1999 + P80 HVAC Heater Blend Motor 9134729 replacement ?

[abscate]

They self calibrate either by command from the ECC (couple of button pushes in sequence) or if the battery is disconnected for more than 30 seconds.

Normally, I put no confidence in any answer I give, but I read that this morning while researching this.

Im brimming with confidence from replacing a USBC power port in a Macbook Pro for $30 parts and 25 minutes labor vs 3 weeks and $475 from Apple.

[redc70]

Hey, I don't know if this will help at all. I have a 1999 C70 Cabrio and this screenshot is directly from Vida/Dice. It does not say anything about taking off the dash, just the drivers kick panel and the distribution motor is right there. i understand if yours is different. (probably is)
But mine is a P80 as well.

[cbarbsnv70]

Removing and replacing blend motor 9134729 [which controls defroster air vs other vents, and thus must work to pass Virginia state inspection] on 1998 70 series cars is possible "from below" by removing the driver's side lower trim panel AND the metal crash restraint behind that. 1998 version is a black "crushable" sheet metal piece that looks a little like a muffler. Removing and replacing blend motor 9134729 [which controls defroster air vs other vents, and thus must work to pass Virginia state inspection] on 1998 70 series cars is possible "from below" by removing the driver's side lower trim panel AND the metal crash restraint behind that. 1998 version is a black "crushable" sheet metal piece that looks a little like a muffler.

1999 version is a black pipe with a black styrofoam crash pad.

Both versions can be removed with a combination of 4 bolts and 4 nuts [13 and 12 mm]. 1999 version with pipe has 2 of those nuts way left at door jamb, easiest to access by pulling away the door weatherstrip and using a box wrench [ratcheting type vastly preferred].

In both model years, you will probably want to move the plastic panel that keeps driver's foot out of the heater core to access the lower nut on inboard side of restraint [near driver's knee for left drive car].

Remaining 3 fasteners on motor itself are little Torx T-10 screws.

The blend motor is about an inch tall, and the screws are at the "back" end of the box, so you will need a thin shaft with a little more than an inch reach so you can actually get the torx bit onto the head of the screw while working blind for two of them. A really short T-10 screwdriver might work... most are too long. I used a long/deep hex socket that fit my T-10 Torx bit and taped the bit in so it would not drop out as I was fiddling the tool into place.

I used a 1/4 inch drive ratchet to break the screws loose, but after a half turn, I was able to turn them out [and back in] with my fingers. They are in 25 year old plastic so gentle is important. With those 3 screws removed and not dropped behind the carpet [!!] gently pry the motor off of the plastic scroll wheel.

Carefully remove the electrical connector and let it hang.

Try NOT to disturb the linkage and arm attached to the white scroll wheel if the mechanism is undamaged. This is held by the Torx screw with the red plastic washer under it.

Test the system by putting power back on and the fan to full power [full right on slider]. You should be able to make defrost airflow happen by simply rotating the scroll wheel with your fingers. Putting a piece of paper over the defrost vent will help you see/hear what's up without getting out from under the dash. If all is good so far, remove power at battery, and then get your new motor connected to the electrical plug.

When installing new [or working but used] motor, rotate the white plastic scroll wheel so that the flat side of the hole in the wheel lines up with the flat side on the motor output shaft. Note that the "one screw" end of the motor fits in pointing up and toward the engine. The end held on with two screws is the lower/rear end. Once you have the new motor in place and screws gently tightened, re-apply battery power at battery and start engine. Self-test should happen automatically, and the blend door should self-adjust. When green lights on ECC stop blinking, test defrost [be patient, may take a minute to move everything] and vent. If it worked, shut down motor and re-assemble the knee restraint and trim panel.

1999 version is a black pipe with a black styrofoam crash pad.

Both versions can be removed with a combination of 4 bolts and 4 nuts [13 and 12 mm]. 1999 version with pipe has 2 of those nuts way left at door jamb, easiest to access by pulling away the door weatherstrip and using a box wrench [ratcheting type vastly preferred].

In both model years, you will probably want to move the plastic panel that keeps driver's foot out of the heater core to access the lower nut on inboard side of restraint [near driver's knee for left drive car].

Remaining 3 fasteners on motor itself are little Torx T-10 screws.

The blend motor is about an inch tall, and the screws are at the "back" end of the box, so you will need a thin shaft with a little more than an inch reach so you can actually get the torx bit onto the head of the screw while working blind for two of them. A really short T-10 screwdriver might work... most are too long. I used a long/deep hex socket that fit my T-10 Torx bit and taped the bit in so it would not drop out as I was fiddling the tool into place.

I used a 1/4 inch drive ratchet to break the screws loose, but after a half turn, I was able to turn them out [and back in] with my fingers. They are in 25 year old plastic so gentle is important. With those 3 screws removed and not dropped behind the carpet [!!] gently pry the motor off of the plastic scroll wheel.

Carefully remove the electrical connector and let it hang.

Try NOT to disturb the linkage and arm attached to the white scroll wheel if the mechanism is undamaged. This is held by the Torx screw with the red plastic washer under it.

Test the system by putting power back on and the fan to full power [full right on slider]. You should be able to make defrost airflow happen by simply rotating the scroll wheel with your fingers. Putting a piece of paper over the defrost vent will help you see/hear what's up without getting out from under the dash. If all is good so far, remove power at battery, and then get your new motor connected to the electrical plug.

When installing new [or working but used] motor, rotate the white plastic scroll wheel so that the flat side of the hole in the wheel lines up with the flat side on the motor output shaft. Note that the "one screw" end of the motor fits in pointing up and toward the engine. The end held on with two screws is the lower/rear end. Once you have the new motor in place and screws gently tightened, re-apply battery power at battery and start engine. Self-test should happen automatically, and the blend door should self-adjust. When green lights on ECC stop blinking, test defrost [be patient, may take a minute to move everything] and vent. If it worked, shut down motor and re-assemble the knee restraint and trim panel.