indimb

Hi All,

As we all know there is only one variable speed radiator fan in the w203 and it works on input from (1)The refrigerant pressure/temp sensor and (2)The coolant temp sensor.

If Im not mistaken, the following are inputs taken from the pressure sensor:
Refrigerant Pressure: <12 BAR - Fan Off
Refrigerant Pressure: >20 BAR - Fan On Full
Refrigerant Pressure: >12<20 - Variable speeds(Incremental steps of 20%) depending on refrigerant pressure.

I don't have/know the inputs regarding the refrigerant temperature and the variable speeds of the fan accordingly.

Now my question is, what inputs are taken by the fan from the coolant sensor? Is it just ON & OFF when the temperature reaches a certain point or is it in steps just like the pressure sensor? Thanks

C230 Sport Coup

Agreed. Too complicated for my simian brain.
Hopefully Glyn with his giant brain can answer this one.

indimb

Ok, shall wait for Glyn to respond then

Glyn M Ruck

OK. From your PM's you have recharged the system. This is step one in diagnosing the HVAC on any Benz. No refrigerant pressure, no HVAC operation to protect the compressor.

Then there are a long list of things that that can cause your problem which is why you really need a Star to diagnose this or you are going to end up throwing parts at the thing to try & cure.

Firstly ~ is your HVAC guy happy that the main components of the HVAC are in order. Compressor, Condenser, Evapourator, Expansion valve, Dryer etc.?

The Variable speed radiator/condensor fan has a controller on a fly lead from it. The fan is sold as one unit with the controller. The fan takes it's speed data from the ECU. This can even be remapped with a Star. The ECU takes it's inputs from the engine temp sensor, the HVAC pressure/temp sensor in the condenser, the HVAC in dash Controller. The HVAC in dash controller takes it's inputs from the vehicle operator and the cabin temp sensor/s with it's sniffer fan in the overhead console & the ambient air sensor. Cars with Thermotronic rather than Thermatic have further refinements such as a sun sensor on the hood/bonnet etc. The whole system communicates over a CANBus.

I have showed you where to find the HVAC documents in the Wiki.

Possible problems.

The engine fan should switch on the minute you engage the Aircon.
The fan controller might be toast.
The dash controller might be toast
The dash controller might not be controlling the blend flaps properly. A blend flap might be stuck or have a faulty stepper motor.
One of the sensor feeds might be corrupt or a sensor is faulty
The overhead temperature sensor might be faulty. Some cars have a second sensor in the dash which might be faulty. There is also a dew sensor.
You could have an EIS fault
You could have a CANBus fault
One of the main system components may be faulty.

You either need to find the best HVAC shop in town or get the car onto a Star DAS.
The only way is to go through the system methodically.

Good luck.

indimb

The mechanic scanned the car with a scan tool called "Launch X431" however this was before recharging the refrigerant and it only threw up an error code for "Low Refrigerant". Since there was practically no refrigerant, could this have prevented other error codes to appear? Do I need to get the scanning done again(after the recharging) for more relevant error codes to be thrown up and does it need to be done only on the Star DAS tool?(As mentioned above, my mechanic has the Launch X431 tool only).

HVAC guy's Diagnosis: Replace compressor valve.
His Reasoning: The compressor isn't generating enough pressure when it comes on therefore the control valve needs to be replaced.
My Reservations: The max pressure seen on high side is 225psi and on the low side is 40-50psi. While I agree there is a gap in the low side pressure but is 225psi on the high side really low? Moreover, he is not offering any guarantees on the problem being solved with the valve replacement and who knows, maybe the compressor itself has gone bad?!? So I have a feeling he is just throwing parts.
My Dilemma: Go ahead and give it a try with the valve replacement at the cost of approx $200 USD or invest a similar amount in a low cost scanner and start from there.

Negative. The fan does not start when aircon is switched on but neither does the compressor. The compressor kicks in after 10-15 minutes and so does the fan. The low pressure pipe starts becoming cold and cool air starts blowing in the cabin and then all of a sudden nothing. Just plain air, sometimes even hot air but the radiator fan stays on. The cool air comes back on after a few minutes(upon raising the RPM), only to go away again in a few seconds. This cycle keeps repeating again and again. Its as if the compressor has a mind of its own and keeps going ON & OFF rapidly.
Thanks a million. Greatly appreciate all your help thus far, Cheers.

Glyn M Ruck

The trouble with a Launch is I don't know whether it can read all Benz codes & it certainly can't run Star emulations. Don't waste your money on a cheap scanner unless you are going to keep it in the glove box for reading the odd standard code.

You might have answered your own question though. If the fan & compressor don't start when you turn the aircon on then either the condenser pressure temp switch is faulty, the controller is faulty, but most likely you are not reaching adequate system pressure until things have been running for a while. I don't know if a new expansion valve will fix this.

This is the problem. No Star & you are going to have to try things which could get expensive.

indimb

Will this model work for my vehicle? Im planning to order the External HDD version and install & run it of my macbook.

MB Star Compact C4 Fit All Computer Update to 2013.07
http://www.uobd2.net/wholesale/mb-st...-computer.html

OR
Mb Star C3 for Benz Trucks & Cars 2013.09 version
http://www.obd2tool.com/goods-145-Mb...7+version.html

Thanks for your valuable advice.

Glyn M Ruck

Either will work. Just make quite sure that you have the right host computer with the vendor. I've only ever operated Star from IBM T series laptops.

wwhyukaa

Both work, MB Star Compact C4 is better.

indimb

Thanks alot Glyn. Unfortunately, I don't have an IBM T so need it to work of a macbook or windows xp laptop at the very least.

