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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| Radiator Aux Fan Help
Greets,
With temperatures on the rise, I have noticed the coolant temperature inching up to the 3/4 range, and sometimes getting close to the bottom of red with the A/C on.
Yesterday, I got out to have a look, and low-and behold, the Aux fan was not on!!
I bypassed the system, and hooked the fan up to 12V, and voila! the fan DOES work.
My question is:
I have scoured the wiring diagrams in the owners' manual, my EPC and the WIS and I can find zip about an AUX fan!! Is this an "extra" someone has added in the past?
As I recall from some post way gone by, someone had a manual switch to turn it on/off ad librium.
Is it a no-no to hook up a switch directly into a circut from the fuse area to the fan, or does there need to be a relay??
Thanx |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Radiator Aux Fan Help
G-AMG - 4/30/2007 8:57 PM
Greets,
With temperatures on the rise, I have noticed the coolant temperature inching up to the 3/4 range, and sometimes getting close to the bottom of red with the A/C on.
Yesterday, I got out to have a look, and low-and behold, the Aux fan was not on!!
I bypassed the system, and hooked the fan up to 12V, and voila! the fan DOES work.
My question is:
I have scoured the wiring diagrams in the owners' manual, my EPC and the WIS and I can find zip about an AUX fan!! Is this an "extra" someone has added in the past?
As I recall from some post way gone by, someone had a manual switch to turn it on/off ad librium.
Is it a no-no to hook up a switch directly into a circut from the fuse area to the fan, or does there need to be a relay??
Thanx
Which G? The 280GE? As I remember, the aux fan works on a temp sensor and it's part of the A/C circuit. I don't remember where the sensor is located; but methinks it's in or around the radiator. |
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DesertStar
Expert
Date registered: Apr 2006
Location: San Diego, CA USA
Vehicle(s): 85-280GE/95-G320/08-G500
Posts: 2156
| RE: Radiator Aux Fan Help
I have found the fan to come on when the needle actually gets in the red....which is usually on a hot day with a/c running and you are stopped, or pulling a grade. Unfortunately, it will get in red when I stop to get a sodapop at a store and only works with ignition switch in "ON" mode. I have pondered wiring to a switch versus leaving the switch "ON" (which I dont) but from what I have read on the forums 3/4 on the needle is somewhat normal for the M110. You can test wiring to your fan by grounding out the wire that is connected to the thermo switch on the head. This is for a W460 which I am assuming is the G in question.
I can verify wiring if you would like as I had same concerns last year and found all to be as it was suppose to.
The switch is one of the two sensors in top right of the photo...I cant remember which one as I am at work and cant verify till later.
Mike
Edited by DesertStar 4/30/2007 11:24 PM
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hus55
Expert
Date registered: Apr 2006
Location: north cyprus,lapta.
Vehicle(s): 300GDS, G300 LONG,300GDT CLK55 AMG CAB.
Posts: 2230
| RE: Radiator Aux Fan Help
shakir is the man for this topic.he has a brilliant set up on his m110 and will guide you in the right direction about switches and relays etc.
you may want to pm him for a quick response. |
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Ernest T Bass
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Radiator Aux Fan Help
On my old 300e the aux/ac fan failed a few times and it was the temp sensor in the refrigerant line near the ac compressor. In the end the solution suggestion of the Mercedes mechanic was to bypass the switch an let the fan run all the time – to change it means undoing the gas lines and re-gassing. It was no problem in Miami – had the ac on most of the time. I never had any other problems with it.
But even in the Miami heat the water was not getting noticeably hotter with the aux fan off it was just the ac that would not cool down with out it. I would check out the cooling system thoroughly as that where the problem could well be.
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Mark G
Date registered: Jul 2006
Location: Ft. Lauderdale, FL USA
Vehicle(s): 1985 280GE LWB AT
| RE: Radiator Aux Fan Help
A good place to start is the fuse box (if we are talking the 460). Actually behind the fuse box. There is where the power comes from via a relay to the fan. The relay is activated via a negative ground from the thermo sensor on the engine head. The power wire to the fan can get hot.
Many years ago I was trouble shooting the same problem and finally just dropped the fuse box down. There I discovered all sorts of issues. Mostly with crimped connections getting hot. It was obvious that previous owners and/or Federalizers had their hands in their so can not attribute some of the trouble I found to Mercedes workmanship.
For these older G’s I do suggest a general maintenance of dropping the fuse box for an inspection. You will obviously see problem or hot spots (if any). The fixes are normally as simple is re-crimping new connectors. But do it right with good crimping and heat shrink insulators (a dab of dielectric grease also). Poor crimping leads to resistance (heat) and future trouble.
By the way, for anybody with an electric aux fans not working. They can be opened up and serviced.
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| RE: Radiator Aux Fan Help
Thanx all for the input.
After sifting through the "Pasta Primavera" of wiring mess, I was able to backtrack the wire back to the relay.
