The blower motor resistor is responsible for controlling the blower motor speed. In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.
What happens when blower motor resistor goes bad?
A bad or failing blower motor resistor hampers the efficiency of the heating and air conditioning system. A working resistor can shift between speed settings according to the user’s preference. If one of the resistors is burned out, the only speeds that will work are the speeds above the burned out resistor.
What are the symptoms of a bad blower motor?
- Poor or Airflow from Air Vents. This will be the first and most obvious sign your blower motor has a problem. …
- No Airflow At All From Vents. …
- Skyrocketing Energy Bills. …
- Strange Noises When You Turn on the Heat. …
- Overheating Blower / Weird Smells.
How do I know if my blower motor resistor is bad?
Problems with a blower motor resistor are common in many cars. The most common symptom of a failed blower motor resistor is when the heater fan only runs at the highest speed setting (4 or 5) and doesn’t work at low speeds. In some cars, a failed blower motor resistor can cause a heater fan to stop working completely.Should I replace blower motor and resistor?
There is still a chance that the blower motor control could be faulty, but if the control knob feels good and all the fuses and relays are good, chances are you need to replace the blower motor resistor.
Why does my blower motor resistor keep burning out?
Trent, one of the biggest reasons for blower motor resistors to have shorten life is actually because of faulty blower motor drawing too many amps, some times melting wires/plugs, heating up resistors shortening their life.
Can a blower motor resistor be bypassed?
Blower resistors are made of several resistors with different resistances. … In the highest speed state, the blower resistor is bypassed completely and the fan is connected directly to the car’s battery, which allows maximum current through the motor.
Can you drive without a blower motor?
Your car’s blower motor is not only necessary for the operation of your air conditioner. Without a functioning blower motor your engine runs the risk of overheating. … Start car and see if blower motor works. If fuse blows again, check for loose circuits.Why does my blower motor fuse keep blowing?
Blown fuses If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Any sort of electrical spikes or excessive current from a bad relay will blow the fuse and cut power in order to protect the system.
Can you test a blower motor resistor with a test light?Unplug the blower motor and test for power using the 12-volt test light in the same manner as explained in Step 1. … If there is power indicated on high blower speed, but not low or mid range, the problem is the blower resistor.
Article first time published onWhat is blower motor relay?
In a blower motor, the relay supplies the power that allows the fans to circulate warmed air. Essentially an on/off switch, the blower motor relay’s reactions start and end the heating process in HVAC systems by controlling the flow of current between the power source and the motor.
What would cause a resistor to burn up?
Burning of Resistor When a resistor has been overloaded with voltage exceeding its power rating, the resistor will become very hot to touch, darken considerably and possibly even melt or catch on fire. … However, it may be functioning with less resistance than it was originally designed for.
Can you bypass a resistor?
All current will bypass the resistor and travel through the short. The voltage across the 100Ω resistor is going to be zero. The 100Ω resistor is not impacting the circuit.
What causes a resistor to go bad?
Resistors rarely fail when the circuit is designed properly, but under overload conditions (such as the failure of a component elsewhere in the circuit that puts a high voltage across the resistor) resistors typically fail by becoming an open circuit (after becoming very, very hot to the point of incandescence).
Why does my blower motor work sometimes?
When a resistor fails, the fan will often run only at higher speeds or the highest speed, no matter what fan speed is selected. … When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage.
Does the blower motor resistor control heat?
The blower motor resistor is an electrical component that is a part of the vehicle’s heating and air conditioning system. It is responsible for controlling the blower motor’s fan speed. … A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system.
Is there a fuse for the heater blower?
Many vehicles have two fuses for the blower motor, one in the interior fuse block and the other under the hood. … The blower motor is usually under the dashboard on the passenger side.
Why will a blower run on the on position and not on auto?
Other Blower Fan Won’t Run Problems The fan will run and blow warm air but only in FAN or FAN ON mode – delivering heat – but NOT in AUTO mode. This is a bad temperature sensor in the unit; replace the fan limit controller.
Why does my car air conditioner only work on high?
If your air conditioner works on high, it is a very specific issue. It can mean that there is a problem with the blower motor, the control board, or the thermostat. However, we still do a full diagnostic check-up to ensure that all of the switches, wiring, and fuses could not be causing the same issue.
How much does it cost to replace a motor blower?
Replacing a blower motor costs $450 on average with a typical range of $250 to $800. With a warranty, you might pay as little as $150 for labor alone. For high-end models, like those with large motors or access issues, you might pay as much as $2,000.
How do you know if a resistor is bad?
Your meter will read it as open circuit (infinite ohms). Or maybe it’s a 0.1 ohm current sensing part. Your meter will read it as a short circuit. If it’s a larger resistor with leads and it looks and smells burnt, assume it’s bad.
How do you reset a furnace control board?
- First, turn off the power supply to the furnace by turning off the breaker in the circuit box.
- Locate the reset button on the furnace and press it to reset the furnace. …
- If the button is popped up, press it down.
- Return the cover to the blower compartment and turn the power on.
How do you reset an AC high pressure switch?
High-pressure switches are available with either an automatic or manual reset. An automatic reset will automatically restart the compressor when the pressure falls to a safe value. A manual-reset high-pressure switch needs to have an operator manually press a reset button in order to restart the compressor.
