A blower motor can become damaged when it’s constantly run at its highest setting. Typical signs of a bad blower motor include loud rattling when the heat is turned on, or a squeal indicating a dry bearing. The motor also may only work on its lowest circulation setting. On the 1999 Chrysler 300M, the blower motor is located on the passenger side beneath the dashboard in the HVAC housing.
Things You'll Need
- Socket wrench set
- Black electrical tape
- Flat-head screwdriver
- Philips screwdriver
- Blower motor
- Torque screwdriver
Raise the hood on the 300M and locate the car battery. Disconnect the negative battery cable with a socket wrench from its post on the battery. Wrap the metal terminal at the end of the cable completely with electrical tape. When you lay the cable down make sure that it’s not in contact with any other metal. The negative post on the battery will have a minus (“-”) symbol next to it.
Open the front passenger door and position yourself so that you can see under the dashboard. Remove the screws holding the instrument panel silencing trim in place. The blower motor mounts directly underneath the panel, and resembles a black tin can with two wires coming from it.
Lift the safety clip on the blower motor’s wiring harness plug. Use a flat-head screwdriver if the clip is hard to lift by hand. Unplug the wiring harness, keeping the safety clip lifted up. Do not pull the harness apart by its wires.
Support the blower motor with one hand and remove all four of its retaining screws with a Philips screwdriver from around its support plate. Slowly lower the blower motor from its position under the dashboard. While you lower the blower motor, make sure that the wiring harness attached to it doesn’t entwine and pull other wires under the dashboard.
Inspect the new blower motor for signs of physical damage. Compare the old blower motor with the new one to be sure they’re the same. Spin the fan cage on the new blower motor in both directions. It should turn freely and smoothly. If it doesn’t or you hear squealing or grinding, the replacement blower motor is defective.
Set your torque screwdriver to 20 inch-lbs. Place the new blower motor back into its housing under the dashboard. Support the blower motor with one hand and fully secure all four of its retaining screws.
Plug the blower motor’s wiring harness back up. (You do not have to lift the safety clip when you reconnect the harness plug. You will hear and fell a small click letting you know the safety clip has engaged securely.) Reposition the instrument panel silencing trim under the dashboard. Return all of the trim's securing screws, and tighten them 1/4 turn past hand tight.
Remove the tape from the negative battery cable terminal. Secure the cable back to its post on the battery with a socket wrench. Shut the hood and start the 300M’s engine. Test out the new blower motor on each setting from low to high.
- "Chrysler LH-Series 1998-2001 (Chilton's Total Car Care Repair Manual)"; Eric Godfrey; 2003
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