Summer heat waves seem to be the time when something goes wrong with our air conditioning systems in our cars. At Eurofed Automotive, we are experts at fixing automobiles, including HVAC systems. In this article, we’ll discuss some problems that happen with your vehicle’s HVAC system as well as some tips to fix them.
Common Heating and Air Conditioning Problems in Automobiles
The blower motor is a mechanical device that controls the fan in the HVAC system. The motor, like most mechanical devices, is subject to wear and tear over time. Living in climates where temperatures can be extreme or changing frequently can mean more opportunities for the blower motor to wear out.
Resistor or Climate Control Module
Depending on your car, you either have a resistor or climate control module. If the fan in your car has five or six set speeds, your car has a resistor. A resistor is an electrical unit that controls the speed of the fan. In some cases, the resistor will fail and your fan will no longer have multiple speeds; it will simply have on and off. In other cases, electrical issues such as a blown fuse can cause the resistor to stop working.
The thermostat controls the temperature in the HVAC system. In most cases, when this fails, you will lose the ability to heat or cool your car. Before it fails, you may find that it works some of the time, but not all of the time. You may find the cool air isn’t as cool as it should be or the heat isn’t as warm as expected. This won’t affect the blower in the HVAC system, but it is just as frustrating.
Diagnosing Resistor Failure from Blower Motor Failure
There is one way to determine if the resistor is failing or if the blower motor has failed. Unfortunately, if either one is in the process of failing but hasn’t completely failed yet, some of the symptoms can be identical. If you have a climate control module in your vehicle, this test will not work. However, if your vehicle has an adjustable blower, then this test may give you some helpful information.
First, turn off your car and sit in the driver’s seat. Turn the AC off and turn the fan off. Now turn the car on but don’t start the engine. Usually, that is the first stop on the key start or a short click on the automatic start vehicles.
Now, turn the fan on its lowest setting. Listen closely, and with your free hand, feel the air pressure. If you can hear the fan or feel a change in air pressure between the off position and the first setting, make a note of this. If you cannot hear or feel anything, then the blower motor is likely the problem.
Next, turn the fan up to a higher setting. If you can feel the increase in pressure and hear the change in the fan speed/power, then the problem is probably not the resistor. If you hear any kind of grinding, whining, or clicking sounds, the problem is likely the blower motor. If you did not feel any change between the first setting and the second setting of the fan, then the problem is likely the resistor.
Unfortunately, the above diagnostic method is not foolproof. In many cases, issues with the HVAC system happen in sets. This is because the resistor will have to work harder when the blower motor is starting to fail, and the blower motor will have more stress placed on it when the resistor is starting to fail. The best thing you can do when you start to notice a problem is to bring your car in for differential diagnosis and find out exactly what is going wrong before anything else is impacted.
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