I wired mine in as shown on the instructions and it will not turn on the fan. The switch works,getting voltage on the output wire but the fan will not come on. Crazy. Cannot figure it out any ideas?
Great tip!! I'm doing a W126 280S "cooling modernization". I've bought the bigger aux fan (as you already have in yours) but I'm also considering in deleting the "viscous coupling fan" and/or replacing it with a electrical one. What do you think about it? It will save me some hp and mpg, as some say. I'm thinking in put it to kick in low speed at 92ºC and full speed at 95ºC. Thanks and congrats about the channel! Already subscribed!
Hi Rafael. I would leave the viscous fan alone. Another electric fan will put quite a load on your electric system. These old Benzes typically run 80C to 90C during regular year round driving. If they are getting close to the 100C mark then there is something wrong with one or more components. A failed thermostat typically fails open, but I have seen one that got jammed in a semi closed state. Make sure you viscous fan is working right; it should be difficult to move when cold and the engine not running. Whenever you start the car the fan should be spinning loudly for about 5 seconds at with the engine revving at higher speed. The water pump and radiator can also become a problem. Installing or using the existing aux fan is no rocket science and you can certainly do this, but I would address the root cause first. Otherwise you may just be delaying the inevitable catastrophe. I actually installed the switch because I converted the AC to R134a. The fan providing extra cooling in city traffic has made a huge difference, but the engine temp does run cooler also. Good luck.
what size is your condenser fan? does it fit on w124? both of my condenser fans not running, not sure why. Maybe the resistor? do you know where the resistor is?
The W126 fan(s) do not fit on W124. Did you connect the fan directly to a 12V power source? If they operate then it could potentially be the low speed resistor that typically sits near the fuse box near the fire wall. Another thing to check is jumpering the high coolant temp switch. That typically triggers the cooling aux fan to come on. Good luck.
@@straybenzes the resistor looked good. i need to test the fans. these fans are very hard to get them off. i am thinking getting the universal fans from ebay.
@@alanOHALAN Most of the cheap Made with pride in China stuff is not worth the money. All depends on how original you want to keep the car and how much you use it.
Hi! Awesome idea! I had to go out and get it myself... I’ve looked through the comments to try and see how you described the process. However I’m still having issues. A. My switch on the Benz has only two wires, and its blue and brown. The temp switch is constant closed till it opens. When you lift the plug off, the fans come on. I tested the temp such wire, and it has 5v ( is that correct?) You suggested tapping those two wires. But as long as they are connected to original temp switch they circuit would stay closed. Am i missing something? And lastly in action to the two wires tapped on the plug for temp switch and drawing another switched power from somewhere ?if so... where?
@@wolfgottlieb7737 Be careful as that is not a switch, but a sensor that goes directly to the climate control unit. The 91 350SDL is completely different from the wiring of the aux fan point of view. To get control voltage for the additional switch I would tie into the black/red wire of fuse 5 and use it to power the aux fan black/white wire. Hoping this will help you a bit.
Stray Benzes thanks, ordered mine yesterday, does it run the aux fan on high or low and does it switch between the fan speeds or just one all the time?
@@georgelynch6139 Hi there. This circuit is connected to the high speed only. Based on my humble observation the aux fan is helping the effectiveness of the AC condenser than helping significantly reduce the cooling water temp. The radiator and cooling system is significantly oversized and thus has plenty of reserve. Even an improperly working visco fan clutch typically will not cause much of an issue. When the temp gauge reaches >100C even on leisurely rides then start looking for other possible culprits: faulty sensor./ gauge/ wiring, head or block obstructed with rust or other foreign material, thermostat (although that is an odd one as they typically fail open meaning they cannot build up temp), air in the system (especially after working on the system). I only put the video up as there have been so many posts about the visco and aux fan that I wanted to demonstrate how a least intrusive and inexpensive solution would at least let everyone try this before having to diagnose the cooling system further. Good luck!
David Hurrell The power + comes from the switch that is normally activating it. I do not recommend wiring this straight to the battery since you would need a fuse and run the risk of draining your battery
@@Ralfweiser I did try that and I could not get the fan to work. The fan itself works fine as I've tested it with the battery. Any other suggestions on what I may be missing ?
David Hurrell Are you connecting from the three pronged water temp switch? You would need to pick up from the energized side. Before you do that I would jump hot and open to make sure the fan comes on that way. If it does not then you need to troubleshoot that first.
Thank you. I ordered the one with the bracket. 2 bucks more. This will buy me time until I feel like searching down the real issue. LOL
good luck
I wired mine in as shown on the instructions and it will not turn on the fan. The switch works,getting voltage on the output wire but the fan will not come on. Crazy. Cannot figure it out any ideas?
Does the fan run when wired directly to a 12VDC power source?
Great tip!! I'm doing a W126 280S "cooling modernization". I've bought the bigger aux fan (as you already have in yours) but I'm also considering in deleting the "viscous coupling fan" and/or replacing it with a electrical one. What do you think about it? It will save me some hp and mpg, as some say. I'm thinking in put it to kick in low speed at 92ºC and full speed at 95ºC. Thanks and congrats about the channel! Already subscribed!
