Mercedes Aux Fans, Engine Cooling & Air Conditioning Explained, Coolant Sensor Tricks R129, W124 90s

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  • เผยแพร่เมื่อ 9 ธ.ค. 2024

ความคิดเห็น • 87

  • @dmorga1
    @dmorga1 ปีที่แล้ว +7

    As an R129 US spec SL320 owner, I really appreciate your videos. These things are brilliant references for years to come.

  • @syedshahid492
    @syedshahid492 7 หลายเดือนก่อน +3

    We greatly appreciate your knowledge about autos.

    • @HandyVal
      @HandyVal  7 หลายเดือนก่อน

      Thank you. More to come!

  • @markbaker6029
    @markbaker6029 4 หลายเดือนก่อน +1

    Excellent information Val - more I am learning from your videos!!! Blessings to you🙏

    • @HandyVal
      @HandyVal  3 หลายเดือนก่อน +1

      Thank you! This video covered, in my mind, so many important diagnostic details. Happy to have contributed to your R129. 😃

  • @BmwpetroldoorshoppingcarNordsc
    @BmwpetroldoorshoppingcarNordsc 7 หลายเดือนก่อน +2

    Fantastic video, top work. Explanation is perfect

    • @HandyVal
      @HandyVal  7 หลายเดือนก่อน

      Thank you.

  • @kalcine
    @kalcine 11 หลายเดือนก่อน +1

    Your explanation and DIY videos are pure gold !!! Thanks thanks a lot for them. I will try to add a 1k Ohm resistor to the blue overheating protection sensor (B10/8) hoping it will result the Stage 2 - Fans at High Speed - come on at about 95degrees Celsius. Greetings from Hungary where the summers are freaking hot.

    • @HandyVal
      @HandyVal  11 หลายเดือนก่อน +2

      Thanks for watching and leaving such a wonderful comment about my videos. The 1k Ohm resistor will work and will get those fans operating much sooner. I have never travelled to Hungary but know a few Hungarians in Canada. Its summers sound like those in Canada - hot!

  • @Hellblazzer
    @Hellblazzer ปีที่แล้ว +2

    Getting to know the resistance values of the "blue" ntc coolant sensor made my day. Thanks! I believe mine's faulty, because my fans are always working.
    Since I work with refrigeration, I was able to test the high pressure switch S32, it should close when higher than around 20bar (old type, red sensor) I believe. So, I believe my blue ntc sensor is bad. I hope, since it's probably cheaper than a relay.

    • @HandyVal
      @HandyVal  ปีที่แล้ว +3

      Glad it helped! The blue sensor is fairly cheap to replace and new ones are still available, whereas for the relays, new ones are much difficult to source but are available used.

    • @Hellblazzer
      @Hellblazzer ปีที่แล้ว +2

      @@HandyVal I tested mine a couple of hours ago, with the multimeter. It's "open", no resistance reading. So I'll have to replace it.
      Is there any special procedure on bleeding a 200e engine? Or is it as simple as letting it idle and topping up the coolant?
      Thanks once more, Your channel is very helpful!

    • @HandyVal
      @HandyVal  ปีที่แล้ว +1

      @@Hellblazzer You got it right by idling it and topping it off. There's also a little bolt on the thermostat that can help you bleed the system. I made a video on changing the coolant reservoir, where I provide some other tips on bleeding and coolant in general - although it's specific to the R129 engine it's also helpful in your situation.

    • @Hellblazzer
      @Hellblazzer ปีที่แล้ว +1

      @@HandyVal thank you very much! I'll give it a look.

  • @Rimvydas_Pocius
    @Rimvydas_Pocius 5 หลายเดือนก่อน +1

    Thank you Handy Val. Mine problem was bad pressure sensor and broken resistor. Now 2 stage fan working properly, but 1 stage not working. I will inform you later if I resolve a problem.

    • @HandyVal
      @HandyVal  5 หลายเดือนก่อน +1

      Great problem solving on making the Stage 2 work. The sensor and resistor do go bad. I hope you get the Stage 1 working too.

