Omix-ADA Heater Blower Motor Resistors

my heater only blows on high. i read your answers saying it could be a bad blower motor resistor or a bad switch. is there a way to check this out before i purchase the wrong product(the switch or the blower resistor0. thanks

Asked by Buster Wideopen from Richmond, "by God" Virginia on

Hello, An A/C blower motor resistor uses resistance to control the speed of the blower motor. It is typical for this type of resistor to control current to the blower motor in all speeds except high. In high speed the resistor is bypassed and power is feed to the motor directly from the switch. So if you only have high that works on the switch then the resistor is bad and needs changed. You can test the resistor with an ohm meter for resistance. Place one lead of the Ohmmeter on terminal 1 of the resistor. Place the other lead on terminal 2 an check reading. If this circuit is open showing infinity on the Ohmmeter the blower resistor must be replaced. Move the lead from terminal 2 to terminal 3 and check this reading against specifications. If this circuit is open showing infinity on the Ohmmeter the blower resistor must be replaced. Move the lead from terminal 3 to terminal 4 and check this reading. If this circuit is open showing infinity on the Ohmmeter the blower resistor must be replaced. The resistance gradually decreases and current increases as the resistor moves from Low to Medium to Medium-High. This increase in current as the resistor moves toward higher speeds increases the speed of the blower motor. Remember resistance and current are proportional. Lowering resistance in a circuit increases the amperage/current and visa versa. Thank you!

Answered by Bob H from Richmond, "by God" Virginia on

Would this correct a blower motor problem when the highest speed is selected but the air output feels like low or barely a medium output?

Asked by M from reno,nv on

Hello, it's a good possibility the blower motor resister is starting to fail. Usually when the resistor goes bad you lose the speed altogether. Like the low speed will stop working and then the medium and then the high will go out. If you still have all three speeds but they don't blow air like they should then it might be the blower motor is going bad. Thank you!

Answered by Bob H from reno,nv on

My heater motor only works on high. Is a blower motor resistor a possible solution?

Asked by John from Stafford, VA on

Hello! Yes, usually when you lose speeds on the heater the resistor is going bad or the switch on the dash is bad. Thank you!

Answered by Bob H from Stafford, VA on