Question about 1995 Mercedes-Benz C-Class

2 Answers



Posted by on

  • Anonymous Mar 25, 2014

    The car overheats after operating for sometime with the AC on. Looked at the cooling fan operation and the fan never came on when the AC was turned off. Disconnected the temp sensor and jumped it and the cooling fan still did not come on. Looked at the fuses under the car hood and inside of the cabin in the drivers side and all appear okay. The cooling fan is electric which discarted a fan clutch assembly. I think that the problem is electric as it comes on when the AC is turned on. Again after sometine of the car operating with the AC on , the AC is drop off line and the car starts overheating.



2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Master
  • 6,784 Answers

Hi. here are a few steps that will help you troubleshoot this fan issue you are experiencing.

Step1 Check for broken wires or loose connectors around the fan circuit. Inspect connectors at the fan motor, relay, sensor or heat sensitive switch, and the Electronic Control Module (ECM)--your car’s computer control system. Also, make sure to check for a possible blown fan fuse. These are common and overlooked troublesome spots that may cause a fan to fail. Step2 Run and bring the engine to warm temperature. With the engine running, use a voltage test light to check for power to the motor fan. Be extra careful and make sure to keep your hands and tools away from the belt, fan or any other engine moving parts. If voltage is reaching the fan motor, the test light should glow. Step3 Turn off the engine after you see the light glow. Apply direct voltage to the fan motor from your car battery using a pair of spare wires. If the fan fails to operate, replace the fan motor. If the motor operates, your problem is in the motor connector. Step4 Locate the heat-sensitive switch or heating sensor if the fan motor operates with direct voltage and the test light did not glow. You should find the sensor in the radiator, engine block, or thermostat housing. Step5 Measure the resistance across the heating sensor with the multimeter. With the engine at cool temperature (engine off), it should register infinite resistance; with the engine at warm temperature (engine off), you should read low resistance. If both readings state infinite resistance install a new heating sensor, that’s the cause of your failing fan. Step6 Check the action of the fan relay if the heating sensor is registering variable resistance. Your service manual should specify the power and ground wires according to color codes and the proper way to test it. If the fan relay fails the test replace it with a new one. Step7 Check the connections going to the ECM after you determine the fan relay is working properly. If you find broken wires or loose connectors, make the necessary repairs. If you suspect a defective ECM take your vehicle to a service shop for a computer analysis. In most cases, the ECM is rare to be the cause of a failing fan. The above steps should take you to the root cause of your problem and help you fix the cooler fan.

Please rate and god bless.

Posted on Mar 25, 2009

  • Michael Masters
    Michael Masters Mar 25, 2009


    • Most
      automotive service manuals will show the wiring diagrams for the
      different electrical and electronic system components. Having the
      service manual for your car handy to locate components and look up
      specifications will make your troubleshooting task much easier.

    • A
      service manual can be purchased at most auto part stores. Also, most
      public libraries maintain an updated section of automotive service
      manuals that you can consult free of charge.

    • Keep
      your hands away from the fan, belts, or any other moving parts while
      working on your engine, they can easily catch and rip through your
      fingers, hands and arms.

    • Always
      wear short sleeve shirts and avoid wearing jewelry or watches while
      working on your car engine, especially while the engine is running.
      Clothes and jewelry can get trapped in moving engine parts and cause
      severe injury.


  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.


    An expert that has over 500 points.

  • Expert
  • 408 Answers

Hello,good day,you mention all the possible cause,your aux. fan relay should also check,in your fuse box,remove the plastic cover,check relay for fan mark with letter d (1st stage) and c (2nd stage)then try to remove the connection of your fan,check if connector 1 (white and black) have power,connector 2 (brown) should have ground connection, if not check your relay,i'm looking the wiring diagram,it's only the relay or fuse is defective,ty

Posted on May 31, 2009


1 Suggested Answer


6ya staff

  • 2 Answers


Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a 2000 Oldsmobile alero, it’s has new head gaskets, intake gaskets, new thermostat and coolant temp sensor but my coolant fans won’t turn on, if I turn the ac on they still don’t turn on, but if I...

