Sign | Probable Cause | Remedy |
| No air flow | It does not work the fan motor | Check the electric power supply circuit of the engine |
| The fan motor is running | Check the following items:
- Clogged air channels; - Clogged fan output; - Clogged radiator or heater hose; - Faulty air damper; - Faulty control cable. |
| Inadequate flow of heated air | Do not change the fan speed | Check the electric power supply circuit of the engine |
| Fan is working properly | Check the following items:
- Clogged air channels; - Clogged fan output; - Incorrect position of the choke. |
| The compressor is not turned on even though the condenser fan runs | Check the electric power supply circuit of the engine |
| The compressor and condenser fan are not included | Check the electrical power supply circuit of engines |
| Only the condenser fan is not included | Check the electric power supply circuit of the engine |