From what I've read, C4 is a pain to setup and requires you to register over the internet and download the required files. Considering both of the above tools will most likely be Chinese versions, would you still recommend the C4?

I don't mind the old version of Star DAS(C3) as long as it works with my car(2001 C200 CDI), stable, easy to setup/operate and runs on the macbook(or windows xp).

In fact, I would be grateful if you can suggest an even older version of Star DAS(older than the C3) as cost is the most important factor here and mine is a really old car(Nov 2001). The tool will be used only for this car and the sole diagnostic capability/feature I need is to diagnose the "Air Conditioning", Thanks alot.

Glyn M Ruck

You can run it on any Windows XP PC that has the correct plugging. IBM retained serial ports & the like long after others. Understand that there is no USB compatibility here.

samaritrey

You can find express card adapters now that seem to work with star. I use a VMWARE image on my t420s which is a windows 7 64 bit computer and the image works great on it as well as the express card adapter I found. You can't just buy any express card adapter though as many don't work I stumbled upon one on amazon that worked for many people connecting to old switches and network devices which is why I tried it and have been really happy with it. Running the vmware image on a modern i7 vs my old 2.26 ghz Pentium M is just unbelievable. It does also help to have the image on an SSD if possible.

VVF

Trey, would you mind sharing the name of that adapter? I am thinking of acquiring a STAR clone as well...

samaritrey

The model I got is Syba SD-EXP15005 can be found on many different sites just Google it. Mine came from the river in South America

indimb

Many thanks Glyn & Samaritrey!
After days of research and your valuable guidance, I have come to understand that there is a sea of options out there... thankfully.

I have narrowed down on the following options keeping cost in mind:
(1) Procure only the C3/C4 multiplexer with cables and download & install the software(cracked) yourself on external HD and run it of any laptop.
(2) Procure the C3/C4 multiplexer with cables & pre-installed software on external HDD and run it of any laptop.

Which of the above(or any other) options would you suggest? Thanks

Samaritrey, Would I still need an external HDD or just the image of the software on SSD will suffice in the expresscard setup? Also, unfortunately I don't have PCMCIA slot in my macbook pro(preferred laptop), any idea if this usb to serial adapter from SYBA will work --> http://www.newegg.com/Product/Produc...82E16812186105
Could you possibly direct me to a post or article on how to setup such a vmware/image based DAS system including details of all the required software, Thanks in advance.

krazzdav

Hi all....I can verify that you can use a USB to DB9 adapter. I am not sure if the chipset on the Newegg.com will work though. After doing much research before buying mine I would recommend using one that has an FTDI chipset. The one I purchased is from GearMo and worked flawlessly. I got the 6inch adapter but they also sell a longer one if you prefer.

As for the C3/C4 dilemma I too heard problems and incompatibility with the C4 so I bought the C3 mux. I have a 7/2012 developer mode version of the software loaded into a WinXP virtual machine on a Win7 computer and works great. It also states when running DAS that as of 2012 it will need started from XENTRY. Luckily mine I don't have to because doesn't XENTRY connect back to MB to verify authenticity?

I would recommend before you purchase any software make sure it has the developer mode. The link you posted doesn't say anything about being in developer mode.

indimb

Many Thanks krazzdav. The C3 that I'm looking at does not state "developer mode" anywhere so most likely its not the required version. Can you pls share the link from where you ordered your C3 and also did you get it along with the software or just the mux? Thanks again.

VVF

indimb, from what I know, one can unlock the developer mode using a serial number. I.e. it's not a different version of DAS. Where to get the serial is a different question though.

Hehe Thanks, I will give it a try then.

krazzdav

indimb you do not need the developer mode and will have all of the things a typical person will need in that version of DAS like VVF stated. As for unlocking it into Developer mode or is another version I have no clue For me if I was going to get the software I would want all of the bells and whistles I could.

I myself only purchased the MUX with all of the cables as I had the software from somewhere else already.
I can't recommend one seller over the other but bought the mux from http://www.aliexpress.com/ Do a search for something like C3 Star and u will see several different sellers. There were a couple that had funny user names and no ratings so be careful and check the reviews out.

indimb

Hi All, Happy New Year!

Thanks to all your valuable advice, I have narrowed down to the following 2 options. One is from aliexpress and the other from dhgate.

This one seems to be just perfect and comes with a 320GB external HDD. The only concern is that I haven't heard much about this dhgate site and seller has done only 50 transactions thus far but has 100% rating though - http://www.dhgate.com/product/2013-m...3-1|2142133751

This one seems to be from a better seller but the size of external HDD is only 80GB. So I'm guessing some software would be missing? - http://www.aliexpress.com/item/Profe...544203898.html

Both are almost the same price, please help me select one, Thanks alot!!!

Skye168

SlashW203

Have run into similar problem recently (cooling fan will randomly turn on, even when not needed). Independent shop (works only on MB, BMW & Mini) ran full HVAC diagnostics & everything looks good on the HVAC end. Replaced the AC pressure switch on the condenser (B12/2 on the diagram that I've seen online). Did not fix the issue. Next step is to replace cooling/radiator fan which is being ordered. Mechanic is confident this will fix the issue. Fingers crossed.

tjts1

If he really did run a full diagnostic of the HVAC he would have figured out where the problem is before replacing the temperature/pressure sensor in the condenser. Be wary of this shop.

SlashW203

No, the shop is one of the best in the area for BMW/Mercedes.. I was the one that insisted on replacing the sensor first before doing the cooling fan, which will be this week. It's usually the B12/2 sensor that fails in the problem I was experiencing & I didn't know there was also a control module in the fan. The problem still exists but only 50% of the time, so the sensor probably needed to be replaced anyway..

tjts1

Ok, it's your money.