1992 BMW 535i - Ventilation Problem

There are several possible reasons why your blower, vent, defrost, AC, and heater might stop blowing air:

1. Blower Motor Failure: The blower motor is responsible for blowing the air through the vents. If the blower motor fails, you will not get any airflow from the vents.
2. Blower Motor Resistor Failure: The blower motor resistor controls the speed of the blower motor. If the resistor fails, the blower motor may stop working or only work at one speed.
3. Fuse or Relay Failure: A blown fuse or faulty relay in the blower motor circuit can prevent the blower motor from working.
4. Control Module Failure: The HVAC (heating, ventilation, and air conditioning) control module is responsible for controlling the blower motor and other components. If the control module fails, it can prevent the blower motor from working.
5. Vacuum Leak: If your vehicle uses a vacuum system to control the vents, a vacuum leak can prevent the system from working properly.
6. Broken Blend Door: The blend door controls the direction of the airflow. If the blend door breaks or gets stuck, the air may not flow through the correct vents.
7. Wiring or Connector Issues: Faulty wiring or connectors in the blower motor circuit can prevent the blower motor from working.

resister either defective or wire incorrectly probably, try running jumper wire to motor to see if it has full speed.

check fuse to blower motor under dash you may have a bad blower motor

The blower, if working sporadically should be replaced or the relay to it. If the blower is on all of the time that the ignition is on, but air isn't coming out of the vents, there is a vacuum motor problem in the heating ventilation and air conditioning system, behind the dash board and hvac panel.

is the fan motor working at full speed
check for blocked cabin air filter
the vacuum only works the vent controls and as you can feel the changes of the vents , it is not vacuum

it's either a fuse or it's a bad blower motor, it could be a bad blower motor resistor but usually you'll get either high or low only, so if you have nothing on any speed, high low etc, and all the fuses are ok chances are it's your blower motor.

I may have had a similar problem, for a long time my blower motor made a loud howling/roaring noise, hard to explain, but I only heard the noise when the blower was turned on. It continued to blow air for a couple years then just quit, the noise it made continued for another 6 months to a year without air-flow. Finally it quit blowing air at all. I eventually replaced the blower motor and no more noise and air flow was restored. Hopefully you already have fixed this because removing and replacing the blower motor wasn't fun.

your blower motor might be damaged.replace the blower motor of the air con.

probably the vent in front of the blower motor lose, check that first.

you might check to see if theres air coming out at the floor level or the windshield level..if so you have a stuck regulator for the air control