Newbie.... please help !! - mind boggling Interior motor fault.

[ihookie]

Hi all... I have recently purchased a w209 clk55 which needs a bit of love. The interior fan doesn't work at all, I have power to 3/4 wires up to the motor / resistor pack and i have earth on 4th wire. Fuses are ok.

I have replaced both the motor and resistor pack - still no joy. The control unit can increase the fan speed / temperature, I have the standard clicking within dashboard which is related to the foot well door flaps. Code scanned and no other faults flagged up within the HVAC system.

Has anyone come across this issue before ? I have read in other forum posts of similar to the above but without any resolution. I am running out of options as to where to go with this, I don't particularly want to leave it with the dealership

Does the control panel play up on the clk's ? The only other thing I can say is that the main battery is weak, although i cant see any reason why the fan wouldn't work.

Any help or pointers would be greatly appreciated !

Many thanks !

 

[Botus]

do you have a consumer toys message when you start the car

on the w211 the fan stays off if the battery is low on grunt - utter mad design - fully charge a good battery and or drive for 20 mins then it will wake up - its also stops the screen washers running - how it can be legal that a car with the engine running disables two significant safety features letting you look where you are going is something to be concerned about

 

[Uncle Benz]

Maybe take a look at the sun sensor. On w203 it’s on the bonnet, middle of the washer jet grille. Probably the same on 209. I’ve seen them give erratic fan behavior before

 

[mioba]

There is a diags menu on the AC control panel for the AC itself, I dont recall the key sequence to show this, but if you google you will find it.

I remeber this from my W220 many moons ago as the the control panel was playing up and it was replaced under warranty.

Good luck and keep us posted.

 

[ihookie]

do you have a consumer toys message when you start the car

on the w211 the fan stays off if the battery is low on grunt - utter mad design - fully charge a good battery and or drive for 20 mins then it will wake up - its also stops the screen washers running - how it can be legal that a car with the engine running disables two significant safety features letting you look where you are going is something to be concerned about

Thanks for the reply.... what is the consumer toys message ? I don't seem to have any unusual messages except every now and then i have a key less entry error.
I have driven the car for more than an hour but still no joy on the fan jumping into action.
I will likely replace the battery anyhow.

 

[ihookie]

Maybe take a look at the sun sensor. On w203 it’s on the bonnet, middle of the washer jet grille. Probably the same on 209. I’ve seen them give erratic fan behavior before

I will give this a try.... is there any way to test the sensor with the exception of it raining ? I haven't seen any errors when doing a code scan.

 

[ihookie]

There is a diags menu on the AC control panel for the AC itself, I dont recall the key sequence to show this, but if you google you will find it.

I remeber this from my W220 many moons ago as the the control panel was playing up and it was replaced under warranty.

Good luck and keep us posted.

I have tried the holding of recirc & defrost to activate the hvac diagnostic. The led's flash continuously and nothing seems to happen. I assume this is because there is a permanent fault with blend doors stuck ?

UPDATE..... I had a good strong 12v signal to the main wire to the resistor.... I then re-checked the wiring and found that the same wire had an extremely weak signal whether the engine was running or not. Possibly have a wiring issue somewhere. Is this anything anyone else has come across ?

 

[Botus]

Thanks for the reply.... what is the consumer toys message ? I don't seem to have any unusual messages except every now and then i have a key less entry error.
I have driven the car for more than an hour but still no joy on the fan jumping into action.
I will likely replace the battery anyhow.

when the battery is low on charge as you turn on the key - in the speedo cluster message area - consumer whatever they call it turned off - it should mean interior toys off for a while to let the battery charge up a bit - but I see both the fan and the screen washers get taken out as well (on a feb 2006 w211)

if they meant heated rear screen, radio, nav, maps lights and heated seats - they'd have a valid point

 

[mattkh]

I have replaced both the motor
Many thanks !

Did you desk check the new fan before you installed it..??

 

[ihookie]

when the battery is low on charge as you turn on the key - in the speedo cluster message area - consumer whatever they call it turned off - it should mean interior toys off for a while to let the battery charge up a bit - but I see both the fan and the screen washers get taken out as well (on a feb 2006 w211)

if they meant heated rear screen, radio, nav, maps lights and heated seats - they'd have a valid point

Havent seen any message to be honest, but makes sense in a way. perhaps this wasn't installed on the older models.

 

[ihookie]

Did you desk check the new fan before you installed it..??

Yes, fan works fine when bench testing. I'm thinking perhaps a power supply issue or signal issue from the control unit ? really scratching head with this.

 

[Botus]

looks like much the same dash as the 211 to me - are other things working? you might just be stressing over nothing - been there done that - all it needed was 2 miles more not me returning to base and checking wiring and fuses out !!!

 

[peterws1957]

Yes, fan works fine when bench testing. I'm thinking perhaps a power supply issue or signal issue from the control unit ? really scratching head with this.

Were the fan and resistor assemblies original MB or eBay specials? Owners have reported problems with eBay units, particularly the cheap resistors not working as they should.

 

[ihookie]

looks like much the same dash as the 211 to me - are other things working? you might just be stressing over nothing - been there done that - all it needed was 2 miles more not me returning to base and checking wiring and fuses out !!!

True, I will whip the battery out and leave it on a condition charger all day and see what happens. Everything else seems to work, the control unit seems to function in the sense that i can change fan speed, temperature etc... however i can't check if the a/c works - cant hear anything clicking in etc.

 

[ihookie]

Were the fan and resistor assemblies original MB or eBay specials? Owners have reported problems with eBay units, particularly the cheap resistors not working as they should.

both original Mercedes parts. I could return or order another one but its a risk of throwing money down the drain if it not a faulty part.

 

[Botus]

air con on modern cars doesn't click clunk on and off, they moved (this might be a bit early) to an always on variable compressor from 2000 but on most cars by 2005

 

[ihookie]

air con on modern cars doesn't click clunk on and off, they moved (this might be a bit early) to an always on variable compressor from 2000 but on most cars by 2005

I will start again with the battery and work through the wiring etc. Will be something simple no doubt ! just gotta find it

 

[alexanderfoti]

W209 does not do consumer shut off etc like the w211s do (no sbc!)

 

[mioba]

.....Will be something simple no doubt ! just gotta find it

He said.....

 

[LostKiwi]

Interestingly the 230 still allows the heater fan to run though at reduced speed when consumers offline message is up.

OP - instead of measuring voltage use a test lamp to simulate a current draw. A high resistance open circuit feed will show 12v but that will drop to near zero when a load is applied.