    • @Rimvydas_Pocius
      @Rimvydas_Pocius 5 หลายเดือนก่อน +1

      @@HandyVal I was mistake. I was looking wrong schematic. Mine W124 has K9 and K10 relay. So slow speed K10 relay trigger, then pressure switch is on. High speed K9 relay trigger, then temperature sensor reach impedance. So now aux fan working on both speed. Thank you Handy ;)

    • @HandyVal
      @HandyVal  5 หลายเดือนก่อน

      @@Rimvydas_Pocius Happy to see this sorted out. Helpful to clarify the different relays - thank you.

  • @williamkennedy5492
    @williamkennedy5492 ปีที่แล้ว +1

    I changed the thermostat and sensor both aux fans ran, put the old sensor back in all ok with fans ,, I am currently chasing a high idle rpm it sits at 1500 rpm, sometimes it drops back to 700 but for now its decided to sit high, any ideas would be really kind and useful and gratefully received. I tested the replacement thermostat and it didn't open !
    Best regards from high idle in Cheshire UK. where it rains a lot, no climate change here its always rains in the summer. I learnt a lot from you today and i am a very grateful Brit. I"m on a roll so will continue,
    I brought the car as a 50th birthday present for me, i am now 72 going on 73, its a great car but i stored it for 7 years , so have been changing a lot of items to make it roadworthy , Each year, once a car goes over three years we have to have a government test, ( they also do this in Thailand) and they are called MOT that stands for ministry of transport. My SL will fail on a rear brake pipe that i cannot get to, the MOT garage has agreed to replace, apart from that the car is in pretty good shape,
    I mentioned Thailand as that's where i retired to but am now back in the UK, My Thai wife does not want the car in Thailand possibly she thinks too many girls will want to jump in the front seat with me. She thinks the car is way too sexy and is a girl puller .
    Today she mellowed and said yes we can take it, I signed the car over to her 3 years back and she has to own it for 5 years to avoid Thai import tax and VAT which is a bastard of a tax too. The problem in Thailand will be the BIG SPIDERS and nasty snakes may just make my SL their home , i went toe to toe with a King Cobra three years ago , managed to whack it. I got lucky with a long handled shovel.
    In Thailand they drive on the left as we do so no probs there. The previous owner spent a great deal on the car as i have, and he also said it was the first one to be imported into the UK,
    For my sins i also own a W212 E class and that is a backside of a Mercedes, the rear subframe rotted out and Mercs replaced free of charge, Comparing the build quality of my 1989 SL to my 2013 E class the SL wins hands down every time.
    Anyway once again my thanks for this video and any news on a high rpm would be very welcome.

    • @HandyVal
      @HandyVal  ปีที่แล้ว +2

      William - The R129s don't like to be stored for too long. Using them, even sparingly, is typically the best preventive maintenance advice to give. There are two main culprits for a high and erratic idle: 1) Idle Control Valve and 2) Vacuum leaks. A dirty or malfunctioning idle control valve will give you all the symptoms you shared. It can be cleaned or replaced, depending on your budget. Cleaning may not always work. During the car's storage, this part might have seized. For vacuum leaks you want to check all the little vacuum tube lines (many visible with the hood open and filter boxes removed) and their rubber tubes/connectors - you are looking for anything that may be disconnected, brittle/broken or rotten. Rubber and those tubes, with or without use do deteriorate over time.
      Thanks for sharing your experience with the SL and Thailand! I agree with your view on the newer Mercedes - I too wonder how they'll hold up when then get to 30+ years of age. Keep us updated on the idle problem.

  • @fred613
    @fred613 10 หลายเดือนก่อน +2

    Very informative!! Thank you so much

    • @HandyVal
      @HandyVal  10 หลายเดือนก่อน +2

      Thank you. In this video, my goal was to take an important but confusing topic and try to make it more understandable.

