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Discussion Starter #1
Hi Benz Guys.

Long time no talk. Haven’t posted anything recently as I’ve been busier than usual with work and everything with my S500 has been working as it should. Going on 253,000 miles and she’s still going strong. Or so I thought....

A few days ago while at work, I got in the car after it had been sitting outside all day and the interior was naturally very warm. I started the car and expected the climate control to kick in right away as I always just leave it on Auto at a comfy 72 degrees. Well to my surprise, the climate control never came on. I can adjust the temperature setting, adjust fan speed up/down and the displays will adjust accordingly but the fans won’t turn on. The AC compressor is turning either. I drove home with the sunroof open to cool off. The next morning, I got in the car and it was 48 degrees outside so naturally I was looking forward to heater warming up the interior as I drove my kids to school. Manual mode, Auto mode....absolutely nothing. After dropping off my second child at school, I was midway along my route to work when, unexpectedly the heater kicked turned ON! I adjusted the temp, tested the AC and everything worked again perfectly. Later that day, I took a colleague to lunch and...you guessed it. It stopped working again. On my way home that evening it worked again. So this issue has been intermittent all week. Then the other day I noticed that the EC light is illuminated, like I had turned off the AC by pressing the EC button. It won’t turn off no matter what climate mode I try switching to.

I know somebody had probably run in to this before, so I’d be grateful for any input you can give me.


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Discussion Starter #2 (Edited)
Hi Benz Guys.

Long time no talk. Haven’t posted anything recently as I’ve been busier than usual with work and everything with my S500 has been working as it should. Going on 253,000 miles and she’s still going strong. Or so I thought....

A few days ago while at work, I got in the car after it had been sitting outside all day and the interior was naturally very warm. I started the car and expected the climate control to kick in right away as I always just leave it on Auto at a comfy 72 degrees. Well to my surprise, the climate control never came on. I can adjust the temperature setting, adjust fan speed up/down and the displays will adjust accordingly but the fans won’t turn on. The AC compressor is turning either. I drove home with the sunroof open to cool off. The next morning, I got in the car and it was 48 degrees outside so naturally I was looking forward to heater warming up the interior as I drove my kids to school. Manual mode, Auto mode....absolutely nothing. After dropping off my second child at school, I was midway along my route to work when, unexpectedly the heater kicked turned ON! I adjusted the temp, tested the AC and everything worked again perfectly. Later that day, I took a colleague to lunch and...you guessed it. It stopped working again. On my way home that evening it worked again. So this issue has been intermittent all week. Then the other day I noticed that the EC light is illuminated, like I had turned off the AC by pressing the EC button. It won’t turn off no matter what climate mode I try switching to.

I know somebody had probably run in to this before, so I’d be grateful for any input you can give me.


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Just a quick update... I just watched a YouTube video on how to run diagnostic codes through the hidden Climate Control menu. I got 5 CODES! -sigh- They are the following: (KLA A) 1241, (KLA V) 1241, 1268, 1271. & 1452

I’ve done a few searches and the only thing I’ve been able to come up with is low refrigerant. From what I’ve read, that alone will cause the light to stay on and prevent my AC from working. Although that doesn’t explain why the heater doesn’t work.

I’m going to try and reset the codes to see if they go away or come back. I’ll report back with my findings.

Anybody with experience with this, please lend me your advice.


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Just a quick update... I just watched a YouTube video on how to run diagnostic codes through the hidden Climate Control menu. I got 5 CODES! -sigh- They are the following: (KLA A) 1241, (KLA V) 1241, 1268, 1271. & 1452

I’ve done a few searches and the only thing I’ve been able to come up with is low refrigerant. From what I’ve read, that alone will cause the light to stay on and prevent my AC from working. Although that doesn’t explain why the heater doesn’t work.

I’m going to try and reset the codes to see if they go away or come back. I’ll report back with my findings.

Anybody with experience with this, please lend me your advice.


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I had a similar situation a couple of years ago. The AC system of my 2004 S430 stopped working on the hottest day in L.A. regardless of my temperature and fan speed settings. Somehow it started working again the following morning, only to fail again in the afternoon. It turned out that the carbon brushes in the blower fan motor were worn out so the fan motor would intermittently fail. I tried all methods of cleaning the carbon brush contact area and it was still failing intermittently. So I finally did bite-the-bullet and bought a new replacement blower motor and it fixed problem. You can find detail procedures from YouTube on how to remove and reinstall the blower motor. Good luck!
 

