Climate control fan problem 1997 W140

[aceface]

Hi
When i switch on the fan on, the air coming out of the air vents is very weak.
After removing filter and checking it, it seems to run at the same speed, slower than it should, and there is no difference in the speed of the fan when turned up to MAX.
Anyone any ideas on where the problem lies?
Dave

 

[guydewdney]

almost definately the regulator pack - easy to get to and 15 quid iirc - open bonnet, remove large plastic shroud over fan (the long one across the car - 5 or so long phillips screws) - see fan - small pack on that.

 

[aceface]

many thanks

 

[gorse]

Heater Regulator

Hi

I have the same problem on my S600 Coupe, Took it to Mercedes last week where they did a diagnostic check and found the fan to be OK. They said the problem could be the heater blower regulator. Which they quoted approx £130.00 for the necessary part, I was reluctant to instruct them to replace the regulator as they were not 100% sure. How can I check that the regulator is working, what does the part look like and were you serious about the cost of £15.00 quid??

Brian

 

[jberks]

I put a reg on my W210 - From memory, around £125 for the part from MB and took me 30 mins to fit. Its under the passenger footwell on the 210 - cant comment on the 140.
Not seen one for £15 though!

 

[gorse]

Heater Regulator

Thanks ?jberks? for your reply, I removed the covers etc to expose the fan but did not see anything that looked like a regulator. So on reaching that point I decided to remove the fan and give it a physical check over. As far as I could see the bushes seemed ok, however the spin of the motor appeared a little tight when turned by hand, which make me think the bearings could be at fault. Before replacing the motor I applied a little oil to both bearings and it certainly worked better when it was all back together, albeit still slow and without real power. What does the regulator look like?
My questions now are
1/ can the bearings be replaced
2/ are overhaul kit available for these motors
3/ is this motor special to this model
Any help will be very much appreciated

Regards

 

[jberks]

I suspect it will be the regulator pack. Basically, the fan control sends a voltage between to the regulator and it changes the current to the fan accordingly, so its the regulator that directly controls the speed, not the switch. I suspect this allows Merc to use the same fan assembly whether climate is fitted or not.
I can only describe the 210 so it may require translation to yours but, if you remove the panel under the dash in the passenger footwell and look up at the back, there is a large plastic panel. Going into that is a rectangular plug with 3 wires attached, plugged up through the panel into the regulator. When I tested mine, I found one to be live, another earth and the 3rd changed voltage in accordance with the fan switch position - say 0 -7 volts. (You could test this to ensure the control is working ok) Remove the plug, the screws and finally the panel and the regulator is a triangular metal block with cooling fins on it and 2 spade connectors with wires going up to the fan. I replaced mine as it was whistling exactly like a fan bearing would - I didn't believe it was the regulator at first, but then the speed of the fan started to go up and down on its own so I settled on the regulator. A couple of screws and swap over the spade connectors, put it all together and job done. Doddle.

One note of caution - I was advised that if there was a problem with the fan - e.g. a blocked pollen filter, this could burn out the regulator over time, so if the fan is dodgy, you may be in for both.

 

[gorse]

Thanks, I will let you know how I get on over the weekend.

Best regards

 

[gorse]

Thanks for all your help, I received the necessary part to day and in 10 minutes the fan blower was working.