  • @AlexAntoci007
    @AlexAntoci007 7 หลายเดือนก่อน +3

    good informative video

  • @peloponisios
    @peloponisios 6 หลายเดือนก่อน +1

    Thanks for the video! My issue is that only one of the fans is working on both low and high speed, should I assume that the other fan died?

    • @HandyVal
      @HandyVal  6 หลายเดือนก่อน +1

      Thanks for watching. Yes, the other fan has died, or it can be a broken connection. One fan on is always better than no fans on. It looks like the Mercedes engineers wanted at least one fan on because a basic electrical connection would imply that if one stopped working then it would break the electrical connection, so both would not work. Over-engineering wins this time!

    • @peloponisios
      @peloponisios 6 หลายเดือนก่อน +1

      @@HandyVal Thanks for replying

    • @peloponisios
      @peloponisios 6 หลายเดือนก่อน

      Now that you mention connection, I recently replaced the front bumper, hopefully I didn't forget to connect the fan 😀

    • @HandyVal
      @HandyVal  6 หลายเดือนก่อน

      @@peloponisios Yes. There’s a good chance a connection might have been missed.

  • @jackeywong6338
    @jackeywong6338 ปีที่แล้ว +1

    good to understand how the whole thing works. Going to do my test now. I suspect the low speed is not working on my W201

    • @HandyVal
      @HandyVal  ปีที่แล้ว +1

      Thank you. The video was inspired by questions I got on how the aux fans work. Let me know how your fans are testing.

    • @jackeywong6338
      @jackeywong6338 ปีที่แล้ว

      ​@@HandyVal Followed your instructions to by-pass the high pressure switch, both the crutch fan and auxiliary fans works. Tested the relay, it works as well. My car when stop in the traffic the air conditioner is not blowing cool air. Any further testing can be done? thank you

    • @jackeywong6338
      @jackeywong6338 ปีที่แล้ว

      Tested the temperature sensor on the head of the engine, without the engine is running, using multimeter. There is no reading between any of the 3 poles. I suppose it is a problem, am I right? But the clutch fan does run when the temperature reaches 100.

    • @HandyVal
      @HandyVal  ปีที่แล้ว

      @@jackeywong6338 Thanks for doing this testing. It looks like the AUX fans and relays are all doing their job well. Your problem with the AC not blowing hot air has to do with the refrigerant gas - it has likely leaked out of the system. You can buy a kit at an automotive store and that would repump new refrigerant into your AC. There are many TH-cam videos on this - it does not have to be specific to the R129. The kits are fairly cheap, but you need to ensure you got the right refrigerant as there are different varieties. If the high pressure switch is green, as in the video I shared then you can use R134 refrigerant. A mechanic shop won't charge much for this service as well, as it's easy and a max of 30 mins work time. I hope this helps.

    • @HandyVal
      @HandyVal  ปีที่แล้ว

      @@jackeywong6338 Sorry. I'm not following the 3 poles. Is this the blue sensor?

  • @MrLesiks
    @MrLesiks 2 หลายเดือนก่อน

    Hi, what about the 1994 sl 600. I heard that their operating temperature is higher. I'm constantly around 110 degrees. And I really don't like it. Is it possible to do the same with him?

    • @HandyVal
      @HandyVal  2 หลายเดือนก่อน +1

      The 600s can run hotter, but not by much. Is it 110C in stop and go traffic? Or is it at that temp at decent highway speeds too? The aux fans should come on just before 110C. Damage is done at 125C. So you’re close to it, but still have some safety. Make sure your aux fans are working, and then try a coolant refresh, and try the viscous fan test. When the car is off, can you free move the viscous fan? Or does it barely move. If it freely moves, then that’s likely your culprit. I hope this helps. Keep me informed.

  • @jamesclark6240
    @jamesclark6240 ปีที่แล้ว +2

    Very much appreciate your video Val. It is so helpful to know at least what components we are looking for! I have a 92 500SL and the fans do not come on when it is overheating.I replaced the thermostat but the old one checked out good anyway. I have wired around the S32 pressure switch and they will come on. I've check the B10/8 Sensor and it does get good readings. Does my jumping the leads around the S32 indicate that the R29 relay might be bad or the R15 resistor could be bad or both? My air conditioning has not worked in years and does not have coolant. Does that complicate the issue? Should the fans work with or without coolant in the system? Any thoughts?

