Cooling fan starts running when started from cold and climate control system is dead

[Sean Ng]

Hi Guys

I need your help!

My MB is 1996 E230 estate W210 series of 140k mileage with auto transmission and air conditioner. Recently the climate control system appears to be dead. No air - cool or hot - comes and all switches on the instrument cluster do not work at all. My first response to that is something about the fuses. But all the fuses are OK!

However, I have also noticed the followings:
(1) The cooling fan starts soon after the engine is started from cold, and the cooling fan then never stops until I switch the ignition off! That is very abnormal since the cooling fan should only run when the engine temperature is very hot - not when the engine is cold.
(2) The temperature gauge shows no overheating. The engine keeps at 80 degree centigrade - the normal operational temperature for engine (I have done a road test for 10 miles in 15 minutes).

What I think the possible causes of the problem could be:
(A) A faulty sensor (but do not know which one) sends a wrong message to the electronic control unit that shuts down the climate control system, including the air conditioner, and instructs the cooling fan to be on all the time!
(B) The electric cooling fan control unit (located under left-hand front wheel arch according to Hayes manual) is faulty.

Below are the conditions of my car relevant to the situation:
(a) The coolant level and condition are normal (renewed 3 months ago).
(b) Not a single warning sign flashes on the dash board.
(c) The air conditioning sensor located in the thermostat housing area appears OK.
(d) The condition of the auxiliary belt is good.

I have stopped using the car to avoid engine overheating. I wonder if somebody can point me out the problem and advise me what to do if I intend to repair it in a DIY manner. For any further information you may need, please shout.

Looking forward to seeing your shared experience and advise.

Regards
Sean

 

[pascal]

Not sure whether you paticular car has an OVP relay (was on the previous 230).

It would be behind the battery, and would have a fuse on the top of it.

Pascal

 

[Lordjellybelly]

AIR CON 240 C class 1998

Funny you should say that.....the air con on my recently aquired 98 c240 ceased abruptly a couple of days ago. Let me be more precise; although dials set there was no fan assist at start up although there was ice cold air through the vents when at 20mph + but no fan. Fuses were OK. A day later all was normal. I`m not an oily rag person and comments would be helpful. :lol:

I`ve also got an intermittant bulb blown warning light but all bulbs are OK.

 

[Sean Ng]

Not sure whether you paticular car has an OVP relay (was on the previous 230).

It would be behind the battery, and would have a fuse on the top of it.

Pascal

Hi Pascal

Do you mean Over-voltage protetion relay? If not, please tell me more about what OVP relay mean. I have found a mounted black box under the bonnet on the left-hand (passenger side) rear corner. I am going to open it and check the fuses.

Regards
Sean

 

[Sean Ng]

Hi Pascal

Do you mean Over-voltage protetion relay? If not, please tell me more about what OVP relay mean. I have found a mounted black box under the bonnet on the left-hand (passenger side) rear corner. I am going to open it and check the fuses.

Regards
Sean

Hi Pascal

I have checked the fuses in the mounted black box. All 3 of them are OK. I wonder what other area I should check.

Awaiting for advises.

Regards
Sean

 

[Sean Ng]

Hi Guys

The problems of my MB are fixed! Just want to share the experience so that in case of the same problem you can fix it yourself quickly and saves plenty of money in repair.

After lots of research over many technical websites, technical forums and Haynes manual, I considered the fan and its related sensors should be functioning OK. It should be some kind of connection that caused the whole issues. As the only thing that I had not done was the Heater Control Panel (above the radio), I decided to shed some light on it. By removing and then refitting it, the air conditioner and the fan work magically back again. My conclusion is that the problems lie on the 2 LOOSE opearting rods at the back of the Heater Control Panel.

Hope this leaves you a good reference.

Regards
Sean