850 heater issues

volvomoose · Post by **volvomoose** » 15 Jan 2012, 14:22

Hey all...
I think I have exhausted all solutions posted before posting this. FYI

Driving my 1994 850 wagon last week I noticed that suddenly the blower stopped. I pulled over, tried all blower options on the ACC unit, but couldn't get it restarted until I turned the car off, waited a minute and restarted the car. The blower began again as it usually does. About two minutes down the road it quit again.

I got an used ACC unit and replaced it. It worked for about an hour of driving time and then the same issue; the blower just stops until i restart the engine.

I have also checked both units for signs inside of blown circuitry/resistors. Both units look fine.
and both fuses 5 and 31 both look good. I replaced them just in case.

What should i do next? Thanks ahead for the help!

Post by **BEJinFbk** » 15 Jan 2012, 14:53

When was the blower motor last replaced?
And do you have ECC or MCC? (What's ACC?)

Post by **rspi** » 15 Jan 2012, 15:56

It's likely a problem with the fan resistor. Search for those issues on the forum or google.

Post by **BEJinFbk** » 15 Jan 2012, 17:54

Keep in mind that it's bad motors that kill the resistors (in an MCC) or power stages (in an ECC),
not the other way around. When the motors go bad, they start pulling too much current, stressing
the speed controller. Resistors burn out altogether and power stages either die full on or totally off.
The motor should always be looked at and verified good before it's controller is considered.

It's also worth checking all the connections at both devices. Many owners have discovered overheating
connectors at both ends of the wire from the controller to the motor. That'll kill controllers, too.

speedbump · Post by **speedbump** » 15 Jan 2012, 21:49

I still have the original blower in my 93 850. I had to change the ECC because a capacitor died. They placed the capacitors right next to the motor controllers. There are 5 motor controllers and 5 capacitors. The #3 cap. died because it got the hottest and there's poor circulation in there. Volvomoose's blower may still be good. I was leaning toward fan resistor.

Post by **burnout8488** » 16 Jan 2012, 00:09

BEJinFbk wrote:When was the blower motor last replaced?
And do you have ECC or MCC? (What's ACC?)

Gotta be Automatic!

volvomoose · Post by **volvomoose** » 16 Jan 2012, 07:21

BEJinFbk wrote:When was the blower motor last replaced?
And do you have ECC or MCC? (What's ACC?)

I have the ECC.. sorry not the ACC. I don't think the blower motor has ever been replaced - I will have to check the blower motor and the resistor. I will search for a posting on both of those - I assume there is since this is the best forum in the world!
Thanks all!
Chris