28 replies to this topic

[ProStreetDriver]

So I'm trying to solve the problem with my 96 Volvo 850 Turbo... The blower motor stays on regardless if the key is on/off or what position the fan speed is in. The car does have dual climate control. I actually bought the car with this issue, so I'm trying to sort it out.

I have cleaned the ignition switch plug with contact cleaner and have unplugged it and there is still constant voltage at the blower motor plug. I've also disconnect the one temp sensor on the passenger side duct and also disconnected the control unit with the same results. I have pulled the blower unit plastic backer off... The brushes and armature is done, so the blower motor will need to be replaced. I've also scanned for codes and there isn't any.

If anyone could help me out, it would be greatly appreciated

[erikv11]

You mean only the blower motor, not the whole ECC unit? I am pretty sure this problem is due to the blower motor resistor gone bad. Can't really be of any more help though, wait for someone else to chime in ...

[T5BLACKattack]

Yes, blower motor resistor usually causes this problem!

[Tech]

The ECC unit gone bad can also cause the same issue.

[ProStreetDriver]

This is what I've unplugged from the system:
-power module
-passenger side temp sensor
-ignition switch
-damper control units
-some blue relay in front of the duct

Hopefully I'm somewhat isolating the issue to one source. If I unplug the ECC, will that most likely be the source to the issue then??? Also how do I remove the ECC???

[Tech]

The ECC just pulls out. Remove the radio and then reach in to behind the ECC unit and pull it out. But the dash can tear your arm up pretty good so use a rag or a towel on your arm. Also they can stick in there pretty good.

When you get it loose see if something it rattling or moving around in there. Alot of times the resistors or capasitors will fall off the circuit board.

[BEJinFBK]

Both ECC and MCC are dual climate control systems.
Just to make sure, ECC has an AUTO mode and fully variable fan speed.
The temp knobs for ECC are also marked in degrees, not colors.
If you have a 4 speed fan switch, your climate control is Manual.

On your car, the power for the blower doesn't go through the ignition switch.
It's connected to the battery 24/7. The ECC controls the ground to the blower.
It does that with the power stage ( that everyone calls a resistor ).

In the diagrams attached, it's called out as 4/31.
 96 850 ECC Diagrams.pdf   440.32K   43 downloads
 96 850 ECC Component Locations.pdf   388.76K   14 downloads

Yours is probably toasted, so it doesn't shut off.

It probably got fried because the blower is on it's way out.
Regreasing the bearings may help, but start shopping for
a powerstage AND a blower. You'll need it soon enough.

[ProStreetDriver]

Yep, the ECC does have the auto position for the fan speeds and it's marked in degrees. I can't get the ECC out because the wood grain is in the way. It's catching on the bottom corners of the ECC. I don't want to damage the wood grain and unfortunately it looks the be glued on. I tapped the ECC around to hear if anything is loose inside and I didn't hear anything rattling.

Even if I unplugged the power stage, the fan would still be on???

[(_8*(l)Homer]

ProStreetDriver - you can get it out, i almost broke a tooth when it came out at me. Pull the radio out, pull with all of your might to pop that ECC out. it won't damage the grain. There are clips that hold it inside the hole that you can't reach with human appendages.
So, just act like you have nothing to loose and pull that sucker out.

P.S. I had the same problem as you. Blower was on constantly, it was the in the ECC. I just replaced the ECC with one I had laying around.

[ProStreetDriver]

It's legimately catching on the wood grain lol... It'll come out and it moves, but it's making the crackes expand in the corners of my wood grain.

[BEJinFBK]

Sounds like you have aftermarket "stick-on" wood grain...Bummer.
Still very likely it's just the power stage, though.

[ProStreetDriver]

I would have posted earlier but I've been fairly busy the last couple days

So I took some images of the wood grain... If it's the aftermarket stuff, I'll just pull it off (assuming there is not fasteners in behind it) and then replace the stuff with new trim after. I just noticed that the stereo is also being affected by the wood grain too, but it has a little more wiggle room. I thought about heating the trim up with a heat gun so it would soften the glue and I could slide it down slightly. Maybe if I have time this weekend, I'll take a trip to the wrecking yard and see if they have any Volvo parts and pick up an ECC and power stage unit. If it's the power stage unit, I'll just end up buying a new one. I just don't want to lay out the money and find out it isn't the problem.

[Tech]

That is aftermarket stuff. You might be able to use a razor and trim some to make it easier to slide out.

[DVolvoguy850T5]

Hey ProStreet, That stuff may be held in by double back tape. Use a hair drier on hot and soften the adhesive and try a bone tool to pry it off. You may be able to re-use it if you can find some 3-M onion skin tape.

[ProStreetDriver]

Picked up an ECC for $20 Well that wasn't the problem, so I have a super cheap spare which is good... Teared the wood grain off and it was pretty bad so I threw it out. I'll replace it with new stuff hopefully.

So it's got to be the power stage unit then, right???

[erikv11]

Likely is, yes. They definitely fail more frequently than the ECC units.

[ProStreetDriver]

Bumping back on my old thread here... Just finished school, so now I finally have time to trouble shoot this thing over again. So I checked out it does have a fuse under the hood, pulled it, and there is still power going to the blower motor plug regardless if the power stage unit is attached or not.

I really hate buying a new part that costs me $150 and finding out it's not the problem. And I can't exactly find them used either.

I see someone has done something with the wiring too... The antenna fuse spot is now for the cigarette lighter(someone wrote on it with marker).

[BEJinFBK]

The fuse is #5. And unless you pull it, there is ALWAYS going to be power at your blower motor.
It feeds directly from constant battery power - That's just how Volvo designed this M/Y car.
( In later years, an ignition controlled relay was added ).

The power stage is on the negative side of the motor and regulates the ground, not the positive feed.

Go back up to my post here from June ( #7) and have a look at the diagram.
The motor is 6/28, Power stage is 4/31. Fuse is 11C/5.

Your power stage is probably toast. And more than likely because your blower motor has dry bearings
and is pulling too much juice. Replace that spendy power stage without dealing with the motor and
you'll kill it dead before very long.

[ProStreetDriver]

Still having the problems... Ordered my parts and just got it yesterday. Installed the new power stage unit and the new fan and it's still on with the key off.

Any ideas... Now I'm thinking it's a relay. What relays control the hvac system and where are they located???

[DVolvoguy850T5]

I am just throwing this out here and am not sure but do you think it could be the contact assembly on the back side of ignition switch? Just a thought now... Not sure.