victordakhteh

Hi Everyone,

I'm looking out here for any former or current G55 owner's years 2003 and up about this unsolved issue I have before I send mine into the dealership to drain my wallet.

I'm sure you all have noticed the loud noise our engines make when the a/c is on or when it is in need of cooling down when you're parked and what not. Anyways, so my mine has stopped completely, the fan between the grill and radiator, aka auxiliary/radiator fan, i don't what you all call it, but I refer to it as the "aux. fan" for short.

Now for some reason it has stopped working therefor causing my a/c to not really work well and quickly turns into warm air and I have noticed that the idle (or when I am at a stop) position the temperature is closer to 100c whereas before it was closer to 80c which is where it should be at, at least when I drive.

I have not overheated knock on wood** however it is concerning to me.

I have so far taken it to my uncles shop, but he's not an expert on mercedes benz, however we discovered a code error on the diagnostic test which may be related to the issue, P2316*

Now I ran power to the fan and it ran perfectly, so I know its not the fan itself. Then I tested the relays, and no problems there. Now I am left with the possibility of two different sensors or the climate control unit. If it's the climate control unit I know I can switch that in a heart beat. But the sensors are not something I can do myself. Oh and I also recharged the a/c incase it wasn't detecting the pressure but that didn't help either.

Now is there anyone who's had this exact issue? I would love some insight from anyone who may have a solution, or had this issue.

Thanks for reading

RA032924

Hi,
I had a similar issue when i had some front end work done on my car(03 G55 AMG), and it turned out one of the AC switches were wired incorrectly. Could be as simple as poor connection, or a bad switch.
I would suggest checking the connection to the switches first, and them consider replacing them if that does not work.
Hope that helps.

victordakhteh

At this point I have no idea, I have done a lot more research since you have replied and I am starting to rule out the temperature sensor because the temperature readings are not off and are accurate. I am thinking of just going ahead with the climate control unit and getting it to give it a try, it's the last thing which makes sense. I am just surprised that it may in fact be a bad unit now, I guess when you use it more the more likely it is to mess something up. Thank you for your tip. I appreciate it

BonitaBeast

When you said you put power directly to the fans and they worked, where exactly did you hook up the power to the fans?

There is a fuse box located on the very left side of the dash to the left of the steering column. It is accessed by opening the drivers side (left) door and you will see a little panel that can be removed. I believe the fuses for the aux fans are letters H and G in the picture below. My fuses came loose over the years and caused electric arcs and melted my fuse box. My fuses also blew. One day my aux fans just didn't work. I didn't overheat. My coolant temps didn't go crazy, but I just noticed the fans stopped coming on. Lucky I noticed it the same day it happened.

I replaced the fuse box and the fuses and all is now perfect.

victordakhteh

Hi there,
Thanks for your response, as you said my temperature reader hasn't gone crazy, it says that I'm in between 80c to 100c and on hot days it gets closer to 100c whereas you know the normal temp. reading is 80c. Haven't overheated, just noticing that the air doesn't cool down when I run a/c so I just stopped using it. I have checked all the fuses and they were fine, however I did noticed that fuse G looks slightly deformed from melting. I ran power directly to the wires running to fan on the side the engine compartment and it worked. I spoke to a mechanic and he said on the 03' the fan module is apart of that fan which may be the issue, however if that were the case, I don't see how my fan would have worked when I ran power to it. I could try replacing those fuses as an extra set step since the issue you describe is exactly the same problem I have. However I recall when testing the fan relays I sent power in and the fan started moving but it wasn't strong, my uncle said it means that there was a break in the circuit but what means I have no clue. It's starting to sound like the relay to me in my opinion but then again, I have no idea. I'm not opposed to going to the dealership, however if it's something I can switch myself like a fuse or a relay, I'd rather save some money. Oh and to rule out the climate control unit, I already tried a new one and it didn't help so I sent back the new climate control unit and am back to the old one which works fine. Let me know your thoughts, sorry for the whole story I wrote but I appreciate any thoughts you have on this matter. Thank you

BonitaBeast

Looks to me that you found the problem right there. The deformed fuse housing is exactly what the issue was for me. The melted plastic piece means your fuse(s) have also come a little loose causing not constant contact between the terminal and fuse which causes arcs and heat; causing melting and deformity. I had to special order the fuse box itself. It wasn't that expensive but took a little while because no one had it in stock. I think www.parts.com had the quickest delivery time. I know I have pictures of the melted fuse box somewhere. I just cant find them at the moment.

I'll post them when I do

victordakhteh

Sounds like its worth a shot. Was it difficult to do it on your own or rather easy? I did notice that some fuses looked slightly loose. And did you replace the fuses too or just the box and the two fuses for the fan?

and how much did you pay if you don't mind me asking, I just want to know if its a huge difference from how much you got it for.

victordakhteh

Another question, do you still think it could be the fuse box even if theres still a charge in the fuses when I power tested them? I'm just wondering if logically thats still possible to detect power in the fuses even if the fuse if deformed. I pulled out one the fan fuses and that were deformed and stuck a new one in, but didn't work :/

BonitaBeast

Yes definitely can be the box even if there is still some current going through the circuit. The actual connection might not be good but there could still be one. There could be corrosion in there which is a possibility. Mine had some and the connections were all loose. I didn't want to risk any more sparks in there with high current traveling through the box. I wouldn't take the chance of using the damaged one if I were you. The box itself cost about $80-90 if I recall correctly. New fuses were included.

