On a 87 Jeep Wagoneer Limited 4x4, 242cid 4.0L, M.O.H.V. - M, it is located under the kick plate on the passenger side. Unscrew the plate and you will see the vacuum motor (which looks like a flying saucer) and to the left of it you will see the resistor. Unplug the four prong wire, and unscrew the two screws holding it in the duct, and lift out. (Takes about ten minutes to remove)
The resistor has power going to it but, the resistor may be burned out and no power is coming out of it. Check for power at the blower motor connection.
It is probably no longer a rsistor but a transitor control model on the fire wall.
You can check the blower motor by unplugging the wire harness and connecting a jumper wire directly from the battery positive terminal to the blower motor. Be very careful to avoid touching the jumper wire to ground to avoid arcing. If the blower motor runs then there may be a blown fuse, bad resistor pack, wiring issues or bad switch.
First check fuse under dash. Then check voltage to blower motor. Then replace resistor under glove compartment. Then move to switch behind dash panel. Then blower relay if no voltage.
Suzukijohn.com
you access the fan blower by removing the windshield wiper motor from the outside of the car.
Assuming your 1987 300E does not have a cabin air filter... The blower resistor/regulator is located beneath the blower motor. Follow the procedure for getting to the blower motor, then remove the motor by diconnecting the red and blue wires. Then remove the motor cradle. There are 2 hex-head screws securing the blower regulator. Remove them, then wiggle the regulator out carfeuuly, toward the drivers side (left) of the car. There is a pin in the bottom of the regulator that fits in a hole underneath it, so you have to work that pin out of the hole below the regulator. The regularor you need is available from several vendors. The Replacement-brand SKU is REPM191902. The original Mercedes part number is 2015400845. IF your vehicle has a cabin air filter, the procedure is similar, but the Replacement SKU for the part is REPM191901. BE VERY sure you order the correct part. The wrong part would be electrically equivalent but has a very different shape and will not fit.
More than likely the blower resistor is bad....I recently ran into this problem in my 91 Vette...Hope this helps!
first thing to check is the fuse
not from the factory
On a 1987 model it is located in the center of the firewall behind a black plastic cover
the heater blower fan is in the heater housing assembly on the passenger side. You need to take out the whole housing assembly in order to access the blower.