1993 850 dampers inactive

mwiles · Post by **mwiles** » 20 Dec 2013, 13:09

After doing much research on the forums here, I'm still unsure of what exactly is going on with ECC (auto), so here it is.

Not too long ago, I noticed that I wasn't getting heat through the floor vents when the floor was selected on my ECC. However, when I switched it to Auto, the floor vents would open like they should (they also functioned properly in other settings too, just not the floor selection). Not too long after, they got stuck in defrost mode and now my position selector does nothing. The same night this happened, the fan stopped working too.

After 2 days, the fan started working again, but still no damper control. I pulled the floor/defrost damper out to clean the grease off the contacts, and I still get nothing. The 9v battery test does nothing as well.

My Volvo specialist here in town is confident that I need to replace the ECC control unit. This makes sense to me because the fan worked one day and came back on the next, but I'm also concerned that my damper motors may have issues too. I'm really not sure what to do next.

Thanks for any help in advance!

Post by **jblackburn** » 20 Dec 2013, 13:31

I would be inclined to agree with your mechanic. The early ECC units were known for intermittent to total failure with age.

The fan failure and damper failure only in certain positions on the knob would point to that as well.

The 9V battery test you refer to - was that straight to the motor?

Post by **rspi** » 20 Dec 2013, 18:21

Have you read the codes from the unit under the hood?