1993 Volvo 850 ECU failure

monkeyy337 · Post by **monkeyy337** » 06 Jan 2010, 14:54

I have replaced the heat/AC ECU panel three times in the last 6 months due to the fan speed switch not working. When ever the switch quits working the 2 system failure lights start blinking so in goes another ECU panel. Funny thing is the third time (failure), the fan speed switch starting working again after a few days and the lights no longer starting blinking again. This is the first time this has happened so I don't really know where I stand this time. A retired Volvo mechanic told me to change both the blower motor and the blower motor resistor to be safe and even though they are not cheap $65.00 (blower motor) and $145.00 (resistor) I don't mind doing so if that is the real problem. I just don't want to spend the money and that not fix the problem. Using the vehicle on board fault diagnosis system the last time (system failure) the following fault codes were blinked.
211
323
411
414
417
418
My question is what fault code causes another fault code to appear and if you were I would you just change the blower motor and resistor and see what happens from there? Thanks for any help from anyone who responds.

Post by **Ozark Lee** » 06 Jan 2010, 18:23

You have many codes but since this is a replacement controller it has actually remembered the fault codes from the previous vehicle it was in as well as any that may be relevant in your car.

My suggestion is that you clear the codes and then see which ones come back.

...Lee

monkeyy337 · Post by **monkeyy337** » 06 Jan 2010, 19:26

Its almost to late to clear the codes again and see what codes come back as I've got the system somewhat taken apart now. Guess I will just order a new blower motor and resistor and go from there. Thanks for your reply though.