How do I know if my blower control module is bad?

Author: Telly Hintz  |  Last update: Saturday, April 5, 2025

One of the most telling signs is if the blower motor isn't blowing air at all or the airflow is weaker than usual. If you set your AC or heater to the highest setting and barely feel a breeze, your blower motor control module could be the issue.

How do I know if my blower control switch is bad?

A bad control switch won't be able to accurately change your A/C system's settings. The button will most likely refuse to respond even if you try to increase the fan speed.

How to tell if a fan control module is bad?

The fan stops blowing air: Anyone who has driven a car will realize that there is a problem when the fan isn't running when the air conditioning is on. If the cooling fans are not running at all, then this may be a sign that the fan control module is damaged.

What are the symptoms of a bad HVAC control module?

Since the module regulates the entire AC system, inconsistent cooling, out-of-date software, and uneven air distribution are typical signs of a broken AC control module.

What does a blower control module do?

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.

How Do I Know If My Blower Motor Control Module Is Bad?

How to tell if a blower motor control module is bad?

  1. Symptoms of a Bad Blower Motor Control Module.
  2. A blower motor control module is crucial for your vehicle's HVAC system. ...
  3. * No Airflow or Weak Airflow.
  4. One of the most telling signs is if the blower motor isn't blowing air at all or the airflow is weaker than usual. ...
  5. * Intermittent Operation.

How much does it cost to replace a blower module?

Replacing a furnace blower motor costs $560, on average. Depending on the size and type of motor, most people pay $300 to $900. The average blower motor replacement cost is $560, but the final price depends on labor fees, as well as the cost of the parts.

What are the symptoms of a bad control module?

Symptoms of a Failing ECM
  • Check Engine Light (CEL) Illumination: ...
  • Poor Engine Performance: ...
  • Reduced Fuel Efficiency: ...
  • Stalling and Rough Idling: ...
  • Transmission Issues: ...
  • Increased Emissions: ...
  • Inconsistent or Non-Functioning Gauges: ...
  • Difficulty Starting the Vehicle:

How do I reset my HVAC module?

In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.

Which of the following is a common symptom of a faulty blower motor?

Strange Rattling, Clanking, or Screeching

One of the first signs you may notice when there's an issue with the blower motor is a strange noise coming from the indoor unit or air handler.

What does a fan control module do?

The cooling fan module is a complete electrical subsystem. It is able to set the right speed for the fan.

How do I know if my fan regulator is bad?

1. The fan won't turn on at all: This could be due to a faulty connection between the regulator and the mains or the motor. Check for loose wires at the regulator terminals and the fan's connection box.

What does a HVAC blower control switch do?

This switch is a component of a furnace system that determines when the furnace's blower assembly for hot air turns on and off. In simpler terms, this is what determines when hot air should be blown through your ventilation system to warm your home to the temperature that you have set.

How do I know if my blower relay is bad?

Symptoms of a Bad Blower Motor Relay

On platforms where the blower is directly controlled by the switch rather than a module, the relay will cause the blower not to work at all, which means there will be no airflow across the evaporator, and the effect will be the same as the A/C not working at all.

How do I reset my blower switch?

How Do I Reset the Blower?
  1. Turn off the circuit breaker powering your HVAC system.
  2. Unscrew the blower cover.
  3. Give the blower time to cool down completely before proceeding.
  4. Push the reset button (typically a red button behind the blower motor).

What are the symptoms of the HVAC control module?

Tips to Identify Climate Control System Issues
  • Inconsistent or No Air Flow. ...
  • Inadequate Cooling. ...
  • Inadequate Heating. ...
  • Strange Noises. ...
  • Unpleasant Odors. ...
  • Water Inside the Vehicle. ...
  • Fluctuating Temperatures. ...
  • Poor Defroster Performance.

Where is reset button on HVAC unit?

Power down your AC: Turn off your AC unit and unplug it from the power source. This will ensure that you stay safe while working on the unit. Locate the reset button: Most air conditioning units have a reset button located near the outside unit. It is usually a small button located inside a small hole.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

What happens if control module fails?

Because the ECM is responsible for ignition (spark) timing and fuel injector operation, a faulty ECM can easily result in a vehicle that cranks but doesn't start. A bad ECM may also result in a no-crank-no-start condition if the module is integrated into the starting and/or anti-theft circuits.

How do you diagnose a bad module?

Here's a quick process:
  1. Scan for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to detect issues.
  2. Check for Electrical Problems: Inspect wiring and connectors for damage or corrosion.
  3. Test Sensors: Ensure sensors relaying data to the ECM are functioning properly.

How much does it cost to replace a control module?

The cost for the new ECM will typically be around $800, with labor around $100, bringing the average total expense for an ECM replacement to approximately $900 before taxes and fees. This can increase depending on the shop you go to or the type of car you, running as high as $2,000. Looking to sell a problem car?

How do I know if my blower motor is bad?

How do you know if your furnace blower motor is bad
  1. Unusual Noises. Screeching or Squealing. ...
  2. Weak Airflow. Insufficient Heating. ...
  3. Motor Overheating. Excessive Heat from the Furnace. ...
  4. Inconsistent Performance. Start-Stop Issues. ...
  5. High Energy Bills. ...
  6. Age and Wear.

How long do AC blower motors last?

Blower motors are designed to last just as long as your furnace itself, anywhere from 10 to 20 years. Just as with any HVAC system, the better maintained and serviced your equipment is by experienced HVAC technicians the longer it will last and the fewer repairs you'll face.

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