    • @HandyVal
      @HandyVal  ปีที่แล้ว

      Thank you. Let's sort this out together. The overheating is hard to visibly test, as the car's coolant has to be in the 110 Celsius range and getting to that range can be hard - does your car get to this level and you don't get the aux fans turning on?
      By jumping round the S32 and having the fans turn on, means that the K9 relay is working and the fan connections\connectors work as they should. So your fans and the K9 relay are working. It could mean that the S32 is not functioning. The S32 is about protecting the AC - it's only one reason why your fans turn on. Since your AC is not working and has no gas, I would disregard going down the path of investigating or testing the S32. It doesn't matter for your situation as the S32 is about AC component cooling and not about engine cooling. Your worried about engine cooling, so I would focus on the B10/8 sensor and whether your car hits the temperature level required to turn the fans on. To trick the car into reaching temperature sooner, you can try adding a 1000 Ohm (1/4 watt) resistor to the B10/8 - just wrap the resistor wires around the two plugs of the B10/8 and put the wire plug back over it - and drive. You don't need to solder the resistor on. What this will do, is bring the temperature to a much more reasonable level (about 95 Celsius) to achieve, and your aux fans should turn on. The 1000Ohm resistors are very cheap. Let me know.
      Note: Whether you have AC gas in the system or not, it won't impact the engine cooling parts of the aux fans.

    • @jamesclark6240
      @jamesclark6240 ปีที่แล้ว +1

      Thank you again Val, so I have a dozen or so resisters on the way, think I will only need one,, haha, but that's how they sell them of course. In the mean time I was thinking why wouldn't jumping the connector at the B10/8 pins set the fans off the same as jumping them at the S32 connection? Essentially by putting the resister on the sensor lowers that threshold but if it gets to around the 250 or 300 mark and turns on the fan jumping them with a wire would send it to zero, shouldn't that make the fans run? I did try this but I get nothing? I suppose there could be a short in the wires somewhere, or could that mean the K9 relay on that side of the relay is not working? From the wiring diagram on the relay it looks to be two switches. Any thoughts? I did attempt to run it a little longer, a couple trips around the block but it did not go much above 85 deg. Nervous about taking it on a longer trip not knowing if it is going to overheat or not. @@HandyVal

    • @HandyVal
      @HandyVal  ปีที่แล้ว +2

      James. It seems intuitive that the jumping of the wires and bypassing the B10/8 altogether should turn the fans on, but they won’t. I think it’s because it’s measuring the change or a level of resistance and zero isn’t an option - it’s puzzling because the jumping works for the others. Hey, if you struggle to get the car’s temperature above 85C, you likely have a fine tuned R129 operating at its best. It’s really in the stop and go traffic(and I mean heavy city traffic where one moves 1km in 10 minutes) that the car’s temperature hits the 90s. The additional resistor will get the fans to turn on at around 95 instead of 105/110C.

    • @jamesclark6240
      @jamesclark6240 ปีที่แล้ว +1

      Thanks VAl, this has been so helpful, I have had to replace the fuel pumps/filter and accumulator as well as testing and cleaning the injectors it has been a real journey for me even though I have had this car close to 20 years now, I always took it into a shop for service, watching TH-cam videos has given me quite an education, the Benz fuel injection system was very state of the art back then. I am not a mechanic, but I was able to get it done. Thanks again for your help.@@HandyVal

  • @rioraton
    @rioraton ปีที่แล้ว +2

    Good stuff Val! I purchased what is called a "cool harness" it is resistor built into a fitting that goes on top of the 10/8 sensor. The wires then plug into this fitting. My resistor turns the fans on at 90c with or with out the air running. I live in the desert where temps on avg in june, july, august are 115-120F . Just driving to the store 12 miles away with only 1 stop sign my temps were running 100+c so it scared me and I bought this little unit 100 bucks for a .90 cent part. But it is worth it to me.