This is what mine looked like melted. I tightened some connections in there and the fan worked again but I didn't want to take the chance of using a box with damaged stuff so I waited for the new box to come before I used it. Not a difficult job at all. Just make sure you disconnect the battery when working on this part.

BonitaBeast

Here's the replacement one:

victordakhteh

Hey there again,

So I just ordered the fuse box from the dealership, I bought the new relays just incase and switched them out, but the relays didn't help, So now I'm just going to wait for the fuse box and hope thats it.

Now whats the reason for discounting the battery? I'm not to technical on these things and I didn't do that with the relays I just switched, did screw up the relays by not discounting it? I will make sure I discount it for the fuse box though.

BonitaBeast

It's not the relays you could mess up but the electronics of the car you can mess up if you don't disconnect the battery and you are connecting and disconnecting major parts of the electrical circuits of the car. Many circuits run in and out of the fuse boxes and relays. Some are live all the time and some are switched (meaning they only turn on when the ignition is on). Disconnecting the battery when working on the electrical is always a precautionary thing. It can prevent any fault codes from showing up in case you disconnect any of the live circuits when unplugging any of the fuses.

Hope that clears it up a bit.

victordakhteh

Okay I understand now, makes more sense, so from what you are saying it seems like that I "may" have messed up the circuit right now, but then it should be corrected once I disconnect the battery and install the fuse box, am I correct? or would I have to run a diagnostic to see if there are any codes and get the codes cleared if any any have occurred from relays I just switched?

BonitaBeast

No. Chances are you DID NOT mess anything up at all.....

Wait for the fuse box to arrive and install it and you should be good to go.

mo-shy

Hi there,

I think I have the same exact problem on my 03 G500. First,I took it to different mechanics whom did the same things that you have done with no luck one of them suggest the fan control module but we couldn't find it as a separate unit (I think it comes as part with the fan).

Finally I took it to expert Mercedes-Benz work shop. They told me I need new AC/ compressor, the AC bottle, recharge the AC and the sensor. This will solve the problem, and they said they need to perform AC radiator cleaning also ( I read this could affect the car temperature).

Honestly for me it doesn't make sense how does the AC compressor affect the fan working but the guy seems very confident about that!

Unfortunately I didn't have chance to repair it and I will not have chance to do the repair until next Dec since I am overseas now.

Please keep us updated.

BonitaBeast

Here's another pic that might help

victordakhteh

Well you were right about the deformation of the fuse box, same area of the fuse box on yours was also deformed on mine, however it hasn't led to fans working again, I guess this leaves me with taking it to the dealership, thanks again for your help, at least I caught the fuse box damage

BonitaBeast

There are two other relays that may have been damaged because of the damaged fuse box. Look in the above picture I posted where it says D and E. Left and Right aux Fan relay.

Let me look for the the matching picture so you see where the relays are located exactly. These are the relays located in the center console under the arm rest, from what I recall.

I still think you can avoid a trip to the dealership.

victordakhteh

Oh I know about the relays, if you remember earlier when I freaked out regarding the relays whether I messed it up or not, well I took them out without unhooking the battery and this is exactly what I did, I took the old relays out and put in new ones, and then I panicked when the relay felt a little warm and unplugged it while the engine was on, but then I stuck them back in. As of right now, when my car is on, the right aux fan relay feels warm and left doesn't, so again I don't know whats going on, other than that, the relays that are on right now are brand new and as you know so are fuses, I don't know if the relays are shot from what I did or not. For all I know, I am leaning on the possibility of the wiring being bad. Believe me if I could solve it myself without the dealership I would, I already have other expenses to attend to but its rough riding in this thing without cool air with help from the aux fans.

BonitaBeast

Yes I recall you mentioning the relays. One way you can do a quick check if the new relays were in fact damaged is if you interchange the two relays. If the same one gets warm even when switched to the other side then you know it's the relay. If the same side gets warm then you know it is possibly that side's wiring.

victordakhteh

And I should disconnect the battery while doing this yeah?

My uncle told me if I disconnect the battery I will lose the memory, what is he referring to? The error codes? And if so is that bad? I would think that those error codes would just come up again after being turned on.

mo-shy

Have you tried to check the fan aux relay behind the center console?

victordakhteh

Well this is embarrassing, I switched the wrong relays, I replaced the two black relays on the bottom row, Looks like I will have too get more relays incase I've screwed them all up.

victordakhteh

Sorry to hit you guys with all my questions, I just thought of some more in the last couple hours, one would be that what were the relays that I pulled out? And what that may have done, or possible fuses that need to be renewed cause of that since I'm guessing I may have blown out the fuses that those relays are responsible for.

mo-shy

This pdf has all the W463 components location. Since you have checked the left of dash board fuse with no luck. I would suggest that try to check the fan aux relay behind the center console. that I sent you the location above.