2000 v70 Blower Motor/Resistor Question

[nwhitney]

Have you had the ECC codes read? A standard OBD II won't do, you need the fancy Volvo computer to read and clear these codes. Maybe instead of shooting in the dark get the codes read.

[Warren561]

Okay, pulled the motor, and got a surprise - a plastic bag had gotten into the motor and was all wound around the spindle. Unfortunately, even after removing all the plastic and resetting the codes (via battery disconnect), still nothing. Going to keep after it, it's COLD here.

When the fan rotation is blocked by something (in this case a plastic bag), and power is still applied, you the current will go sky-high and the motor (in particular the windings) and/or resistor will burn out.

Check the motor itself: Get some wires (alligator clips work best). Hook the negative side of the car battery (or other 12 V source) to the fan. Hook the positive side to the fan, then touch it (briefly) to the battery's positive side. If the motor spins, chances are the motor is still good (replace the resistor). The motor is a DC brush motor. Don't worry about mixing up the polarity, if will spin either backwards or forwards.

If the motor doesn't spin, then the motor is probably bad.

Most motors die due to wear and tear (ie the brush gets worn down). In this case, the motor will be intermittent. A jolt or some kind will usually push (what remains) of the brush into place and the motor will spin for awhile, until the brushes are worn down again. Based on your description of putting the old motor back in, this sounds like the case for your old motor.

For the "new" motor that got wrapped in the plastic bag, if it doesn't spin when battery power is directly applied to it, it's most likely burnt up and needs to be replaced. Replace that first before replacing the resistor.

Hope this helps.

[geoffmorrow]

Well here's the latest: Got a working motor and resistor in there, and changed the no. 31 fuse, and what happens, now that I have power to the motor, it comes on for about 1 second - just a quick puff - then shuts off. I even tried my spare ECC, and same thing. Since the generic scanner won't read the codes for this, I'm looking for someone who has, or has access to the Volvo scanner. Meanwhile, any ideas are greatly appreciated. Thanks to all for the great suggestions so far.

[BEJinFbk]

did you check the temp sensor? blow it out with compressed air? btw my blower and resistor went out together,

It's behind a small grill just to the right of the moonroof, defrost and INFO switches.
A quick shot may get the accumulated gunk of off the sensor and calm the ECC.

[j3sse]

Since I had a similar problem (motor did not turn at all), I pulled the motor out and connected it directly to the battery... no response from it. Since the motor only has two contacts, I'm assuming I've connected it correctly and the motor is indeed dead. I just wanted to make sure others agreed before I ordered a replacement. It seems like there's very little to screw up with this test though.

[Fish stick88]

If the blower can run off the battery why would there be a resistor, rather than a line in between the switch and power supply?

[BEJinFbk]

for the record, you might be overcharging you blower, the resistor is there for a reason. probably fried the motor if it wasnt done already.. thats like pluging a lamp into a oven outlet, (aside from physically not being able to

The blower is designed to operate at full voltage. The reason there's a resistor (MCC) or power stage (ECC)
is to provide a method of reducing the blower speed, not protect the motor from "overcharging".

No disrepect, but you are seriously off base with this reply. What you suggest is simply not possible.
"Overcharging", as you put it, could only occur with a car providing far more than 12 volts.
Any load ( like a motor or lamp ) will only draw the current it requires from a power source.
And there's no reason you couldn't plug a lamp into an oven receptacle - As Long As It's a 240 vac Lamp.

[j3sse]

So then, am I correct in assuming that I DID do it right and at the very least, my motor is fried and needs replacement?

[BEJinFbk]

Sure sounds like it. If you put known good 12 volts to the motor and it didn't run, it's probably toast.

[BEJinFbk]

If the blower can run off the battery why would there be a resistor, rather than a line in between the switch and power supply?

Again - The reason there's a resistor (MCC) or power stage (ECC)
is to provide a method of reducing the blower speed,
not protect the motor from "overcharging".

Short answer - To provide the driver with options for fan speed.