It’s a hot day. You just exited an air-conditioned home or office. You make a beeline to your car. Then, you quickly unlock it, open the door, and enter a hot and stale air filled vehicle. You start your engine and quickly turn on the AC expecting cool air to start flowing. You wait. Only warm air is flowing. Next, you rev the engine a bit expecting the air conditioning to kick in and start cooling the cabin. Nothing. Still no cool air. You think: Where is my cool air and what is going on with my car AC system?
There was a time when air conditioning was a special feature in a vehicle. According to Automobile Magazine, air conditioning systems in cars started in 1940 when automobile manufacturer Packard introduced the first factory-installed climate control system in one of their vehicles. Today more than 99% of all vehicles include air conditioning. The technology has come a long way since the 1940s and your vehicle’s air conditioning system is more complex than you may realize.
Unfortunately, this means that when your AC is not functioning properly there are often a number of possible reasons for the failure. Some root causes are incredibly simple; others are more complicated.
Air conditioning basics: Know the 5 key components
Before we review why your car’s air conditioning might not meet your expectation, let’s review the basics of how a vehicle’s AC system works. There are five key components to your vehicle’s air conditioning system.
- Refrigerant is a safe and specially formulated gas that transforms hot air into cold air.
- AC compressor turns refrigerant gas into a liquid.
- Condenser dissipates the heat that is produced from the refrigerant once it has been compressed into a liquid. It operates like the radiator for your air conditioning system.
- Expansion block is responsible for converting refrigerant liquid back into a gas. As the liquid converts back into a gaseous state, it cools.
- Evaporator core – freshly evaporated refrigerant travels through an evaporator core, forcing the cooled air into your vehicle.
The average AC system is “closed” meaning that it is a sealed system and should be maintenance-free. However, modern air conditioning systems can be sensitive. Each component plays a critical role in the air conditioning process and there are many possible reasons for your AC to fail.
5 most common problems that can cause your air conditioning to fail:
1. Refrigerant Leak
This is likely the most common issue that can plague your AC system. Most of the items in your AC system are made from very thin-walled aluminum, in addition to rubber or neoprene o-rings and gaskets. All it takes is a very tiny pinhole to form in the system to cause leakage.
These small holes are very hard to see with the naked eye. In order for an automotive technician to find any pinhole(s), they inject a reflective dye into the system. When the dye finds itself exiting the system through any pinhole or crack, the use of a blacklight will highlight the areas that need to be fixed. Depending on the size of the leak, a technician may have you drive the vehicle for a few days and come back to find the hole.
2. AC Compressor and Clutch Unit
This is an important part of your AC system. The AC compressor and clutch unit is responsible for taking a low-pressure refrigerant liquid and converting it into a high-pressure gas. There are several elements to a properly functioning compressor.
- Refrigerant Pressure Level – Refrigerant needs to be a certain pressure to make the compressor turn on.
- Power Supply – The power supply controls the unit itself and makes the clutch turn on and off.
- Drive Belt – The drive belt spins the unit and compresses the gas.
Your automotive technician will investigate each of these components for proper operation. In the event each are operating correctly, the compressor itself has likely failed and needs to be replaced.
3. Condenser/Receiver Drier
This is the radiator for your AC system. It usually is located in the front of your vehicle and sits ahead of the vehicle’s engine radiator. It takes in air while you are driving and cools the hot gasses before filtering the refrigerant and sending it back into the system. The condenser/receiver drier usually requires its own dedicated fan to cool the refrigerant when your vehicle is not moving. It is very prone to leaks from road debris like pebbles, rocks, and more.
4. Evaperator Core
This is another miniature radiator, located underneath the dashboard of your vehicle. The evaporator core delivers cool refrigerant to the cabin. The blower motor takes the ambient air and pushes the air across the evaporator into the cabin of the vehicle. The evaporator core is an inexpensive part when compared to other AC components. However, because of its location, it often takes several hours to replace.
5. Blower Motor
The blower motor sends air over the coils of the evaporator core, blowing cool air into the cabin of your vehicle. There are two pieces to the blower motor: the blower motor itself and the blower motor resistor. The resistor is what takes the voltage to the blower unit and makes it operate at higher and lower speeds. For example, if you cut the voltage with resistance to half of normal, your blower motor will blow on “medium.” If your air and heat do not blow at all, the motor is typically the issue. If your AC only operates at certain speeds, then the resistor is the likely culprit.
Since AC systems are complex, Openbay recommends having a certified technician troubleshoot the system when it is not meeting your expectations. Once your car’s AC system develops a problem it can harm other parts, making your repair much more expensive. A trained automotive service professional is equipped to properly service today’s sensitive air conditioning systems, keeping your car running trouble-free longer.
Does your AC need service? When you need quality automotive services such as air conditioning repairs, brake services, oil changes, engine repair, suspension, and more, give Openbay a try. Openbay is an online marketplace connecting consumers in need of service with quality local auto repair service centers.
Written by Rob Grant, Automotive Operations Manager at Openbay. Rob is an ASE Certified Technician and frequent contributor to this blog, specializing in all things automotive service and repair.