What does scan data show ? Is the PCM - engine computer seeing coolant temp sensor input data ? Can the fans be truned on bi-directionally ? Do you know what that is ? Factory tech 2 scan tool can do that .
Your vehicle has two cooling fans and three relay's that the PCM energizes to control fan speed . Did you take your vehicle to a qualified repair shop ?
Relay Driven Dual Cooling Fan Diagnostics

Free wiring diagrams here

Sep 21, 2018 | Oldsmobile Cars & Trucks

2 Answers

Cooling fans run with ac on but not with ac off help

What make , model an year vehicle ? Is the engine over heating ?

Feb 26, 2017 | AC Cars & Trucks

2 Answers

Shouldn't the radiator fans kick on when ac is turned on?

it depends on the kind of wiring system....but most cars ...the fan wil always start anytime the AC is switch ON.... and some cars the fan works with the thermostart

Oct 15, 2015 | AC Cars & Trucks

2 Answers

Heats up when is in traffic or idling

Fan/fans may not be coming on. See if the fan (if only one) kicks on when you turn the AC on. If it has 2 fans see if one of them comes on when the AC is turned on.

Jun 26, 2015 | 2005 Chrysler Town & Country

1 Answer

97 accord lx overheats unless ac is on

If the cooling fans are not coming on when the vehicle is overheating try this.

Look for the coolant temp switch B. it will be located near the thermostat housing on the back side of the passenger side of the engine (follow the lower hose to the engine). It will have a white with green wire and a black wire. Unplug it, turn the key to the run position, the engine does not need to be running. ground the white with green wire. if the fans come on replace the coolant temp switch B sensor.

I’m happy to assist further over the phone at

Sep 18, 2012 | 1997 Honda Accord

1 Answer

95 eagle vision 3.5l......cooling fans in-op.

There are actually two relays. You may be looking at the second one. The first one turn is turned on by the pcm based on temp sensor inputs. The other is the high speed relay turned on by the ac switch. Do the fans come on when you turn the ac on? I would pull out the low speed relay and probe the relay socket with a volt/ohmmeter. Make sure the pcm is sending a ground signal to the relay when the engine reaches operating temp.

0900c1528006ae42 (1)-gepcz2zwodkuqhqcnry40435-4-0.gif

Not sure about the failure rate of the parts, but a relay is easy to test.

Aug 01, 2017 | 1997 Eagle Vision

1 Answer

I turned my ac in an took a 30 mile trip n back. My vehicle started overheating n now it keeps overheating. Wat could be wrong with it?

Sounds like the electric cooling fans are not engaging. There is a sensor that is usually found on the side tank of the vehicle that senses coolant temperature. When this sensor goes bad it does not start the electric cooling fans and then the vehicle overheats from the extra heat produced from the AC system and increased engine load. It is not the thermostat or it would overheat quickly upon startup in about 10 minutes. Check the electric fans. Should be two of them.

Apr 24, 2012 | 1993 Jeep Grand Cherokee

2 Answers

2004 pacifica radiator overheats every couple

A fan is on or off not slow do any fans in your house run slow because they are old?Your thermostat fan or temp sensor is bad

Jun 27, 2010 | 2004 Chrysler Pacifica

2 Answers

Both radiator cooling fans won't turn on vehicle overheats

The fans come on only when hot or the AC is on. There are many fuses that have to be good for it to work. The fan relay should have 2 pins hot with the key on, The other 2 should be ground. with the key off one should be hot and the other can then be ground the other pins that are ground one of them is the fan. the other becomes ground when the computer turns the fans on. If you don't have a pin thats hot at the relay all the time then theres a blown fuse or even the power wire from the battery at the battery

Nov 02, 2009 | 1994 Buick Roadmaster

1 Answer

2000 Intrepid with no AC and overheats. Neither radiator fan comes on when AC is turned on. Possible fan relay?

Very possible - also check that the fans actually turn by hand (ignition off of course) as sometimes the fan motors seize up and blow a fuse. If you have access to a scan tool and the fans are not seized, you can actuate the relays manuallly to see what works and what doesn't.

Jul 04, 2009 | 2000 Dodge Intrepid

Not finding what you are looking for?
1995 Mercedes-Benz C-Class Logo

1,713 people viewed this question

Ask a Question

Usually answered in minutes!

Top Mercedes-Benz Experts

Colin Stickland
Colin Stickland

Level 3 Expert

22485 Answers


Level 3 Expert

85216 Answers

Jonah Oneal

Level 3 Expert

14092 Answers

Are you a Mercedes-Benz Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides