s40 blower motor changing speed on its own

[andrew]

hi im new to the forum but was wondering if you can help me i ve got a s40 1.8 2003 with air con but no climate control the blower keeps changing its speed on its own ive discovered buy trial and error that it seems to be the switch if you just touch it without turning the knob the speed will change ive taken the unit apart but cant see any dry soldered joints or any other problem so just wondered if anyone has come across this fault and fixed it without buying a new unit as its very expensive from the dealers thanks for all your help

[Haizum74]

hi im new to the forum but was wondering if you can help me i ve got a s40 1.8 2003 with air con but no climate control the blower keeps changing its speed on its own ive discovered buy trial and error that it seems to be the switch if you just touch it without turning the knob the speed will change ive taken the unit apart but cant see any dry soldered joints or any other problem so just wondered if anyone has come across this fault and fixed it without buying a new unit as its very expensive from the dealers thanks for all your help

Hello and welcome to the forum.

Funnily enough yes, I have had this problem on both my T4's and its down to the solder joints. They may not look dry and cracked however just tonight I took these pics of what they look like very close up (if you have an android phone you can download an app called cozy magnifier)






and this is how they should be (this is the far right temp gauge part)



So, try and put some fresh solder on and give that a go. I actually got a second hand part for mine which sorted it (it did the slow/fast bit for a second then settled) but I am going to try and solder the old one and see what happens, apparently it has been done before and solved it. If not then it could also be the resistor but that usually shows symptoms of the blower only working on setting 6.

If that doesnt fix it then it could be the potentiometer that's jiggered too.

[M-R-P]

hell - if I can bodge-solder a DIM for a year, this should be a breeze mate

[CONDYBOY]

If not the solder joints there's a small unit behind the glove box that controls the fan speed. it looks like an oversized diode or a small battery and is silver in colour. had to replace one on my v40 a couple of years ago.

[Haizum74]

If not the solder joints there's a small unit behind the glove box that controls the fan speed. it looks like an oversized diode or a small battery and is silver in colour. had to replace one on my v40 a couple of years ago.

Thats if its only working on the highest setting. Reason being is that the resistor doesnt control setting 6 (effectively its off). If the blower is going fast and slow on one setting then its the solder joints or the variable resistor