2001 BMW 330 Overheating

RAV573

MEMBER
2001 BMW 330
6 CYL
2WD
MANUAL
19,000 MILES

I recently overheated in me BMW 330ci, no pipe leak, I changed thermostat and waterpump. When I run engine its seems fine, but shouldn't the cooling fan kick in if you leave engine running for about 15minutes and turn on AC and heaters.
I need to know whether it is the fan or fan switch, my friend directly linked a battery charger to the Fan with a some wire r but the fan did not kick in?

1 Reply

DOCHAGERTY

MECHANIC
9,601 POSTS

Good diagnostic work. Although the auxiliary fan will not be commanded on with the addition of power alone, there are three wires going to the fan, two are for power and the other is a logic wire for bus communication. I would guess there is a problem with the fan, as you have done, but there are two things to deal with here, one is if the fan is inoperative and you purchase a replacement unit and it does the same thing then it leads us to the second thing which could be no logic from the A/C controller to command the fan on. This function can be requested with the factory proprietary software diagnostic unit called the GT-1 and the fan can be commanded on for diagnostic purposes. As a BMW technician, I would start with finding out if the fan is being requested on and if it is and is not coming on, then that should lead me to condemn the fan. The fan and it's controller called the final stage are one complete unit and cannot be purchased separately.