turning up blower motor blows 5 amp fuse

[enf1945]

heat isnt on .

Blower motor OK

is it the climate control unit ?
something connected to it ?

could the water valves do this even if the heat isnt on ?

[NeedForBoost]

Not sue if it helps or even applies to your model but I just replaced my blower motor on my 08 335 and it has a 30 amp fuse. 5 amps seems supe low. One thing to remember about a DC motor is that when they aren't turning (as in start up) their load is very high, practically an open short if you will. So they spike the amps until they are turning and drawing much much less amp load. I'm no electrician but my brother is pretty good with electrons and he told me that years ago...

[enf1945]

No , the fuse that blows is a 5 Amp. The blower motor is a 30 amp like you said and that is fine.

This 5 amper. feeds both the CCU and the heater control Valve ( which are two solenoids ).

but i put the heater on and the fuse didnt blow.

[Eric93se]

There were other threads recently but I don't remember what the conclusion was, but the solenoids in the heater control can go bad, I think the problem was else where like a bad wire.

[gc325is]

Your problem may not be the blower motor being on, it just happens to be the last straw to cause the fuse to blow. Ex The fan causes a 1 amp increase but something else already draws 4 amps.

Some one would need to compare the increase in current when the "Blower" is on vs your car (however you should turn everything else off on that circuit). Sounds like you have a digital temp control car. Yes the control valves have power too them. Yes a stalled or stow motor will draw a lot more current until it is at speed.

[enf1945]

somehow turning up the blower triggered the heater control valve signal from the climate control unit. Then the fuse blew. Noone has a logic table of the CCU. WHo knows all the stuff that goes on.
I disconnected the heater valve connector and no more blown fuses and the car starts. CCU and OBC work.

Bad thing i notice is u cant get cold AC air to the windshield defroster now.
Bad because sometimes hot air wont clear the foggy windshield.

[johnf]

somehow turning up the blower triggered the heater control valve signal from the climate control unit. Then the fuse blew. Noone has a logic table of the CCU. WHo knows all the stuff that goes on.
I disconnected the heater valve connector and no more blown fuses....

If that was Fuse 31, check the resistances of both coils of the heater control valve. A fellow reported similar symptoms a few months ago and found one side was much too low.

EDIT: I found the thread.