No rad fan - fault analysis - SOLVED

[charlie8]

Not that I use it, maybe that is the issue, but just before laying up for the winter I was using to demist and noticed it had stopped working, and now of course still is

On a route to fault finding, these are symptoms

Air con light comes on when pressed
Blower ramps to fast and blows hot when set accordingly
Rear window heater OK ( so not transport mode )
Fuses all good
ECU scan - no errs or pending
Comp clutch is not engaging when pressed ( no noise or rev drop )

A few more checks I can do from searching, but some questions first you might be able to help with and best next step

• The coolant would have to be near on empty to not work at all ? ie needs a very low pressure. Can I check that by pressing the release valve just to see if any hiss, is there a visual anywhere on correct pressure

• Should I see a fan come on instantly when switched on ?

• The corroded green wire to the fan some have mentioned - is that the best next step to check ?

• Where is the compressor, which end host the magnetic clutch - is spraying it with WD safe, clutches don't like lube ?

• Can I prove the comp is OK by loading the connectors directly ? is that safe

Again, I can well live without A/C but its just something that is broken and that bugs

[Ducklakeview]

If the compressor clutch isn't engagng, it's more than likely low on pressure, ie refrigerant. If you are planning on getting it done, I'd do it now - R134a gas has gone from £2.50/kg in Dec when I last bought some, to over £30/kg as of yesterday!

Mike

[charlie8]

Wanting to check I can siit is queue without worry in the sun, let the car idle when I got back home, and the temp crept to 1 segment below red without the fan cutting in, so that tells me I have a fan problem in general

Not sure where to start with that one, thermostat is good as I get hot air, but just no fan

[Ducklakeview]

Thermostat could well be stuck closed. You'd still get hot air, but no water flow through radiator.

Mike

[charlie8]

Hmm I can do 50+ miles with many minutes of stationary and temp solid in the middle. Also had to leave the car for 10 mins on fast idle after a 30 miler before it moved off center, so that suggests the full flow must be working. I was quite impressed with how cool the straight 6 must run before the needle moved and no fan responded.

I am predicting the A/C is dead as it does not get a fan on response, before the comp engages - so I think I'll go do a check on teh connectors

Best i found this now and not in some long jam in the sun, nothing raises the pulse like a rising needle when your stuck in it with no escape route

[Monkeydonkeyratmagic]

Is the AC belt actually there? Could have snapped.

[MACK]

Im a little confused from the description what the actual symptoms are here but are you sure it's A.C. specific rather than the in car heater fan in general. If your saying the fan is only blowing (whether the AC is pressed or not) on full flow but not on other speeds. have you thought about the resistor for the fan that's located behind the glovebox. It's a common fault on e46s but not so much on e85s.
If you thinking thermostat, again on Bmws with the m series engines (Not to be confused with m cars themselves) a thermostat sticking open (so over cooling rather than overheating) isn't uncommon, I had this myself on an e46. Does the needle sit vertical on a decent motorway drive without stopping etc?

[charlie8]

Sorry, all blowers/fans are good and hot

Given no fan on heat AND no fan on A/C - no fault lights etc I think this is fan as there would be no way the ECU could tell its not spinning, but how do I test ie activate to prove it directlty ?

There are 3 terminals, gnd, + and then the PCM pin. Direct voltage to the pin on the fan do nothing, so guess it needs the PCM signal OR its is fried. It spins by hand so not seized, the green terminal for PCM was hard, but seems stuck into the terminal enough

How can I direct current feed to turn the fan to test it before I spend wasted money. I've searched around but nothing shows up on how to do this - only 2 terminal fans, which are old now

THanks

[charlie8]

Popped out the module/motor, noticed some green dust corrosion on the windings and when I poked it, the wire separated/split apart, so thats pretty conclusive on why it might not have worked. Looks a bit tired all round

Now I just need to hunt a spare down ... I've put the feelers out in wanted

[charlie8]

So mystery continues. A kind member on this forum supplied a fan, quick plug and play and that does not work too. So seems something else at play

I then disconnected the coolant sensor, that does not activate the fan also, and indeed no engine management light comes on

So this is is really puzzling, unless the engine has to exit the closed looped phase of warm up before throwing a code ? I literally started car with no sensor, checked fan, check dash and stopped.

