Blower motor replacement on HGV cabs: diagnosis and fitting
The blower motor is an electric motor driving a centrifugal fan inside the cab heating unit. When the motor fails, airflow through the cab system stops entirely. Heat may still be present in the heater matrix and cooling from the AC may still be operating, but without fan movement neither reaches the cab effectively.
Before replacing the motor, confirm the fault is in the motor itself rather than the blower control circuit or the blower resistor pack. The resistor pack controls fan speed by varying the voltage to the motor. A failed resistor pack causes no airflow at some speed settings but normal airflow at others. A failed motor causes no airflow at any speed setting. Blower motors on HGVs run on 24V.
Frequently Asked Questions
How do I test a blower motor on an HGV?
Remove the blower motor connector and apply 24V directly to the motor terminals. If the motor runs, the fault is in the supply circuit, the blower resistor, or the switch. If the motor does not run with direct supply, the motor has failed.
What is a blower resistor and how does it relate to the blower motor?
The blower resistor pack controls fan speed by reducing the voltage supplied to the motor at lower speed settings. If the resistor fails, the fan may only work on the highest speed setting or may not work at lower settings. The resistor and the motor are separate components and fail independently.
Does blower motor replacement require the cab dashboard to be removed?
Access varies by cab design. On some HGVs the blower motor can be removed from inside the cab behind a trim panel. On others it requires removing the heater box from the bulkhead. Check the workshop manual for access procedure before starting the job.
Does Truckstop Group stock blower motors for all HGV makes?
We stock cab blower motors for the main HGV makes. Call us on 01527 598 000 with your chassis number to confirm availability for your specific cab and HVAC configuration.