Hi Rafael. I would leave the viscous fan alone. Another electric fan will put quite a load on your electric system. These old Benzes typically run 80C to 90C during regular year round driving. If they are getting close to the 100C mark then there is something wrong with one or more components. A failed thermostat typically fails open, but I have seen one that got jammed in a semi closed state. Make sure you viscous fan is working right; it should be difficult to move when cold and the engine not running. Whenever you start the car the fan should be spinning loudly for about 5 seconds at with the engine revving at higher speed. The water pump and radiator can also become a problem. Installing or using the existing aux fan is no rocket science and you can certainly do this, but I would address the root cause first. Otherwise you may just be delaying the inevitable catastrophe. I actually installed the switch because I converted the AC to R134a. The fan providing extra cooling in city traffic has made a huge difference, but the engine temp does run cooler also. Good luck.
what size is your condenser fan? does it fit on w124? both of my condenser fans not running, not sure why. Maybe the resistor? do you know where the resistor is?
The W126 fan(s) do not fit on W124. Did you connect the fan directly to a 12V power source? If they operate then it could potentially be the low speed resistor that typically sits near the fuse box near the fire wall.
Another thing to check is jumpering the high coolant temp switch. That typically triggers the cooling aux fan to come on. Good luck.
@@straybenzes the resistor looked good. i need to test the fans. these fans are very hard to get them off. i am thinking getting the universal fans from ebay.
@@alanOHALAN Most of the cheap Made with pride in China stuff is not worth the money. All depends on how original you want to keep the car and how much you use it.
Hi! Awesome idea! I had to go out and get it myself... I’ve looked through the comments to try and see how you described the process. However I’m still having issues. A. My switch on the Benz has only two wires, and its blue and brown. The temp switch is constant closed till it opens. When you lift the plug off, the fans come on. I tested the temp such wire, and it has 5v ( is that correct?) You suggested tapping those two wires. But as long as they are connected to original temp switch they circuit would stay closed. Am i missing something? And lastly in action to the two wires tapped on the plug for temp switch and drawing another switched power from somewhere ?if so... where?
Hi Wolf. That does not sound like the switch and wiring on the model in the video. What model and year is this?
Stray Benzes it’s a 1991 350sd with om603
@@wolfgottlieb7737 Be careful as that is not a switch, but a sensor that goes directly to the climate control unit. The 91 350SDL is completely different from the wiring of the aux fan point of view. To get control voltage for the additional switch I would tie into the black/red wire of fuse 5 and use it to power the aux fan black/white wire. Hoping this will help you a bit.
I hope you found a way to seal off that thermostatic switch. It will not do well out in the open like that.
I thought so too, but this retrofit has lasted for over a year and even works after pressure washing it. I am impressed it does work the way it does.
@@straybenzes Sounds like the switch may have some good o-ring seals in it. Zer good!
Are you splicing into the 2 wires or just cutting and eliminating the oem thermo switch?
I did indeed connect to the existing wiring as I did not want to mess up the basic functionality of the high engine temp switch function. Good luck!
Stray Benzes thanks, ordered mine yesterday, does it run the aux fan on high or low and does it switch between the fan speeds or just one all the time?
@@georgelynch6139 Hi there. This circuit is connected to the high speed only. Based on my humble observation the aux fan is helping the effectiveness of the AC condenser than helping significantly reduce the cooling water temp.
The radiator and cooling system is significantly oversized and thus has plenty of reserve. Even an improperly working visco fan clutch typically will not cause much of an issue. When the temp gauge reaches >100C even on leisurely rides then start looking for other possible culprits: faulty sensor./ gauge/ wiring, head or block obstructed with rust or other foreign material, thermostat (although that is an odd one as they typically fail open meaning they cannot build up temp), air in the system (especially after working on the system). I only put the video up as there have been so many posts about the visco and aux fan that I wanted to demonstrate how a least intrusive and inexpensive solution would at least let everyone try this before having to diagnose the cooling system further. Good luck!
Here is the link to where you can obtain the switch: www.amazon.com/gp/product/B01E52O5DG/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
The aux fan can help with engine cooling, but it is not a be all end all cure for high abnormal engine temperatures.
Link to where you bought please.
www.amazon.com/gp/product/B01E52O5DG/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
What radiator do you have? In there...
Hi there. It is a Liland Global all aluminum radiator. Here is a video that also shows the part number for the 300SDL
Did you take the power directly from the battery or from somewhere else ? Trying to do the same on mine.
David Hurrell The power + comes from the switch that is normally activating it. I do not recommend wiring this straight to the battery since you would need a fuse and run the risk of draining your battery
@@Ralfweiser I did try that and I could not get the fan to work. The fan itself works fine as I've tested it with the battery. Any other suggestions on what I may be missing ?
David Hurrell Are you connecting from the three pronged water temp switch? You would need to pick up from the energized side. Before you do that I would jump hot and open to make sure the fan comes on that way. If it does not then you need to troubleshoot that first.
@@davidhurrell286 The wire you need to take power from up at the coolant switch is the solid brown one. Good luck.
@@straybenzes thank you. I will try this tomorrow when it stops raining. Many thanks for your help.