The fan is not working when I turn on air conditioning on 2003 BMW 325i

Air conditioning worked well the night before and then it stopped completely in the morning without any warning. The fan/blower did not come on but I could feel the air conditioning when I am driving. What went wrong? Please help.

Asked by for the 2003 BMW 325i
possibly fan speed resistor, if we remove the air con from the equation and substitute it with fan operation.

If you are talking about your cold air, fan operation normal, possible failed compressor or tx valve.
Thanks Journeyman! The air conditioning seems working but the fan is not at all. So what is a fan speed resistor? is it something that a mechanic will charge a lot of money to fix?