The heater unit hangs from the underside of the dash. Four small (maybe 7mm) nuts and large diameter washers hold it on. First you need to drain the coolant. The center console has to be removed. Then you can disconnect the operating cables from the heater valve and the damper. Disconnect the coolant hoses and then remove the heater valve. Disconnect the 3 wires for the fan motor, one is a ground. Disconnect the two vent tubes from either side of the heater. Unscrew the 4 little nuts that hold the heater unit to the dash. I think that a 1/4" socket set with extensions makes this easier. The nuts may be rusty and you may have to squirt them with PB Blaster or similar.
The heater can now be wiggled out on the passenger side.
When you take the heater unit apart to get at the motor, take a picture or make a sketch of the position of the damper arms and linkage before you remove them. It will be a big help on re-assembly. If the motor is locked, there is a possibility that it has burned up if it was switched on for any length of time. It should be obvious if it is. Otherwise, soak the motor shaft bushes with PB Blaster and spin it until it loosens up. I once removed the fan, put the motor in a vise and attached a drill motor to the shaft. That was about 6 years ago and the motor is still running strong in my Spider.
Ed Prytherch
