Heater blower with a mind of it`s own

[Mike2513]

My heater blower on my 98 E300TD w210 seems to have a mind of it`s own, it sometimes starts to blow low speed when it`s turnned off. Other times when heater is turnned off blower isn`t running but A/C compressor is still engadge.Can anyone surgest where to start fault finding? Used to be in the garage trade back in mid 80`s.

 

[Stevie A]

There are regulators that control the blower and these go wrong. Otherwise a loose connection but probably regulator. Someone else will know where they are on your car. Try a forum search for more clues as this is a fairly common fault.

 

[Mike2513]

Thanks Stevie i`ll have a look at the regulator and do some tests next weekend.

 

[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.