Mercedes-Benz ML450 Hybrid Heater Blower Motor Replacement Cost
How Much Does a Heater Blower Motor Replacement Cost?
Heater Blower Motor Replacement Service and Cost
The blower motor is a fan housed in the heating ventilation and air conditioning (HVAC) ducts, normally located behind the glove box. When the heater or air conditioner are active, the blower motor pushes the desired temperature of air through the selected vents.
Inside the HVAC box, the blower motor sits behind the heater core and air conditioner evaporator. When the heater is selected, the blower motor sucks in air, and blows it across the hot heater core, thus providing heat from the vents. Likewise, when the air conditioner is active, the blower motor blows air across the cold evaporator, which blows cold air through the vents.
When the blower motor fails, the air conditioner and heater may still work, and heat or cool may be felt at the vents, but the air pressure will be dramatically decreased. This will occur at all fan speeds, and all temperatures. Another possible symptom of failure is a rattling or grinding noise that comes from the passenger floorboard anytime the heater or A/C is active. This can be caused by broken fan blades, or a faulty fan bearing. This noise may come and go at random, and the fan speed may or may not change the noise.
Driving with a defective blower motor is not the most comfortable option for occupants, but there is no safety risk associated, and the blower motor cannot contact other components to cause damage in most cases,
Blower motors tend to fail frequently in high mileage vehicles, but their failure does not depend on mileage. Age can be a factor as the plastic fan blades become brittle over time. The amount of use a blower motor receives may also be a factor. Also, debris entering the HVAC box can destroy a blower motor regardless of mileage or age.
Heater Blower Motor Replacement Repair Information
The servicing technician will perform a series of tests that will lead them to the blower motor diagnosis. If the blower motor is making a grinding or rattling noise, it will be removed first for inspection, and if defective, it will be replaced. If the blower motor not blowing air, the technician will first find and inspect any related fuses. Afterwards, the blower motor’s electrical connector is inspected to determine if power is reaching the blower motor. If power reaches the blower motor, and the blower does not function, it will be removed, bench tested with an external power source. If the blower motor fails to operate under direct power, it will be replaced.
If the blower motor must be replaced, either the glove box or lower cover will be removed from the dashboard. This will grant access to the HVAC duct box, and the blower motor service cover. The service cover is removed, and the blower motor is disconnected electronically. Finally, the blower motor retaining screws will be removed, followed by the blower motor. Installation will include installing the blower motor resistor into the blower motor, followed by the reverse order of operations for removal. The technician can then test the function of the blower motor, and confirm the customer complaint has been resolved.
If the blower motor is making noise, there is no issue using the air conditioner. The motor will eventually fail once the noise has started, but until the vehicle is repaired or the blower motor fails, further use should not complicate the issue. The blower motor resistor can cause similar symptoms, but the fan would more than likely work on one or more settings until the resistor fails. When all fan speeds are not functioning, the blower motor will be suspected.
The moderately skilled DIYer can accomplish this diagnosis and repair. A basic understanding of a series electrical circuit, a few basic tools, and a digital voltage meter are all that is required. It is important that the DIYer understand the testing procedures for the blower motor circuit, as failing to properly test the blower motor may lead to unnecessary costs.