    • @HandyVal
      @HandyVal  ปีที่แล้ว +1

      Thank you. You did the smart and right thing by adding a resistor and having the fans turn on at lower temperatures. Your engine will thank you by lasting much much longer than it otherwise would without expensive rebuilds. Anything over 100C for a prolonged and recurring period isn't engine healthy, even though some versions of the SL's operating manual does say it's the red zone on the temperature gauge that needs to be avoided. I haven't experience those outside temperatures you have yet, but in my summer months (outside temps 30C/90F) my SL's temperature easily sees the 95C (not quite 100C) in city stop and go traffic (where you move 1km/0.6miles every 5 mins), whereas on the highway it's in the mid to high 80C range (85-89), not quite 90. I will mostly likely use the resistor trick too. Thanks for sharing.

  • @ministryofengineering3850
    @ministryofengineering3850 2 หลายเดือนก่อน

    Hi Val, another great video. Can I seek your advice? I took my pristine R129 (1995) SL320 to a supposedly reputable garage, asking for an oil and filter change, a change of coolant, and a new thermostat. I collected the car and drove home some 3km. I opened the bonnet and found they forgot to replace the coolant cap. I complained, and they apologized. Yesterday, I took the car out, and it hit 100C in stop-start traffic; usually, before they worked on it, the car would never rise above 90 C regardless of traffic. I took it back to the garage, and they added more coolant, a liter; it seems they did not bleed the system properly. Still, after this the the temp is hitting 100 C in traffic. Have they damaged my engine? Why does the temperature increase when heavy stops start traffic? The fan kicks on ok, but this change after they did their work is worrying.

    • @HandyVal
      @HandyVal  2 หลายเดือนก่อน

      I’ll try to help as much as possible. The good thing is that 100C is a reasonable temperature in stop and go traffic. No harm is being done to the engine. Damage is done at about 120. I’d be worried at about 110. Good news is that your aux fans are working. Also, you travelled a short distance before realizing the lid was missing and the coolant needed a top-up…again no damage could have been possible. So good news.
      Now to solve why it’s going to 100, when previously it was 90. Can you ensure the lid they used was yours? And not a random one from another car manufacturer? Those lids are meant to keep a certain pressure, and are marked for a certain pressure, typically it’s 140KPA but do a search for your car. Keeping the system pressurized properly keeps the car cooled properly. Second what thermostat did they put in? Those thermostats have temperature ratings too. Original specs from Mercedes is 87C. So when the coolant temperature reaches above 87, then the coolant is circulated around the engine. The thermostat they put in
      Might have been a different spec, and so you get different temperatures. Does the temperature begin to fall once it reaches 100C?
      It could also be a faulty thermostat. It can happen, and may be worth a replacement.

    • @ministryofengineering3850
      @ministryofengineering3850 2 หลายเดือนก่อน +1

      @@HandyVal@HandyVal Thanks, Val, well. I watched your video on replacing the header tank and followed the instructions to help bleed the system. I had the heater on full temp and drove up and down some hills. That seems to have cured it, and the car is back to running at normal temperatures, even after a good blast on an autobahn and the straight into stop-start traffic she stayed in the high nineties. Normal driving she is back to 84C, thanks again.

    • @HandyVal
      @HandyVal  2 หลายเดือนก่อน +1

      Excellent news! Great to know the car is back to normal. Happy to have helped. 😃

  • @joe5087
    @joe5087 4 หลายเดือนก่อน

    Thanks for the video. So the thing about mine is that when I turn the AC on in a stand still the center vents won’t blow. The stage 1 fan does not turn on either.
    I’m wondering if it’s the resistor that’s causing the AC not to turn on in the center part of the car or if the AC not turning on in the center vents causes the auxiliary fans not to work since the AC isn’t really working when I’m standing still.
    The AC works completely when I’m driving but not standing still.
    Thanks for the video. I hope you understand what I’m saying haha. I believe the stage 2 is the only thing working. It kicks in after a while of the car being on.

