so my climate fan on my 850 from 94 is not really working. when i have the slider on manuel it sometimes spins but slowly and sometimes it works fine. but when i have it on auto nothing happens...
i tried reading the fault codes and this is the madness i got:
122 Outside temperature sensor open circuit or shorted to 12 volts
324 Floor/defrost damper motor active too long
411 Blower fan seized or drawing excessive current
414 Driver’s side interior temperature sensor inlet fan seized
417 Passenger’s side interior temperature inlet fan seized
418 No control signal to blower fan power stage
420 ECU fault in program memory

what could be wrong? what do i need to replace?

 

a couple common points of failure on the 850s are the ballast resistor and the blower motor itself. As I recall, the resistor is only in play for the lower speeds and is bypassed when on full so if your low speeds don't work but top speed does - check the resistor. For the blower motor, they can get noisy, draw too much current or fail entirely. The fact that when in manual mode it doesn't seem to spin freely or varies its speed w/o following the manual controls, I'd say the blower motor needs to be replaced. I'm thinking the ECU is sensing the current draw and shutting off the power.

Check out volvotips.com for a suggested diagnostics process. You may want to clear the codes and see what resets - they may have been there from a prior voltage event or may be related to a badly behaving fan motor messing with current/voltage levels.

 

i tried replacing the ballast resistor, fan and ecc and now all controls work except for the fan still and im still getting:
417 Passenger’s side interior temperature inlet fan seized
and
418 No control signal to blower fan power stage

what more could be wrong?

 

I think the 417 code is for the fan opening that is under the passenger grab handle above the door.