The HVAC blower motor resistor or BMR for short, controls the speed of vehicle's blower motor. A malfunctioning blower motor resistor will cause a poor cabin cooling or heating condition. It can also cause poor windshield defrosting or de-icing, reducing driver visibility. The blower motor should be checked for amperage draw per the manufacturer's specification and cabin air filters, if equipped, should be replaced. Designed and manufactured to meet or exceed original equipment manufacturers' specifications for performance and durability.