Blower Motor Blows When Car Is Turned Off- What Should Be Wrong?

On hot summer days like these, long-distance trips cannot be comfortable without cool air flowing from the blower fan system.

But after you get home, turn off the power supply and realize something is wrong: The blower motor blows when car is turned off! So, what happened to your 4-wheeled friend?

Unfortunately, it is a sign that your car needs repair as soon as possible.

If you don’t know where to start, my article is for you! Besides the top causes for this problem, it also provides extremely good repair and warranty tips.

Blower Motor Blows When Car Is Turned Off- Top Causes 

blower motor blows when car is turned off

The causes of the AC fan still running when car is off mainly come from the ignition system and the blower system.

Due to the close connection of the parts of the systems, if just one part has a problem, the whole system will be adversely affected.

Here are the 5 most common causes I have put together for you.

Bad Ignition Switch

Faulty ignition switches are one of the top causes that any driver should pay attention to.

When this part has a problem, the blower motor cannot receive the correct operating signal, leading to the phenomenon that the fan still blows regardless of whether the car engine is running.

Fortunately, replacing the bad ignition switch with a new one will return to normal.

Blower Motor Resistor Problem

The blower motor resistor is an electrical component in the HVAC system. It is responsible for controlling all fan speeds through the resistor.

A faulty blower motor resistor cannot send the correct signal to the fan motor, so the car blower motor won’t turn off anyway.

Usually, the most common remedy is to repair and replace the blower resistor.

Bad Blower Control Module

The module acts as a computer that controls the fan speed of the vehicle’s air blower motor. Thanks to it, air can circulate throughout the car’s cabin and all the cooling fans.

Of course, any problem with the blower control module means the airflow can no longer work properly.

In case of malfunction, you will find it impossible to control the operation of the air blower system.

Shorted Wire

Over time, the fan system wiring can become frayed and broken.

It will lead to a short circuit and block the only signal transmission path of the motor to the blower motor, resulting in inconsistent operation between these two parts.

Fortunately, although this frequency is very painful, this problem is easy to fix. You need to re-solder broken or replace wires, and your vehicle will return to normal in no time.

Stuck Fan Relay

If you have checked the above 4 parts and still do not find any abnormality, the problem may come from the least expected part – the stuck fan relay.

When it is stuck in the on position, it will keep the blower motor in its running state.

It would be best to try disconnecting the battery for a few minutes to reset the relay. If the problem is more serious, replacing the relay will be the most reasonable choice.

How To Fix When My Car Is Off But The Ac Is Still Running?

ac fan still running when car is off

No one wants the blower engine of their vehicle to suddenly keep running while turning off the engine for a long time.

But if this misfortune happens to you, first take a deep breath and calm down. Follow my instructions below to identify the problem’s source and take the most appropriate remedial action

Check to see if the vehicle’s exhaust fan is operating in continuous mode. If yes, change it to “intermittent” mode and test again.

Check all power lines connecting the blower motor system if the problem persists. Once looseness is detected, use a wrench and screwdriver to re-tighten the wire connectors.

You need to reconnect broken wires and even provide new replacements if required.

Check the fuse box again and make sure it’s still working properly. If nothing unusual happens, the source of the problem must be in the fan system.

The best fixing method is to contact the repair center for an appointment with the mechanical experts as soon as possible.

How To Keep My Blower Motor Working Properly? 

Follow the tips below, as they can prevent the fan from running even though your car’s engine is off.

Ensure vehicle batteries are always properly charged and operating in ideal operating conditions. In case of a dead battery, replace it with a new one immediately.

Regularly check the wiring connected to the car’s blower motor to deal with corrosion or damage promptly.

Regularly service the blower fuses and blower motor relays to ensure they are in good working order.

Whenever routine inspection reveals any potential problem, deal with it immediately.

Ignoring and continuing the journey causes problems with the blower motor and adversely affects the surrounding systems.

How To Diagnose Intermittent Blower Motor?

mercedes blower motor stays on with ignition off

If your newly purchased car suddenly has problems with the blower motor and intermittent operation, that is a sign of dead spots in the connection.

Determining dead spots is difficult for non-mechanic drivers. But don’t worry; you can still do it at home with an oscilloscope.

First, securely clamp the oscilloscope into the sling wire connected to the resistor. Then start the car and turn on the blower.

You will need to adjust the blower settings depending on the type of oscilloscope in use. Observe closely the fluctuations of the waves or ripples in amperage displayed on the screen.

The larger the Ribble, the greater the potential for interference. If you notice a large ripple in the amperage, your blower system has a dead spot or electrical issues.

Faqs

Why Does My Car Ac Fan Turn On And Off?

The air conditioner’s inability to operate properly is a sign that some problem is occurring with the car’s AC unit. Specifically, you can refer to the following reasons:

  • The air filter is clogged with dirt and debris, preventing the condenser coils from getting the required air.
  • Inadequate amount of Freon.
  • Electrical issues, such as the compressor, condenser, fuse, relay, etc.
  • Problems with the air system and blower, including the control valve, switch, blower motor, air intake, belts, cooling fan, etc.

How Much Does It Cost To Fix The Ac Fan Still Running When The Car Is Off?

In my experience, it’s usually cheaper to replace a blower motor than it is to repair one.

Of course, it depends a lot on the type of vehicle you own, the problem’s severity, and the mechanics’ moral values.

Typically, replacement costs will range from $50 to $100, plus about $100 in labor. After 6 hours of repair, your vehicle will return to normal working condition.

How Long Does A Blower Motor In A Car Last?

Some blower motors can be serviced without any problems, along with the age of the vehicle. But some products fail in the first few years due to various reasons.

Determining when your car’s blower fan deteriorates is difficult because it depends greatly on your maintenance regime.

Some Last Words

Any journey or summer picnic will be perfect only if your blower motor operates in ideal condition.

But if the blower motor blows when car is turned off, don’t worry because you now have enough experience to handle and prevent this problem from happening again.

This article provides you with all the most useful information related to the cause of the problem with the blower motor and how to fix it.

And now, it’s time to service your four-wheeled friend! Good luck!

Leave a Comment