A/C and Heat - PeachParts Mercedes-Benz Forum

iwrock · #1 12-31-2004, 12:02 AM

Ok all. I have a problem with my 400E heating and cooling system. This problem only started to happen this morning. I went outside, and started her up. Fired up, no problem at all. Then after letting her warm up for a few minutes, I left, and started driving as normal. I stopped at a stoplight, and pushed the button combo for heat. Nothing happened. After a few more minutes of driving around, I played around with the buttons. I then noticed that heat was coming out of the vents. However, there was a little pressure. It is doing the same thing with air conditioning. I came home, and parked it in my garage. I checked the fuses, and there is an external 15 amp fuse that is seperate from the box, and it goes to the ventilation system. This was blown, so I fixed that, however, there is still no heat, and there are no blown fuses in the fuse box.

Thank you in advance, Justin.

P.S. My father thinks that the car is getting back at me for parking her outside. This is the first time she has been left outside in the 2.5 years of ownership.

meltedpanda · #2 12-31-2004, 05:23 PM

if you are getting heating and cooling and the pushbutton unit and dials seem to work then I would look closely at the fan and any assoiciated fuses in the fan circuit. Power 12V to the fan and see if it works.
Also how many miles?
Could be worn fan brushes, can you start the fan by giving it a good jolt?

BenzMatic · #3 12-31-2004, 05:48 PM

The fuse you replaced is supposed to be for the blower fan motor. Is there any air blowing at all? cold or Hot.
Thanks

iwrock · #4 01-01-2005, 12:07 AM

Couple of answers.
1. She has 150,000 miles, and it could be time to replace the fan or brushes.
2. There is some air blowing, but only when the car is revved. (When driving or actually revving up the engine.)

Couple of questions.
1. Where is the fan?
2. Are there any other fuses in the fan circuit that could have blown out?

Once again, thank you.

meltedpanda · #5 01-01-2005, 08:05 PM

I would venture to guess you fan is toast, probably why the fuse was blown.
On mine it is under the dash above the passengers feet.

iwrock · #6 01-01-2005, 11:01 PM

I will go under the dash tommorrow. It is a little dark and I dont want to poke around in the dark. I will look, and see what I can do.

Heavy Dee · #7 01-02-2005, 03:53 AM

Hi,

I have a similar problem with my '92 500SEL. Cool air only comes out of the single vent on the driver's side and the vents between the windscreen and the dashboard. No air comes out of the front vents however, while the vents at the back (passenger cabin) work fine.

I wonder if this is a blower problem since air comes out on the driver's side and the vents behind. can anyone assist with what it may be please?

Thanks
Heavy Dee

BenzMatic · #8 01-02-2005, 02:42 PM

First of all welcome to the board, now to your problem. It is not clear from your post that you are on AC settings and cool air is not coming from all the vents or you are on Heat settings and expectign hot air from center vents. Anyways I will take a stab at both, If you expecting Hot hair rather than cool, if that is the case center vent are not suppose to have any air on Heat settings. Once heater settings, air only comes out of side vents, leg area and probabally from defrost vents.
If you are on AC (cool) settings and expecting the cold air from center vents, yes you are suppose to have that. In either case it does not look like you have a blower problem, since you are getting air from driver side vent and back vents. Most probably your pods (vacuum elements) are bad, these are the one which directs air by opening and closing the vents. Do a search for the board, you will find a lot of information on this topic, pretty comman issue with older Mercedes.

Hope it helps, Good luck

iwrock · #9 01-03-2005, 03:16 AM

There is air coming from the vents. It is hot when want it to be hot, and it is cold when I want it to be cold. However the problem is with the amount of air. There is barely any air being blown through the vents. It is like it is on economy, and it wont come off, no matter what buttons you push.

BenzMatic · #10 01-03-2005, 03:31 AM

I am assuming that air is coming out of when your car is not moving (means fan is working). The reason, I am putting so much emphasis on it, is that you can have bad fan but when you drive the car fresh air can come through and you will have hot or cold air but not enough. Here are couple of things to check.
1- When AC on and small amount of air coming from the vent, check for the defrost vents. Do you have a lot of air coming out of the defrost vents? If that is the case it is your vacuum element.
2- When fan set on high speed, do you hear the fan noise (usually loud). If not most probably you fan brushes are worn out.
3- Last but not least, your ACCU is bad. Might have bad solder joints.

4- Try applying direct 12V to the Fan motor to see if it runs on good speed and does air volume is good through the vents.

I hope this helps, keep us posted.
Thanks

iwrock · #11 01-04-2005, 01:44 AM

Ok. I am sorry if I was not clear. When the car is moving, air comes through vents, when not moving, no air at all. Car is Stopped=No Air... When the car is Moving=Minimal Air... I know that when it is moving, it is just air that happens to make it through the system, which would be why there is no air at all coming from the vents when stopped.

I am still waiting for a nice day to go at it, and see if the fan is dead or not. I am praying it isnt dead, but I am prepared for the worst.

Sorry for the fuzziness, The Wrocket

BenzMatic · #12 01-04-2005, 02:36 AM

Justin, It definately sounds like your blower motor (fan), most probally need to change the brushes. Very easy to do if you are inclind, another possibility could be your blower fan regulator.
Here is another idea, just a long shot before you start taking apart for the blower motor, to check the fuse again. I am not sure about your car but my car does have an extra fuse for the fan motor. It is not in the fuse box and it is in a black plastic box, it is a 30A strip fuse. You have replaced one external fue with a 15A, it is worth checking again. May be the fuse is blown again due to not proper value?
I hope you are keeping your car inside now, you do not want to have more problems

, these things are pretty touchy and sensitive.

Good luck and keep us posted

iwrock · #13 01-04-2005, 06:47 PM

I am going to definitely put another fuse in the external fuse holder. I was wondering though, If you have a 30 amp fuse, should I use a 30 amp fuse? And today looks like a nice day for hunting down the problem, because today, it is actually sunny. On my way home today, I will stop by napa and pick up more fuses. I will get some 30 amp fuses, but I will not try them unless I have 2 people say that it is a good idea. So I will put a new fuse in there to see if that is the problem. Also, does your external in line fuse box have a black base, with a clear lid? I just want to be sure that that is the fuse I should be changing. Thank, you Justin.

One more thing, did you get my name from my screen name? Or was it a wild guess? Let me know. Justin W

BenzMatic · #14 01-04-2005, 08:39 PM

It sound like we are not talking about the same fuse, which gives a hope here. The blower fuse is a in a small black box next to the fuse box against the firewall (at least that is where it is in my car), see attached pics for details. You just flip open the black box and inside there is an silver E shape strip held in place by two philip screws. This is a 30 Amp fuse, it is the same size for your car, I checked the Fast Lane (Part# p201584449, by Bosch, $0.60). I have a very strong feeling that this is your problem.

The attached pics are from my car W126 and not yours, but it should be around the same location. May be some one with W124 can confirm it, but it should give you a good idea what to look for.
Your name was very obivious in your first post, you signed it at the end of your post

I wish it was sunny

here, it is raining and cloudy

Good luck

iwrock · #15 01-06-2005, 02:16 AM

The strip fuse is fine. It is not blown at all. Just to be sure, I bought another one, and it is still disfunctional. Looks like my blower may be toast. I think that this is a job best left to my mechanic. I do not want to play around with the electronics in my car.

By the way, thanks for the pictures. I had no idea that there was a strip fuse. I believe I have now narrowed it down to a problem with the blower, and this is one area I fear to tread. I think that this is one of those problems best left to a mechanic. Thank you for your time, Justin.

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