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Discussion Starter #1
About a month ago, in very cold weather, I started my car and the blower motor kept turning on and off. I could hear a loud "click" behind the dash panel and the recirculation button would flash on and off. After a few minutes it settled down and worked. A week later, it happened again, clicks and on and off and then the fan turned off. Stopped at a light, I turned the car off and on and the fan turned on without any further problems during that drive. It has happened a few times since, but this morning the fan was running, but blew cold air the whole time - lots of clicking again. The temps were good and normal, so its not a stuck open thermostat, and again, when I shut the car off and restarted, bang, warm air.

With all the clicking, is there some kind of relay switch behind the dash that may be causing the problem? I don't want to pull it apart without having some idea of what I'm looking for. Any ideas would be greatly appreciated.

Thanks!
Michael
 

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If you turn the climate control off, then on, do you hear the same clicking?

The interesting thing here is the recirculate switch flashing. That totally connects to the climate control unit and is something typical of main power totally being removed or restored to such a unit. (My thinking???)

I would pay attention to everything else electrical. See if anything else is going off/on when this happens.

And I would connect a voltmeter to the main power for the climate control system and monitor that. See if the main power for the climate control is going out or not.

If the main power to the climate control system is going out and coming back on, then the problem is elsewhere. But if it is staying on, then a problem with the climate control unit probably.
 

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Steve, you saying ACC board brings another thought to mind. I bought this car in August - 69,000 miles on it - and in October, the Tachometer stopped working. I understand that if the tach stops working and the air conditioning stopped working, it could be the Klima. I can't tell if the AC is working because its just so damn cold here in Chicago, but I'm wondering if the ACC board was causing problems, could this then shut down the AC and the tach? Just trying to pinpoint the problem.

I wasn't even going to try pulling the tach until spring when the weather is better, but what you said reminded me of this.

Whats your thoughts?

Thanks,
Michael
 

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Billy, when I leave work today I will turn it off and see if it still clicks. This morning it was the same thing. Click, off, Click, on, click off, restart car, everything comes on. Then it clicks some more.

Once the car warms up (interior) everything seems to be fine.

Thanks
Michael
 

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Billy, when I leave work today I will turn it off and see if it still clicks. This morning it was the same thing. Click, off, Click, on, click off, restart car...
What I was interested to know is if when it is working normally and you turn it off and then on, do you hear the same clicking sound that you hear when it shuts itself off?

The question is if that clicking sound is a part of the climate control system? Or if that clicking sound is coming from something else?
 

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What I was interested to know is if when it is working normally and you turn it off and then on, do you hear the same clicking sound that you hear when it shuts itself off?

The question is if that clicking sound is a part of the climate control system? Or if that clicking sound is coming from something else?
Oh, I understand now. No, this is not anything "normal". The clicking is coming from behind the climate control part of the dash. It is a loud "click", like a relay is overloading - turning on and off.

Michael
 

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Oh, I understand now. No, this is not anything "normal". The clicking is coming from behind the climate control part of the dash. It is a loud "click", like a relay is overloading - turning on and off.
OK, then possible that clicking noise is coming from something other than the climate control system.

There also is a multiple vacuum solenoid switch back there which directs the vacuum for various vents to open / close. Normally just one or two clicks on off and you don't hear that. I suppose all of them could be clicking on/off at the same time and thus making a loud noise?

That unit is located behind the lower right of the climate control unit. (Has lots of vacuum tubes connected to it.) You can remove the carpet panel on the right side of the center console (where left passenger's leg would be). Then drive with a passenger holding a tube to their ear and the other end pointed at that unit - see[hear] if the clicking is coming from that.

And all of those might click if the climate control system lost its main power and then power was restored (like the recirculation button flashing).

Or possible the climate control unit is going nuts, but best to be sure it is not losing its power first.

That vacuum switch looks like this...
 

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Steve, you saying ACC board brings another thought to mind. I bought this car in August - 69,000 miles on it - and in October, the Tachometer stopped working. I understand that if the tach stops working and the air conditioning stopped working, it could be the Klima. I can't tell if the AC is working because its just so damn cold here in Chicago, but I'm wondering if the ACC board was causing problems, could this then shut down the AC and the tach? Just trying to pinpoint the problem.

I wasn't even going to try pulling the tach until spring when the weather is better, but what you said reminded me of this.

Whats your thoughts?

Thanks,
Michael

Not so sure about the tach and the KLIMA corelation. I don't see any connections shown on the schematics between the ACC and tach. But cold weather will make bad solder joints act worse. The pushbuttons are soldered direct to the circuit board, so every time you press a button you stress and move the solder joint somewhat. When I bought my '88 ten years ago, I soldered the ACC switches, replaced the 30A strip fuse under the hood, replaced the brushes in the blower fan motor, replaced the small air sampler motor (aspirator) beside the glove box, and replaced the guts of the mono valve. After that the system behaved like it should. The PO had replaced some of the vacuum pods. Last year the rest were replaced.

I've read that others have had some electrical grounding issues behind the dash? Maybe chase that one for a bit, to look for loose / poor grounds.

And the recirc light comes from the ACC. So that's a common theme.

Good luck. No heat in cold weather is awful.
 

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okay...here's where I'm at.

Billy, you were right, its the same "clicking" noise that the Climate Control Wheel makes. Exactly the same.

If I hit the "O" button, it does shut everything down and the clicking stops till I push one of the other buttons, calling for the blower motor.

