Ok, riddle this one out. No aux fan, temp runs up to the next bar above 80. (90 or 100?). Aux fan installed and running, temp goes to *above* that.
Figured the a/c condenser was causing heat soak, turned off a/c system. No difference. WTH?
Why would the car run hotter with the fan in place? It can't be blocking that much of the radiator, and I moved the horns just in case. There is plenty of air being pushed through the condenser and radiator (checked with the aux fan running, but the engine turned off) so I can't figure why it would run hotter *now* than it did with the fan removed.
Next step is to do flush and fill, but this really surprised me.
Vehicle: 1985 500SEC, 1991 190E 2.6 (50k original miles)
Location: Los Angeles
Posts: 9,578
RE: Arggh! Aux fan woes
I have seen posts re. aux/electric fans before on benzworld. Living in a similar climate, I can understand what you are trying to do. It should be impossible for your car to get hotter while additional air is being forced through the radiator. It would be nice if you could put this problem to someone of Adrian Newey's caliber. Are you sure the fan and the blades are correctly installed and that air moves in the right direction? Does the fan get turned on at the right temp? Good luck, Horst K
Another caution is to NOT rely on the gauge in the dash alone. Poor electrical connections, especially at ground, can influence certain electrical devices when the demand changes on the system. I had a glitch that manifested itself every time I used my left turn signal. The oil pressure and temp, as well as the fuel gauge, would increase with each signal pulse. A quick cleaning of the ground(s) solved this problem. You temp gauge, if you are relying on the one in the dash, may be lying to you and moving upscale with the change in electrical load imposed by the fan.
Just a thought.
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RM Smith
Where is it again that we are going... And why are we in a handbasket?
I have seen posts re. aux/electric fans before on benzworld. Living in a similar climate, I can understand what you are trying to do. It should be impossible for your car to get hotter while additional air is being forced through the radiator. It would be nice if you could put this problem to someone of Adrian Newey's caliber. Are you sure the fan and the blades are correctly installed and that air moves in the right direction? Does the fan get turned on at the right temp? Good luck, Horst K
Yup. Its the original OEM fan, though I did try with an aftermarket 16" as well. My problem is that someone had ripped out the control stuff for the fan, and I pulled it out, as I thought it was dead. One aftermarket (flex-a-lite VSC) controller later, I found out differently. I had the same issue with both fans, and they are pushing a lot of air into the engine compartment.
I'm wondering about using a mechanical temp gauge from the old water temp sender for the aux fan, and seeing if it is indeed getting as warm as the dash gauge says. Does anybody know of a compatabile aftermarket mechanical that will fit the pitch of the OEM sender?
I've cleaned the temp sender, and used dieletric, so I don't think its a bad ground problem, and all of the fuses have been replaced. I'll check the dash ground the next time I pull the IP.
Hey Glenn! Remember, I just fixed this problem on mine a few months ago. (well, kinda the same problem) My new fan clutch was pulling lots of air and my A/C would run without the aux fan coming on! (?) Turns out the problem was my thermostat as it was restricting water flow into the radiator and showing "hot" on the guage. Because there was "still" water in the radiator, the fan was basically cooling the condensor, thus the aux fan never had to come on. I also changed the guage's sending unit, since it was cheap. (around $30)
Try changing the thermostat and maybe the sending unit to the guage, and see what happens from there. Call me if ya need any help/advice.[8D]
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"Imagination is more important than knowledge"
This might sound odd and with the summer months coming I was experimenting with my own 300se with heat issues. I had done everything including making sure the head and block were clean and all the electricalls in order. I did this one thing and it worked great and we'll see this summer. Look at going to 60/40 ratio on your Mercedes Coolant. 60% water and 40%c coolant. Yes, I did everything from clutch, thermo, radiator and the list goes on and on.
Try this and see. Doesn't hurt and heck you can go back.
Hey Glenn! Remember, I just fixed this problem on mine a few months ago. (well, kinda the same problem) My new fan clutch was pulling lots of air and my A/C would run without the aux fan coming on! (?) Turns out the problem was my thermostat as it was restricting water flow into the radiator and showing "hot" on the guage. Because there was "still" water in the radiator, the fan was basically cooling the condensor, thus the aux fan never had to come on. I also changed the guage's sending unit, since it was cheap. (around $30)
Try changing the thermostat and maybe the sending unit to the guage, and see what happens from there. Call me if ya need any help/advice.[8D]
I'll be replacing the thermo and coolent mixture and see how that works. Its got evil green stuff it in from the previous owner. Suspect it can't deal with the extra heat from the a/c condenser. I've heard people mention both 60/40 and 66/33 as the right mix for the MB factory coolant, so I'll try 66/33 and can always top off with MB red or Zerex if I think it'll improve. Anybody got an easy way to flush all of the old coolant - including the stuff in heater? And once it's full of 100% water, how to drain it completely and then refill with the correct mix?
Glenn, I would think that the easiest way to drain the cooling system is to disco one of the pumps outlet hoses. That way the pump does all the work and pumps out all the coolant/water. Anything left could be removed by the radiator drain or an engine block drain plug. (???)
Ok - spent this last weekend working with this, and as a result, had to miss the meet in Phoenix. Sorry Mike - but it started overheating and blowing water (Note - make sure you tighten the overflow to radiator when you are putting the t-stat housing back)
Temp climbs to right around 100c on the dash gauge, regardless of whether the a/c is on or not. Aux fan will kick on, and then the temp will drop to a little below 100c, but stay there even if I turn on the a/c. Have changed to an new 84c thermo, and used Zerex g5 (pep boys carries) in the cooling system.
Now here is the interesting part. Per members on the forum, 2/3 to 1/3 is the ratio of water to fluid. Per the instructions on the Zerez, its 2/3 fluid to 1/3 water. Have started with more water, as I can always drain and add more Zerex to increase the %. Will maintain this for 1 week and see if normal driving and temps stay constant.
Noticed when checking everything that the upper radiator hose doesn't seem to be terribly rigid when system is running. Is it normal to be able to have some give when pressurized? I'm not talking a lot, but I'm used to Chevy/Ford where you can't indent the rubber hose when its hot *at all*.
Have got the aftermarket fan controller working, but only on the thermo sensor. Need to figure out which wire to tape into on the a/c clutch/compresser to send a signal to the controller. The controller will take both neg and pos, I just have to know which one to use, so I can connect it correctly. The gentlemen at Flex-a-lite didn't want to guess whether its a positive ground or negative ground for the signal. Anybody know for certain which one it is, and which wire to tap into?
The other interesting thing is that the aftermarket says that its range is 155F to 220F. Its not kicking in till the dash gauge is running about 100c. I've thought about getting a simple mechanical gauge and putting it into the t-stat housing to see what the actual temp is, but have yet to find a gauge with the correct fitting for the temp sender threads. I'm guessing that the threads are metric coarse, and they are about 1/4". Again, anyone know for *certain* what it is? I've got the fans set for the lowest temp in the range, so it should be kicking in at 160f or so.
It seems the more I work with this, the more questions it raises. I want to make sure that everything with the controller and temp its activating at is resolved before any further troubleshooting - it may be that the gauge or sender is goobered, and I'm trying to fix a problem that doesn't really exist!
Glenn, I may need to help you out this weekend. To figure out the A/C clutch polarity, just use a test light. It can't hurt anything since a "short" will only light it up. Also, have you been to mb.braingears.com to find the schematics of your cars cooling system? Just remember the wire colors are in german! Call me this week if you can get out to my house and we can try to figure it out.
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