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Discussion Starter · #2 ·
Alex, In mine I have 1 aux fan and it always come on when the AC is on, or when the engine gets VERY hot. My mech connected both the radiator and aux fan, so they both come on at the same time. Makes a lot of difference. If you have 2 aux fans, than one should always come on when the AC is on, and the second comes on when the engine overheats (I think...)
 

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Discussion Starter · #3 ·
How do you get both fans to come on at once in a 190D?

Hey piotr how do you get both to come on at the same time? I'd like to do that. Mine's been getting to 100C all the time now, and I like it to be between 80 and 100. Thanks.
 

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Re: How do you get both fans to come on at once in a 190D?

Well, first off your fans WILL NOT kick in before about 110C. If your temp gets to or over 100C while driving, it's time for a new radiator (I put in a Nissen for $200). temp between 95C and 105C in stop-and-go traffic is normal). BUT, if you want to have your temp to go down from 110C to 100C (that's the range in which fan switch operates)VERY quickly (about 10-15 seconds) just splice together positive wires from the switch (main fan wire plugs in to the top of the switch, and the aux plugs to the side of the main wire). just try it out. at worst you will blow the fuse).
 

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I do have a new radiator... Could it be my thermostat?

My radiator is a brand new behr that mercedes put in. My aux coolant pump is brand new as well. That's why I suspect the thermostat. It may not be opening fully.
 

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Re: I do have a new radiator... Could it be my thermostat?

I doubt it, but it won't hurt to check (or replace). Also check your coolant reservoir cap (rather-replace it). make sure your aux fan works (may be a blown fuse). When you splice wires-aux fan has a single wire on the side of the switch. you want to connect it to the blue wire (need to peel off the outer insulation)of the main fan. Finally, your temp sending unit may be bad.
 

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Re: I do have a new radiator... Could it be my thermostat?

Hmm I am on other mercedes forums as well. I am getting different opinions on what I should do. Most say I should replace the thermostat. They also say the fans do not come on unless the engine gets up to 110C. So that'd explain my fans not kicking in. I am not going to wire the fans together. I will wait a while longer and see what the car does, if it sticks around 100C I am not going to worry about it as this is still considered a safe operating temperature, and my grand cherokee operates at around the same temperature as well. It has the towing package which gives me a heavier duty cooling system and heavier duty transmission. So it definately has no cooling problems. Actually had it in for the 60k sevice and the coolant was fine even before they drained it.<br> <br> Thanks for the help Piotr. It's nice to have another 190D 2.2 person on here!
 

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Re: I do have a new radiator... Could it be my thermostat?

I hear Ya! You have no idea what I went through the first year had the car!! <br> Waiting is ok,and as I remember, you did change the expansion reservoir cap some time ago. My car goes all the way to 100C mark, but only touches it and stays below (the needle does not cover the mark). Splicing the wires (blue one from the main fan) will not hurt anything, but you don't have to do it. The only other problems making your car run hot that I'm aware of are :<br> timing<br> blown head gasket<br> tranni sticking<br> brakes biding.<br> All of the above have very characteristic symptoms, so you would know what's wrong. i think I listed for you all problems where running hot is the only indicator.
 

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Discussion Starter · #9 ·
Hmm.. well

Mercedes determined the engine was in perfect running condititon... so definately not the head gasket. I still suspect the termostat, they seem to die after a while, either they open to much or not enough, so it's either over cooling or under cooling. My needle covers the 100C mark. Could it even be the temp sensor or the needle? If so how hard are these to replace and the cost of them? Thanks piotr.
 

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Re: Hmm.. well

I replaced the heat sending unit (middle of the engine sidewall, driver side, you can see it through the break in the intake manifold), and then replaced it right back with the old one. The dealer sold me either a bad or incorrect unit.<br> <br> What you describe is identical to when my reservoir cap went bad. Sorry, that's allI know. New Thermostat is about $40.
 

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Discussion Starter · #11 ·
Re: Hmm.. well

The thermostat is 12 bucks off german star. It is also a pretty easy install as well. A new cap is 5 bucks. Both of which I will install if it stays at 100C. If it creeps up higher I'm definately taking it back and saying 'you replaced my radiator and coolant pump and were instructed to make sure the cooling system was in perfect order... FIX IT FOR FREE!' Let's hope it doesn't result in that.
 

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Hey regarding the aux fan, how can I test it if it works at all? can I just hook it up ...

Hey regarding the aux fan, how can I test it if it works at all? can I just hook it up to the battery? I think someone mentioned doing this, but I don't want to mess anything up just yet. I never seen the aux fan go on and I just replaced the resistor for it which was in such bad condition in almost didn't exist.
 
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