In tracking down the various possible sources of fault, I will need to check out the relay. I'm sure this is a very basic question, but:
HOW DOES ONE "TEST" A RELAY?? to see if it is faulty.
Thanx again. It is such a treat to have a "brotherhood" of G-owners/lovers who are so willing to help one another out!!
Cheers! |
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| Re: Radiator Aux Fan Help
Mike, or anyone else, could you kindly identify- which of the two switches in the photo is the thermoswitch(s)? and by "grounding" the wire, is there only one wire, and I just ground it to the block?
Also, Steve at Eurotruck was very kind and sent me the wiring diagragm, and it actually shows TWO thermal switches sending to the Aux Fan Relay.
In Mike's photo, could BOTH the switches be the ones noted above?
Thanx in advance! |
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Phil
Veteran
Date registered: Jun 2006
Location: Newton, Massachusetts
Vehicle(s): 1984 280GE
Posts: 218
| Re: Radiator Aux Fan Help
Don't know how relevant or helpful this is, but, when faced with the same problem (cure was to fix a small, under-dash leak in A/C system) I considered doing something similar: bypassing to a 12v and running a toggle switch to the dashboard. This would allow the driver the discretion as to when the aux fan kicked in. |
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Ernest T Bass
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Radiator Aux Fan Help
Now I am very confused. The switch in Mikes photo looks like the thermo time switch for the cold start valve. Or is there a switch in the head to start the aux fan too? Isn’t the ac fan switch on or near the ac drier? It has two terminals 255 in the picture.
The solution I used was to short out the two terminals with a flat fuse if that starts the fan then I would have thought the relay was ok and it’s the switch that’s the problem.
Edited by Ernest T Bass 5/2/2007 11:53 AM
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fourbyfourclub
Extreme Veteran
Date registered: Apr 2006
Location: New Jersey, USA
Vehicle(s): 300G
Posts: 302
| RE: Radiator Aux Fan Help
Patrick, check your PM,
regards,
Vlad
fourbyfourclub |
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DesertStar
Expert
Date registered: Apr 2006
Location: San Diego, CA USA
Vehicle(s): 85-280GE/95-G320/08-G500
Posts: 2156
| RE: Radiator Aux Fan Help
Sorry for the delay. In the workshop manual under M110 section page 060/10 shows the detail that I have photo below. I did not post the best photo so here is more detail ...starting left to right in the photo,
Plug
Coolant gauge pickup sensor
Thermo time switch for cold start
Plug
100 degree temp switch and intermediate piece M18 x 1.5 for auxilliary fan air conditioning system.
The switch works in such a way that once temp is reached it completes the circuit. Right now I am having a senior moment and cant remember how I tested, but I do remember reading about how to in BWF I believe.
Here is another schematic...rather crude but has parts listing.
http://www.performanceproducts4benz.com/Drawings.aspx?bmid=148
I wish I knew how to save pages of EPC or Workshop Manual so I can share on occasion.
Mike
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sloughboy
Regular
Date registered: Jul 2006
Location: Edmonton, Alberta Canada
Vehicle(s): 1989 280 ge swb; 1997 G320 lwb; lexus gx;
Posts: 92
| RE: Radiator Aux Fan Help
While we are on the "too hot" topic, what is the correct operating temperature for the 110 engine, and how does one check out to see what the temperature actually is? I could then verify if the temp gauge is reading correctly. |
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| Re: Radiator Aux Fan Help
G-AMG - 5/2/2007 10:25 AM
Mike, or anyone else, could you kindly identify- which of the two switches in the photo is the thermoswitch(s)? and by "grounding" the wire, is there only one wire, and I just ground it to the block?
Also, Steve at Eurotruck was very kind and sent me the wiring diagragm, and it actually shows TWO thermal switches sending to the Aux Fan Relay.
In Mike's photo, could BOTH the switches be the ones noted above?
Thanx in advance! Symply grounding the wire must run the fan, if everithing else is OK. at least this works on the other cars, never tryed on my G. the thermostathic switch is the one with "100 C" stamped on the base. good luck. in the worst case you can run wires & toggle switch, dont forged relay  |
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| RE: Radiator Aux Fan Help
Mike, thanx a million for the extra pic/explanation.
I will trouble shoot this weekend.
To all who offered their expertise, I am indebted!
Greets |
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G-AMG
G-Class DIY Host
Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
| RE: Radiator Aux Fan Help
FOLLOW-UP:
Well, I tried grounding the coolant sensor, but no joy, it did not turn the Aux Fan on. Also, I noticed only 7,5 Volts at the sensor. Strange.
To make a long story short, I ended up just bypassing the whole "automatic" sequence, and just hooked up the Aux Fan to the Foglamp Switch, so now I have 100% control of the Fan. I would assume the Fuse for the Foglamps should be sufficient to handle the Aux Fan.
I really appreciate all your input and help.
Cheers. |
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