Any clues ?

I have the diag s/w on order to try and look deeper, but the fundamentals puzzle me - not the first time

[charlie8]

Bought cable and got the INPA s/w installed and fired the signal to the fan, nothing, error code saying fan1 circuit, tried my purchased spare & the same. Then found a video saying you should see about 5V pulse at the pin from the car when activated, I had nothing. Then the small green wire to the the car connector looked quite frail so decided to carve into the wire to see if any signal there to rule out connector itself and the cable just scrapped through, no wire, I cut a small section off and bit it hoping to find wire with my teeth and it was literally just dust. So pulled back loom, and finally found good copper in the wire a couple of inches back, I jumped a new piece into the rad fan wire direct. Back to INPA and bingo a working fan ( my original ). So its solved, it was the wire

So a break in the motor windings means nothing and guess there are many backups, that threw me.

Stepping up the INPA fan test to 90% nearly blew by garage away, quite a force. Frustrating how difficult it is to debug these sorts of issues with no simple electronics on the car, however once i had the s/w it was quite amazing how you can control the cars 'guts' with a button click and was easy to pin stuff down.

All that clever BMW engineering and after 10 years the wiring literally rots

Solved by help from this forum as rotting rad fan wires was logged in the search and my spare fan was sold to me a member here

Anyway, hope this helps. Its funny how I reckon this was broken yrs ago, yet I was driving a car that potentially one day in a hot traffic jam, the temp rising will have caused me horrendous issues. It was only me testing it on a long fast idle, when the sun came out in a big way last week, I realised the fan was not kicking in.

Anyway hope this helps for the record

[Ducklakeview]

Told you, repaired many of those little green wires

Mike

[MrPT]

Well done.

On my last Z4 the fan connections were broken in the wiring loom where they are bundled together with a screen wash tube. Had to trace every connection end-to-end to the DME before I found it, so you’re lucky yours was near the fan pack!

I was also amazed at how efficient the radiator is. I probably ran the car for over a year before noticing the fan wasn’t kicking in and never had a problem with temps until a heatwave + traffic jam.

[SonnyA85]

Bought cable and got the INPA s/w installed and fired the signal to the fan, nothing, error code saying fan1 circuit, tried my purchased spare & the same. Then found a video saying you should see about 5V pulse at the pin from the car when activated, I had nothing. Then the small green wire to the the car connector looked quite frail so decided to carve into the wire to see if any signal there to rule out connector itself and the cable just scrapped through, no wire, I cut a small section off and bit it hoping to find wire with my teeth and it was literally just dust. So pulled back loom, and finally found good copper in the wire a couple of inches back, I jumped a new piece into the rad fan wire direct. Back to INPA and bingo a working fan ( my original ). So its solved, it was the wire

So a break in the motor windings means nothing and guess there are many backups, that threw me.

Stepping up the INPA fan test to 90% nearly blew by garage away, quite a force. Frustrating how difficult it is to debug these sorts of issues with no simple electronics on the car, however once i had the s/w it was quite amazing how you can control the cars 'guts' with a button click and was easy to pin stuff down.

All that clever BMW engineering and after 10 years the wiring literally rots

Solved by help from this forum as rotting rad fan wires was logged in the search and my spare fan was sold to me a member here

Anyway, hope this helps. Its funny how I reckon this was broken yrs ago, yet I was driving a car that potentially one day in a hot traffic jam, the temp rising will have caused me horrendous issues. It was only me testing it on a long fast idle, when the sun came out in a big way last week, I realised the fan was not kicking in.

Anyway hope this helps for the record

My fan isn't working.

What did you use to replace the wire?

Would speaker wire work?

[charlie8]

Yes, its just a pulse, so load is very small. I used 12V lighting wire I recall

6 months on, through the extraordinary hot summer and needles' not budged from middle, i hear the fan now and again ...