Need some help from some of the guru's on here.

Original problem: setting 1-3 on MCC wouldn't work;

Resolution: I replaced the fan resistor and fan motor.
This

New Problem: setting 4 on my MCC doesn't work. ( Setting 4 turns the fan motor off as if it were on setting 0).

Here's what I know: I replaced the fan resistor, fan relay and fan motor. Not sure what else could cause issue with setting 4.

Any help with be much appreciated. T

Thanks in advance!

 

Hi and welcome to the site.

Did you replace the fan resistor with a new one or used one?

 

Thank you, The fan relay and blower resistor were used. I could test the thermal fuse with a voltmeter on the blower resistor and it is not blown compared to the old one. I do not have a workbench therefore I couldn't test the relay. I did check the front fuse panel to make sure the 30W fuse wasn't blown.

Edit: I followed this guide to install the new blower resistor.

http://volvospeed.com/vs_forum/topic...guide-850sv70/

 

Sounds like problem 1 was fixed by adding a functional blower resistor.

Problem 2 could be caused by:

1. blown fuse 11-5 (30A); this is different fuse that's used for speeds 1-3.
2. or bad A/C fan switch
3. or bad fan relay; the relay is only used on high (4 setting) speed.
4. or faulty wiring..

do you have a schematic? Time to get in there with a VOM and troubleshoot it..