) Jumped plug 85 of low speed relay to ground, fan did not activate. (which is supposed to indicate the resistor on the fan is bad. True?)

Ran the car to temp where guage was past half way, but fans never turn on based on temperature. Need some advise on what the current issue is. is it the resistor? Because it isnt the fuses, fan (works at both speeds), nor the relays. Thanks!

The fan mounted resistor is open.
Before I bought a new fan, I ended up connecting the two wires that go to the fan resistor. This made the fan turn ON when ac is off but at a higher speed. I did not have any slow speed on the fan, but I was more confident the car will not overheat.
Then I finally bought a new fan and planned on retrofitting another resistor but never got around it.

No resistor
 

So I bought a resistor to replace the old one. As you can see here

I have no resistor to begin with. Why is that? is it located somewhere else on a 98 318ti? I looked all over and the wires go direct to the motor with no resistor.

Again. there is no resistor on my 98 TI fan like I have seen in some other pictures. Maybe the parts changed over the years. Everything seems to point to a bad resistor, but where is it?

Still driving every day with AC on......

The resister in newer model ti's is inside the fan motor somewhere which makes it problematic to fix. I just bought a new fan from Pelican Parts and installed it. At this point in time any original fans in our ti's are living on borrowed time in my opinon. Cheers, John

update
 

Just replaced fan swithch AND bought a new Fan. No difference. Fan only comes on when pushing A/C button. What else can it be?

Bringing up old topic.
Symptoms for my 95 318ti auto are pretty usual:
- high speed works;
- no low speed;
- checked and switched all fuses and relays (LS and HS);

Seems like resistor is gone. Anyone have part number handy?

http://s19.postimg.org/ofugo12oj/fan_resistor_1.jpg

Seems like this one might work, at least it was used on other BMW models for replacement:

Aluminum Shell 100W Watt 0.5 Ohm Chassis Mounted Wirewound Resistor
Specification:
Product Name Aluminum Housed Resistor
Resistance Value 0.5 Ohm
Power Rating 100W
Resistance Tolerance ± 5% (J)
Body Size 59 x 15mm/ 2.3" x 0.6" (L*D)
Mounted Hole Size 3.3mm/0.129"
Total Size 82 x 21 x 17mm/ 3.2" x 0.8" x 0.7" (L*W*T)
Casing Material Aluminum
Color Green
Weight 30g
Package Content 1 x Aluminum Housed Resistor

http://ecx.images-amazon.com/images/...L._SL1100_.jpg

Description:
Aluminum housing for heat dissipation, suitable for cooling plate installation, can be used in atrocious environment.
Small size, high power load, standard and non-inductive winding types.
High insulating capacity, good performance in vibration.
Multiple connection modes, easy to install.
Widely used in power supply, transducer, elevator, arena audio and high requirement equipment industry.

Cut the two wires off the resistor then twist them together. It will run both low and high on high speed. YOu will lose the low speed but you will not overheat while waiting on a new resistor.