And now, I'm just not getting heat. The temp is good on the gauge. I've checked fluid level and its topped off. If I turn the car off and on, I get heat, but now it goes back cold after an indeterminate amount of time. Turn the car off and on again and voila! Heat.

I see on top of the thermostat housing, a couple of what I assume are sending switches of some sort. Just wondering if this could be a potential problem.

Is it possible the climate control module (if thats what you call it) is bad?

I'm a little lost right now. Any help, as always, greatly appreciated.

Michael
 

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Yeah, I think thats what I will do. Thanks for the help and I will post back with the results.



Michael


6 years later. Do you recall how you solved your problem, or if you did?

I’m investigating this strange same behavior in my 1986 300se (euro).

Here’s a video. I never investigated it before, assuming that low coolant levels could be the problem. Now I’ve fixed the coolant issue, and it seems to persist. Here’s a video.

I watched a Pierre Hedary video that suggests it may be the mono valve.




EDIT:
I have pulled the ashtray and console because I thought the clicking was coming from under the console or radio, but bow I can see that it must be coming from the control unit.
 

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I replaced the control unit above the radio (in the wood, includes the fan switch buttons, horizontal buttons and the temperature roller), and now the fan seems to be working correctly. So it seems the clicking problem can be resolved by replacing the dash control unit. I kept the same buttons that were above: recirc, hazards, defrost, etc and the wood too. It was just the one item in the wood that needed to be replaced.

If the problem recurs, I will report back.

OT: My AC compressor briefly ran the other day when I charged up the AC system to try and get cold AC after fixing my coolant problem. It won't run now though. It was blowing the white fuses. So I put a red one in. I wonder if I have a short somewhere. I put another white fuse in, and it looked like it was going to blow it. So I just swapped it again for a red. I know this is not cool, but the car is not being driven now. I will try to figure out what is going on with the AC compressor and that fuse. Another crazy item about this car is that the blower motor fuse tab was completely broken off. I got a fuse in there slanted for now. All of this is OT, but worth mentioning because I had the control unit problem.
 

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Fonzi, Are you talking about the fuse for the blower motor or for the compressor clutch? I may have misunderstood.

My original blower motor fuse holder had been disconnected (but it still looked in service to my newbie eyes) by the PO and reinstalled with a thermal fuse UNDER the fuse box panel, so I did not know this. My symptom was that the blower motor would cut out during a drive. It would the come on for the next drive for a few minutes, then cut out again. This would only happen with AC, not heat and I don't know why since the blower is on its own circuit. I would check the fuse which unbeknownst to me was fine because it was disconnected, yet why would it come on over and over. I finally got smart, after installing a new blower motor and having the same problem, and pulled up the fuse panel, discovered the thermal fuse, removed that and installed a new fuse holder and normal fuse for the blower motor circuit outside the fuse box. This has worked for a few months now with no cut out.

Sorry if that has nothing to do with your issue, but I thought it important to pass it on...good luck!
 

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Fonzi, Are you talking about the fuse for the blower motor or for the compressor clutch? I may have misunderstood.

!


Thanks for the reply. I posted in this thread because the original symptoms sounded similar. So I posted a video of my issue. Then I (pretty quickly) solved the issue of the blower motor not working.

I have other issues with my climate control now, which may or may not be related to the blower motor cut out issue my 300se was having:

- AC clutch not engaging. ??? The hvac panel didn’t seem to make a difference as the clutch wasn’t spinning this morning when I took video before replacing the panel (above the radio). The AC clutch engaged when I started charging the system with r134 a few days ago.

- the fuse panel is messed up, and one keeps keeps burning out with the white ones. I’m not sure it stops anything from functioning. So maybe I should try leaving it out.


Anyway, I’m good for now. I won’t touch the car for a few days.

Thanks!


Sent from my iPhone using Tapatalk
 

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This thread could come to another rescue! Or maybe I need to start a new one.

My 1986 420 SEL started the exact same blower on/off and clicking issue. It seems to be temperature related. Above 40 degrees everything works fine. Between about 32 and 40 it clicks on and off with a loud clicking noise coming from the control unit. Recirc light comes on and off simultaneously. There is heat radiating from the vents so the heat source, coolant etc is good. After running about 15 miles or so I can shut the car off, restart it and blower comes on as normal. Here I'm guessing the the little residual heat is enough to cure whatever is the cause? But I'm guessing. Lose or broken solder joints seems like a reasonable cause, especially with the association with temperature.

I sent the control unit to Programme. If nothing else as a long term maintenance repair. They told me this is common for this car but did not gauranntee that this is the only problem. Fair enough.

Installed the refurbished unit and it works great. Despite winter in WI, our December temperature is above 40 degrees! Today it got back to about 32 degrees.

No blower at all. Not even after running for 30 minutes - trip home from work. Today I will bring it inside and check the fuses and let it warm up to maybe verify again that this is temp related.

Where can I get a wiring diagram for the climate control?
Is there a sensor of some type that prevents the blower from coming on below a set temp? If so where is it?

Joe from Programma suggest a blower regulator. Where would that be located?

Any help is appreciated.
Jim
 

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There is what we often call the porcupine resistor that controls the fan. It's been a while, I sold my spares so can't show you a picture. Anyway from memory it's up in that general area where the blower lives. Remove the blower and look there I would. Sorry I can't be more specific.
 
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