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Also check the Blower Motor fuse, it's quite a hefty one, and they get bad connection and burn out the Contacts in the Fuse Box, caught early enough you can clean and tighten contacts carefully and install a new Fuse ;)
 

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Discussion Starter #5
...and so the process begins. Hey guys, thanks very much for taking the time to reply. I appreciate that very much. That certainly does give me a very good starting point. In addition to addressing both your suggestions, I’ll stop by the auto parts store and pick up a can of 134a refrigerant as well, since it appears the 1241 fault code has to do with low refrigerant. This should keep me busy for a little while this weekend....not that I needed another project, mind you. I have plenty of those to suck up what little spare time I have left these days. I’m sure you can relate.

I’ll keep you guys updated on my progress. Thanks for the tips.

I hope you guys have a great and car trouble free weekend!




I had a similar situation a couple of years ago. The AC system of my 2004 S430 stopped working on the hottest day in L.A. regardless of my temperature and fan speed settings. Somehow it started working again the following morning, only to fail again in the afternoon. It turned out that the carbon brushes in the blower fan motor were worn out so the fan motor would intermittently fail. I tried all methods of cleaning the carbon brush contact area and it was still failing intermittently. So I finally did bite-the-bullet and bought a new replacement blower motor and it fixed problem. You can find detail procedures from YouTube on how to remove and reinstall the blower motor. Good luck!
Also check the Blower Motor fuse, it's quite a hefty one, and they get bad connection and burn out the Contacts in the Fuse Box, caught early enough you can clean and tighten contacts carefully and install a new Fuse ;)

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Before I fixed my blower motor, I was getting those same codes too. After I replaced the motor and ran diagnostic thru the menu and they cleared themselves. The ac system has been working very well, heat or cold, since then.
So maybe you should hold off adding freon unless you know for sure the pressure is low and there is a leak somewhere. And BTW, beware of those low cost blower fans on eBay. They might not be properly balanced on the fan blades causing noise and vibration when running. Don't ask me how I know. 😖
 

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Discussion Starter #9
Walmart sells R-134A at a much lower cost than the auto parts stores. You want plain R-134A, not any with leak stop or any other additional chemicals, and ""synthetic" adds nothing.
Good morning Wally. Thanks for the suggestion. I stopped by Walmart on my way home from running errands yesterday and picked up a can of 134a. Since I don’t own a gauge I bought a can which came with one. Cool thing is there’s a $10 Core Fee. So I can just return the can empty when I’m done and get $10 bucks back.


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LOL that applies to most cheap parts on EBay !!
DOH! You mean like this one?
-sigh- Inherently I know that cheap parts on eBay are just that, cheap, but I was trying to avoid dropping $500 on this repair job, so I was about to make the same mistake you did. You busted me! Well...that settles it. I’ll just order the OEM part from FCP Euro. At least they offer a lifetime guarantee on the parts they sell.

By the way...did you replace only the blower motor or did you also have to replace the resistor/regulator?


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I haven't made the mistake of putting the Chinesium on my Car, but a colleague and I extensively did testing on all that rubbish a few years ago logging successes against failures / mileages/ DOA etc, you'd be surprised how awful that junk really is, or maybe not ;)

I always replace the both of them together ;)

You'll never know how good a decision that was :)

That Chinese piece of [email protected] in the photo would likely melt your wiring or similar, and that's if it actually even works right outta the box ..................

Incidentally, the box would be better quality than the part ;)
 

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Do you know which part is faulty? It appears that the regulator fails more often than the blower motor. You can quickly and easily test by unplugging the motor from the regulator and hooking it to 12 volts. You can usually find a working used regulator (not Chinese) on eBay, or perhaps from a local salvage yard.

If the problem is the blower motor, you can usually replace the brushes for a few dollars, or perhaps find a local auto electric shop - not a regular garage, not an auto parts store, but an auto electric shop that specializes in repairing/rebuilding starters, generators, alternators and motors.

I found a blower motor with attached regulator at my local pull-a-part for $22.50. It has been working for several years now.

$10 core charge on an empty R-134A can? Weird! You must be in California...
 

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By the way...did you replace only the blower motor or did you also have to replace the resistor/regulator?
I only replaced the blower fan motor. I checked the regulator which consisted of a few resistors, capacitors, and inductors. They all seemed okay to me and I was getting voltage to the motor terminals. In my case, it was the motor that failed. Depending on the stopping position of the motor from previous run, those worn out carbon brushes may or may not be making good contact with the rotor winding, hence the intermittent starting problem. Because when the motor was running, it would not fail. I even looked at replacing those carbon brushes myself but they were all riveted together & would have been quite messy. Guess my blower fan motor had seen better days after 140,000 miles. So EVENTUALLY I got a good replacement motor and it has been working flawlessly for 2+ years now.
 