    • @joe5087
      @joe5087 4 หลายเดือนก่อน

      I just took the headlight on. I actually don’t see that part you have. I have a 1995 sl320 r129

    • @HandyVal
      @HandyVal  4 หลายเดือนก่อน

      Thanks for the question. The resistor wouldn't cause the center part vents to not work. When you press the AC/heater buttons (vents, center, feet vents, etc), there is a part behind the dash that controls where the heat is directed. It seems like that control may be broken. It's common, but I wouldn't sweat it, as long as the car cools and heats, and your comfortable.
      Are you saying the AC doesn't work when the car is stopped in traffic, or with the car in P (park)?

    • @joe5087
      @joe5087 4 หลายเดือนก่อน

      @@HandyVal thanks for the response!!
      both when I’m stopped at a light and when I’m in park. It opens up again when I start driving.
      I think the AC works the whole time but the center vent closes up when I’m stopped or parked.

    • @joe5087
      @joe5087 4 หลายเดือนก่อน

      I’m just also worried because my engine gets pretty hot. It only cools when I’m driving too. I don’t think the fans are working in stage 1 at all

    • @HandyVal
      @HandyVal  4 หลายเดือนก่อน

      Let’s try to solve this. What is the engine temperature you’re experiencing?

  • @arnoldboth3253
    @arnoldboth3253 10 หลายเดือนก่อน

    Thanks for the video Val ! My problem on the S320 W140 is the aux fans stays on even when the ignition is off. Maybe do you have an idea what causes this ?

    • @HandyVal
      @HandyVal  10 หลายเดือนก่อน

      Thanks for watching. Let’s diagnose this problem of yours. This is likely your engine harness. I believe your car has the biodegradable wiring harness and this could be one of many symptoms of a bad harness. Does your car have other problems? Do you know if your harness was ever replaced? It’s costly so let’s try some simple things first: for the items shown in the video, notably the blue sensor remove the connector, clean the contact pins and pinholes with a light sandpaper scuff and then a spray of contacted cleaner. You could also try replacing the blue sensor - they are cheap to buy.
      I think in your version of 320 by removing the connector on the blue your aux fans come on, so it could be a bad blue sensor or a bad connection. Keep me updated.

    • @arnoldboth3253
      @arnoldboth3253 10 หลายเดือนก่อน +1

      Thanks for the quick response! I’ll keep you updated.

  • @wonderties
    @wonderties ปีที่แล้ว

    Hi Val, R129 SL500 fans turn on at stage 2 when I turn on the engine and fans shut off
    when I turn off the engine.

    • @HandyVal
      @HandyVal  ปีที่แล้ว +1

      Thanks for the comment. The stage 2 fans shouldn’t come on as soon as you turn the engine on. It seems like a previous owner/mechanic might have modified the fans to turn on all the time. If they were never coming on, then there’s reason to worry. What temperature do you typically see in stop and go traffic or after a 1+ hour drive? Can you see a resistor on the tab connecting to the blue coolant sensor?

  • @hugojorge4572
    @hugojorge4572 5 หลายเดือนก่อน

    Hello!! I have an SL 320 and its overheating. I’ve been checking and the aux fans dont come on unless ac or heating is on. But what is most weird is that if my car is on, and I unplug the blue sensor (the coolant one) they start working stage 2 just being unplugged. Is that normal? What could be wrong? Thank you!

    • @HandyVal
      @HandyVal  4 หลายเดือนก่อน

      Is this the 93 to 98 SL320? I think so but please confirm. Removing the connector in the 320 will turn the fans on. So in your car everything seems to work so the sensor may be in question. Remember in normal course, the coolant temperature has to be in excess of about 107 Celsius, so hard to test, as it’s difficult to get the coolant temperature that high. Is your temperature that high? Since the blue sensor is cheap, you can simply replace it.

