[jwmnbmw]

Hi BMW colleagues,

My front AC quit on me and im sure its the AC Blower Motor assembly. I want to check the resistance on the resistor attached to the blower motor to discard the issue being the resistor vs the motor itself.

What are the resistance readings in Ohms that I should be getting when I test the terminals 1 through 4 in the resistor itselft.

This way i know if the fault is in the resistor or actually the motor.

 

[Doug Huffman]

E70 does not speed control AC blower with a resistor bank. The blower motor is BLDC, PWM commanded to the Blower Output Stage N2. Schematic wiring diagram in a moment ...

https://www.newtis.info/tisv2/a/en/...ir-conditioning-functions/ihka-blower/c919gk0

https://www.newtis.info/tisv2/a/en/...ir-conditioning-functions/ihka-blower/25K67rA

 

[ArgentoCarNut]

Hi BMW colleagues,

My front AC quit on me and im sure its the AC Blower Motor assembly. I want to check the resistance on the resistor attached to the blower motor to discard the issue being the resistor vs the motor itself.

What are the resistance readings in Ohms that I should be getting when I test the terminals 1 through 4 in the resistor itselft.

This way i know if the fault is in the resistor or actually the motor.

FWIW - Changing motor is very straightforward, and the part is inexpensive. In my case I swapped over the resistor from the old one, as I had to replace mine due to the fan becoming noisy

Sent from my iPhone using Tapatalk

 

[n1das]

FWIW - Changing motor is very straightforward, and the part is inexpensive. In my case I swapped over the resistor from the old one, as I had to replace mine due to the fan becoming noisy

Sent from my iPhone using Tapatalk

There is no resistor. The motor is PWM controlled by an electronic module that people frequently call a resistor.
https://en.wikipedia.org/wiki/Pulse-width_modulation

I had to replace the front HVAC blower in my 2012 X5 35d in July last year at around 220k miles. It quit on me in the middle of a weekend road trip from Nashua NH to Belfast ME for the annual Maine Celtic Celebration festival. It was record setting blistering hot and humid on that weekend too, the hottest days of the year. The motor bearings were worn and the lubrication was used up and the motor was howling and running slow due to shaft orbit. The motor was slowed enough that there was next to no airflow from the vents and the control module kept shutting the motor off to protect it from overheating and protect the module. The motor would be off for a few minutes and then start up and howl again, only to shut down again a couple of minutes later. The 200 mile road trip home was done the HVAC system OFF and with all windows down while on the highway so that the ride was at least tolerable in the hot weather. It was my "4-70 A/C" - all 4 windows down @ 70 MPH.

The new blower assembly included a new module with it. Replacing the blower was straightforward but it required being a bit of a contortionist to install. A friend of mine liked to call it "Dashboard Olympics." The job was straightforward but NOT fun. The trick is to be able to get your head fully under there to be able to look straight up and see what you are doing. The information on NewTIS was a big help.

I haven't had to replace rear blower motor yet with the car only at 241k miles now.

 

[Doug Huffman]

Dashboard Olympics is why I do my cabin recirc air filters. The car is mine to keep as perfect as I can and not pay some jackleg to hurry through a horrible little job. (I***8217;m 71, 240#, arthritic, nearsighted, ...). My car!

It is unfortunate that the blower FSU module is not capable of self-diagnosis. I wonder if it is in later platforms.