Possible malfunctions of the heater fan motor, their causes and solutions
| Cause of malfunction | Remedy |
| Heater fan motor does not work | |
| Damaged wires or oxidized wire connections F5 fuse blown in the mounting block Damaged heater switch - no voltage applied to heater switch output terminals Hanging or wear of the brushes of the electric motor of the heater, a break in the armature winding or contamination of the collector Short circuit on «mass» armature windings - when the heater motor is turned on, the fuse blows | Check and repair connections. Replace damaged wires Replace fuse F5 in the mounting block Check heater switch, replace if necessary Check the heater motor, repair or replace it Replace heater motor |
| Heater fan motor only runs at one speed | |
| Damaged wires or oxidized wire connections Damaged heater switch Auxiliary heater switch resistor burned out | Replace damaged wires, clean wire ends Replace heater switch Replace auxiliary heater switch resistor |
| Heater fan motor armature rotates slowly | |
| Pollution or oxidation of the collector, wear of the heater brushes Interturn short circuit in the heater armature winding Seizure of the heater armature shaft in the bearings | Clean the collector, replace the heater brushes Replace heater motor Replace heater motor |