    • @hugojorge4572
      @hugojorge4572 4 หลายเดือนก่อน

      @@HandyVal hello!! Yes its a november 93 SL 320 104.991. Yes it gets that hot, it almost got to 120 once. Spain is around 40 degrees around this time of the year.
      The only way to get the temperature down is by turning the heating on that way I wont ruin the engine.
      I tested the sensor yesterday, and it was 1300 that made sense with the coolant temperature.
      I only see that aux fan speed when I unplug the sensor or a bit slower if AC is on.
      Im also worried about the mechanical fan, as Ive read that if the car is cold and you try to move it, it will offer a bit of resistance, but if the car is already hot, it would have to be harder to move. Mine offers the same amount of resistance (its not loose) hot or cold.
      Coolant is new, and doesnt look dirty.
      Any ideas?
      Thank you very much for everything, you’re the best!!

  • @razmadzekoko
    @razmadzekoko 8 หลายเดือนก่อน

    when you take off the cap conector of blue sensor and when the engine is on, should auxiliary fan turn on automatically with the high speed?

    • @HandyVal
      @HandyVal  8 หลายเดือนก่อน

      They should not turn on. It seems logical that they should, but they don’t. Are your fans turning on?

    • @razmadzekoko
      @razmadzekoko 8 หลายเดือนก่อน

      @@HandyVal one mechanic told me they should be turning on, I tested and they several times it turned one once, but most of the time they dont. I am curious what is going on.

    • @HandyVal
      @HandyVal  8 หลายเดือนก่อน

      On some Mercedes models it does turn on when unplugged if the ignition is on. However not on the R129, as it’s set up differently. I think what happened to you, on the one instance they turned on, was that the friction of removing the plug tricked the resistance level to change within specs and that caused the fans to turn on. What model of R129 do you have?

    • @razmadzekoko
      @razmadzekoko 8 หลายเดือนก่อน

      @@HandyVal I have w126 (1989 year model) but it has m103 engine like yours, so most of the things around the engine is the same. Does outside temperature plays some role in that stage too?

    • @HandyVal
      @HandyVal  8 หลายเดือนก่อน

      For your model the fans will not engage if you unplug the blue sensor. The outside air temperature only plays a part for the low setting of the fans. The low setting does not use the blue sensor. So for your issue, the outside temp has nothing to do with it. How how hot does the car get in super slow traffic. I’d only worry if it gets consistently above 100C

  • @troyferguson86
    @troyferguson86 4 หลายเดือนก่อน

    I want to buy a used Mercedes but the aux fan is stuck on high. Is this a major issue?

    • @HandyVal
      @HandyVal  4 หลายเดือนก่อน

      I don’t think it’s a major issue but the answer ultimately depends…If the fans are on high speed because the system is always super hot, then that’s a major problem and will likely need a coolant system overhaul. If it’s on, while the car is cool, then it’s likely a faulty sensor, which is cheap to replace.

  • @ascendantjustice1173
    @ascendantjustice1173 2 หลายเดือนก่อน +1

    Found out why my fans aren't working? I bought my car and it's missing the K9 relay entirely 😂😂

    • @HandyVal
      @HandyVal  2 หลายเดือนก่อน +1

      Happy to have helped!

    • @ascendantjustice1173
      @ascendantjustice1173 2 หลายเดือนก่อน +1

      Helped tremendously ​@@HandyVal
      Now the fans are working. I paid 800 for my 1995 SL320. Guy could t get it smogged because the EGR Valve was seized. Replaced that and then got it smogged, but I noticed the car was getting warm 105°c when I ran the AC and the fans weren't kicking in. Fixed the fans, changed my thermostat, changed clutch fan, flushed rad and changed the coolant and ran water wetter in it, and now I can run the car with AC on 4 in 104° F weather at idle and the car won't exceed 95°C

    • @HandyVal
      @HandyVal  2 หลายเดือนก่อน +1

      That’s an amazing deal. And with a little bit work, you now have a car operating like new. And oh, it’s an R129 - a super cool car. It’s win-win-win!