Blower regulator for E200

[bobmerc]

My E200 had an intermittent problem with the heater fan. It sometimes operated with the switch in the off position and one "click" clockwise, that is before the first fan speed, at the same time the EC light came on. At other times, the fan worked perfectly according to the speed set. The garage replaced the blower regulator, which didn't improve matters and I have now had to have the heater control panel replaced, at enormous cost! This seems to have corrected the fault. My question is, is it possible for a blower regulator to have an intermittent fault as I suspect it was replaced on a "trial and error" basis. I believe I read somewhere that the blower regulator either works or it doesn't. I would very much appreciate a knowledgeable reply before querying the replacement with the dealership. Thank you in advance, anyone that can spare the time. Bob M.

:-?

 

[jberks]

hi,
I'd tend to agree with you. The regulator in my experience makes the fan speed up and slow down on its own, and whistles a bit. It doesn't affect the EC light and generally doesn't switch the fan on with the switch off - though I guess it is possible.
To me, the EC light was the giveaway and reading your post I was intending to reply that I didn't think it was the reg and suspected the control panel.

 

[bobmerc]

Thanks jberks for taking the trouble to reply. I thought it unusual that both the regulator and the control panel should be faulty. I have rather lost my faith in this Mercedes-Benz dealership!

 

[television]

I think that this is the first fault of this kind that we have had

 

[bobmerc]

Trust me Malcolm, to have the honour of being the first with this fault - story of my life! You are a very knowledgeable chap, have you ever heard of the blower regulator having an intermittent fault or am I correct in thinking it either works or it doesn't? Also, can you confirm the regulator has nothing to do with the operation of the EC light? Sorry to trouble you, but I am trying to establish the facts so that I stand on firm ground before taking the matter up with the dealership. Bob M

 

[television]

I wrote all this out the other day and the reg pack as against the earlier resistor packs are 2 output transistors wired as a darlington pair, and this is a cheap way of doubling the output from a power transistor. I must have changed more than 100,000 in my working life and I keep some 3000 in stock. If water got into the ari intake box then this could damage the reg pac, but only to the point where is would behave the same way every time the fan was used.

There is no connection what so ever between the 2, the EC control purely turns off the air con and is not interested or connected in any way to the fan

 

[bobmerc]

Many thanks for your time and trouble Malcolm, everything is now much clearer. I am sure the dealership replaced the blower unit on a trial and error basis as the fault reoccured on the way home from the garage! Although I returned the car soon after, the mechanics said they couldn't find a fault and as it was intermittent I couldn't argue with them. Thanks once again. Bob M