Other than a defective motor, a bad switch or blower motor resistor assembly can cause an inoperative heater blower motor.
Car problem reports
Problem with your car? See what our experts say or submit your own.
Most reported 1990 Mercedes-Benz 560SEL problems
On high mileage vehicles, rear spring wear may cause the rear end to sag.
The fuel pump and/or fuel pump relay can fail, causing the car to crank over but not start. Proper diagnoses will be necessary to confirm if the pump or relay is at fault.
One or more door windows may stop working due to a failed window regulator. Replacement of the failed regulator will be necessary to correct this concern.
Power steering hoses and components can develop leaks.
A rough running motor or lack of power can be caused by a failed distributor cap or rotor, ignition wires (or their resistors), or valve cover gasket leaks. If the valve cover gasket leaks, oil can pool where the ignition wire resistor connects to the spark plug. The resistor can fail and the spark plug may not fire because of a short circuit through the oil.
It is not uncommon for the idle air compensator to get stuck in one position, resulting in the engine idle speed (rpm) being too high or too low. Replacement of the failed compensator may be necessary to correct this concern.
Internal leaks and a stuck level control valve can cause problems with the load leveling suspension in the rear; the vehicle may ride harshly.
The tie rod ends, idler arm, and/or drag link components of the steering linkage may wear prematurely. Please keep in mind the wheel alignment should be checked and adjusted when any of these items are replaced.
Valve stem seals may wear and cause the engine to burn oil. this can contaminate the catalytic converter and cause it to fail.
A vibration felt through the center floor of the vehicle can be caused by cracked and/or shredded driveshaft flex discs, resulting in excessive driveshaft movement. If not repaired, damage to the driveshaft center support bearing, transmission, or differential can occur.
High mileage vehicles may develop a transmission fluid leak from one or more of the oil seals.