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Discussion Starter #14
I haven't made the mistake of putting the Chinesium on my Car, but a colleague and I extensively did testing on all that rubbish a few years ago logging successes against failures / mileages/ DOA etc, you'd be surprised how awful that junk really is, or maybe not ;)

I always replace the both of them together ;)

You'll never know how good a decision that was :)

That Chinese piece of [email protected] in the photo would likely melt your wiring or similar, and that's if it actually even works right outta the box ..................

Incidentally, the box would be better quality than the part ;)
Wow! I hadn’t realized that people were having so many problems with the eBay parts. I figured they wouldn’t be built to the same level of quality as the German parts or use as high quality components, but little surprises like melting or shorting out my wiring is not something I had thought about. It’s just not worth it. So that said, fcpEuro sells the OE Mercedes blower for $211 + $69 for the regulator. The parts have a lifetime guarantee, so at least I can have the piece of mind knowing it will be the last blower/regulator I have to pay for should it ever fail again in the future.


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Do you know which part is faulty? It appears that the regulator fails more often than the blower motor. You can quickly and easily test by unplugging the motor from the regulator and hooking it to 12 volts. You can usually find a working used regulator (not Chinese) on eBay, or perhaps from a local salvage yard.

If the problem is the blower motor, you can usually replace the brushes for a few dollars, or perhaps find a local auto electric shop - not a regular garage, not an auto parts store, but an auto electric shop that specializes in repairing/rebuilding starters, generators, alternators and motors.

I found a blower motor with attached regulator at my local pull-a-part for $22.50. It has been working for several years now.

$10 core charge on an empty R-134A can? Weird! You must be in California...
Yes, you guessed it. I live in CA. I wonder how many people who bought a can of 134a and just pitched it in the recycle bin without knowing about the $10 buyback. It’s not much...but I’ll take it.

Since I had the can of 134a handy and no replacement blower motor to install, I decided to put a gauge on the low side AC line. Sure enough it was low, so I refilled the AC system until it was back in spec. I had to clear all the codes first in order to complete the procedure. Much to my surprise, the AC is blowing ice cold again, the blower is working fine and after driving the car all day yesterday running errands, I’m happy to report the codes haven’t come back and everything is working as it should. Just in time...we’re in for a hot week in the high 80’s, so hopefully everything holds up until the new parts arrive.


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I only replaced the blower fan motor. I checked the regulator which consisted of a few resistors, capacitors, and inductors. They all seemed okay to me and I was getting voltage to the motor terminals. In my case, it was the motor that failed. Depending on the stopping position of the motor from previous run, those worn out carbon brushes may or may not be making good contact with the rotor winding, hence the intermittent starting problem. Because when the motor was running, it would not fail. I even looked at replacing those carbon brushes myself but they were all riveted together & would have been quite messy. Guess my blower fan motor had seen better days after 140,000 miles. So EVENTUALLY I got a good replacement motor and it has been working flawlessly for 2+ years now.
Well if your carbon brushes were worn at 140,000 miles and needed replacement, at 253,000 miles I’m surprised my blower motor even works at this point. I guess I’m lucky in that regard. Everything needs to be replaced eventually and I think my blower motor is at the end of its service life. Hopefully it holds out until the replacement parts arrive though. It’s going to be a hot week in So Cal! Since clearing codes and recharging the system with 134a it seems to be working again.....for now.

I think your theory on the system working intermittently having to do with the carbon brushes being worn and where they stop each time I turn the car off makes the most sense to me. Thanks for your take on everything. I appreciate your insight and perspective.


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For all of you who get as far as removing a blower, if the copper part of the spinning armature which is contacted by the carbon brushes is not shiny, it should be. Lightly polish it with a mild abrasive typing eraser, if you can still find anybody who sells them. It looks like a fat wooden pencil, and sharpens the same way, to renew the point. I discovered this some 40 years ago. It cleans all electrical contacts, without grinding them down. Use this with relays, fuse box holders, and anywhere you need good electrical contact. My tool box goes nowhere without one or two of them.

It's also great with light bulb receptacles, and light bulb bases...after you turn the power off. And electrical plugs that don't seem to be making good contact. If the world stops making typing erasers, I'm in trouble.

I suspect worn out brushes are the most common cause of any older 12-volt D.C. motor of this type which has started to not work correctly. I have not had good luck getting them from MB, but any generic ones which fit and slide in the receptacle and can be wired in can be used.
 
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