Intermittent Heater/Blower Fan

[daveenty]

CLK320 (2001)

When switching the fan between 1 & 5 there is no noticeable difference in noise (if any)
Then every so often the fan will surge in for a few moments and go off again.
This is with either the air con on or off.
I've been browsing this forum, and it seems that the problem could be a regulator?
The air con works fine when the fan is operating, unfortunately it just isn't long enough to feel the benefits.
As this car is still under warranty, I feel like taking it back, but need to know exactly what the problem is, so I can explain to my less than helpfull sales person, who suggested that it is normal behaviour.
My last one (1997 E320) wasn't like this.
All advice gratefully received

 

[vinay.chapaneri]

air con

hi
do have an AUTO button cos you said you had air con, as sometimes if that button is pressed and the outside tem is high and the temp setting in the car is low there will be fluctuations in fan speed

 

[daveenty]

No, no Auto button. Just the EC button to switch between Air con & heating.

 

[jberks]

The fan will run at whatever setting the switch is on. If it doesn't, 99/100 times its the regulator.

 

[daveenty]

This was the assumption I came to whilst browsing round this forum.
I'll take it back this week and persuade them that they need to repair/replace it.
Thanks

 

[jberks]

Just so you're aware, the reg is a sealed unit. Its a 10 min job to swap out but it can't be repaired.

 

[feathdt]

The regulator sounds like it could be the source of my problem as well then. I can switch the fan on and nothing happens but then after about 2 or 3 minutes it works fine AC on or otherwise. It can then work ok for a period or sometimes switches itself off for very short periods.

I only have AC NOT climate and it's only the fan not the AC itself which is fine when the fan works

2001 W210 320 CDI Estate

 

[jberks]

Could well be, though it's not unheard of for the fan to fail. The reg is by far the most common failure point though.
You can test it by checking the input and output voltages on a multimeter.

 

[geoffrey9492]

could you please be more detailed on checking input and out put with multimeter
3 pin connector in live and neutral out

 

[jberks]

I don't have exact figures but when I tested mine what I found was one wire 12v+ve, one -ve and the remaining (middle I think) was the control voltage. On mine it varied from something like 0v to 7v depending on what the switch was set to, so with the switch on 5, the wire was 7v, on 2 it was 3v etc. Baiscally if the switch is working properly, you should see a change in the voltage to the middle pin. I didn't check the output from the reg, but I imagine its a similar story.

 

[Aletank]

Just out of interest and for others, what does a regulator cost ?

 

[jberks]

Can't remember exactly but I think I paid around £125 for mine. I do remember whincing when they quoted me but they aren't repairable and I couldn't find any non franchised suppliers so bit the bullet!

 

[Wezzel]

This may sound silly but have you tried wiggling the blower switch. Mine fan was intermittant but when I prodded or wiggled the rotary switch the fan would go on and off.

I ended up taking out the switch assembly and giving it a good dosing with contact cleaner. It has now been fine for 18 months.

It is also a good thing to twist it back and forth (with the ignition turned off) several times now and again to keep the contacts from sticking. I think the trouble is that for most of the year the fan is left on number one and the contacts become corroded.

 

[jberks]

Doesn't sound silly at all. Certainly worth a go.