Look in the e38 forum and it will give you a detailed account of how to do itType your answer here...
The heater blower motor can be found beneath the passenger side dashboard. Remove the wiring harness from the back of the blower motor. Remove the blower motor retaining bolts. Reverse the process to install your new blower motor.
it's the blower motor
The cost of a new blower motor for a 1991 Honda Civic ranges between 60.00 and 80.00 as of 2014. Labor to install ranges from 50.00 to 75.00 an hour.
Open the bonnet, remove the scuttle cover, wiper motor, and finally blower motor.
faulty blower module. Under hood not far from blower motor
The blower motor is located on the passenger side up under the glove box.
The 1991 Honda accord blower motor resistor is located on the firewall in the engine compartment. The blower motor resistor will be on the passenger side of the firewall.
blower motor resistor thermal limiter is blown. Replace the blower motor resistor.
take the plastic of from the passenger side underneath the dash.. the blower motor is up under their tucked away.. but you can get it after a few hrs of work..
behind the engine, next to the brake booster, a ring of 7mm screws finess it out wriggling it a little. replace the control module at the same time!!
Behind the power steering pump on the passenger side.The pump will have to be removed in order to remove the blower motor.
Many are in the air duct near the blower motor.