Car cabin feeling like an oven?
AC not helping at all?
A working AC is essential for cooling your car’s interior. When it fails, your cabin will resemble a slow cooker, roasting you and your passengers as you drive.
If you can’t help but wonder: “Why is my car’s AC not blowing cold air?”
We’ve got your back!
To help you avoid getting cooked this summer, we’ll explain the causes of your AC issue, how to diagnose it, and how much this auto repair costs.
This Article Contains:
- How Does Your Car’s AC System Work?
- 10 Concerning Reasons Why Your Car AC Isn’t Blowing Cold Air
- How to Diagnose and Fix Car AC Problems
- 3 FAQs about Car AC Systems
How Does Your Car’s AC System Work?
Your car’s air conditioning system cycles a chemical called refrigerant through a closed loop to remove heat from the air and cool the cabin. Here’s how:
- The compressor pressurizes the refrigerant, converting it into a hot, high-pressure gas. This gas flows into the condenser, releasing heat and turning into a high-pressure liquid.
- Next, the cooled liquid refrigerant passes through an expansion valve, quickly dropping its pressure. This sudden pressure drop causes the refrigerant to become very cold.
- The cold refrigerant enters the evaporator coil inside the dashboard. As warm air blows across the evaporator, the refrigerant absorbs heat, cooling it before it enters your cabin.
- After absorbing heat in the evaporator coil, the refrigerant evaporates into a low-pressure gas and returns to the compressor.
Now that you know how your car’s air conditioner functions, let’s examine why yours isn’t working.
10 Concerning Reasons Why Your Car AC Isn’t Blowing Cold Air
Several problems, from electrical issues to a clogged air filter, can cause air conditioner problems. Let’s take a look:
1. Low Refrigerant
Refrigerant absorbs and releases heat in the AC system. However, damaged hoses and O-rings can cause a refrigerant leak.
In case of a low refrigerant level, heat won’t dissipate properly, and the AC will blow warm air.
2. Fan Motor Failure
The fan motor (blower motor) circulates air through the AC system.
If it fails (often due to an electrical issue), the condenser can’t efficiently dissipate heat. This usually results in the AC blowing hot air, especially when the vehicle is stationary or moving slowly.
3. Faulty AC Compressor
The compressor pressurizes refrigerant, allowing it to circulate through the AC system to cool the air in the evaporator.
However, a faulty compressor can’t properly compress the refrigerant. This prevents it from cooling the air in the evaporator.
4. Blocked Cabin Air Filter
The cabin air filter prevents debris from entering the cabin to maintain clean airflow.
But, it can get blocked over time, restricting conditioned air from flowing into the cabin and reducing cooling efficiency.
5. Wiring or Electrical Problem
An electrical problem, like a blown fuse, corroded connector, or broken wire, can disrupt the AC system’s electrical supply and prevent it from functioning correctly.
6. Blocked or Broken Condenser
After the compressor squeezes the refrigerant into a hot, high-pressure gas, it flows into the condenser coil. Here, cool air flows over the condenser’s thin metal fins, cooling the refrigerant.
However, a blocked condenser can’t properly release heat, resulting in a lack of cooling.
7. Defective AC Condenser Fans
Condenser fans cool the refrigerant by forcing air through the condenser coil, especially when the vehicle is idling or moving slowly.
If the fan motor fails, blades break, or electrical connections short, the broken condenser can’t cool the refrigerant, and the AC blows hot air.
8. Faulty AC Controls
AC controls (such as knobs, buttons, and digital panels) signal the system to adjust temperature, fan speed, and vent mode.
Faults in the control unit or its wiring can prevent commands from reaching the AC system. This can lead to incorrect settings, like turning off the compressor or switching to warm airflow, causing the system to blow warm air despite functioning components.
9. Faulty Sensors
Sensors such as the ambient temperature, evaporator temperature, and AC pressure switch provide data to regulate air conditioning operation.
They do this by monitoring refrigerant pressure levels to protect the air conditioning system. This also ensures the pressure stays within a safe range for compressor operation.
If a sensor sends inaccurate readings, the system may shut down the compressor or prevent cooling to avoid perceived issues. This disrupts the cooling cycle, resulting in warm air output.
10. Faulty Blend Air Door Actuator
The blend door actuator controls the airflow direction between the heater core and evaporator, regulating cabin temperature.
If the actuator fails (due to worn gears or an electrical fault), the blend door may get stuck. This lets warm and cool air mix, causing the car air conditioning to blow warm air even if the refrigerant and compressor are working.
Unsure which of these problems is responsible for your AC issue?
We’ll explain how to determine and fix the problem below.
How to Diagnose and Fix Car AC Problems
Your car’s air conditioning system involves complex electrical, mechanical, and refrigerant components. So, it’s best to have a mechanic handle the car’s AC repair and diagnosis.
Depending on the problem, the mechanic will repair, replace, or clean the related components.
Here’s how they’ll find the issue:
- Check refrigerant levels: Measure the refrigerant pressure using a manifold gauge. If pressure is low, locate the leak with UV dye or an electronic detector.
- Test the fan motor: Check if the blower motor receives power and spins properly.
- Assess the AC compressor: Evaluate the compressor’s functioning with a pressure gauge and conduct a visual inspection.
- Inspect the cabin air filter: Check for a clogged air filter due to dirt or debris buildup.
- Trace electrical issues: Use a multimeter and the car’s wiring diagram to find a blown fuse, broken wire, or any other electrical issue.
- Examine the condenser: Look for physical damage or internal blockage.
- Test the condenser fans: Activate the car air conditioner and check for fan operation. If the fan doesn’t spin, they’ll test the motor and relays.
- Evaluate the AC controls: Test switches, knobs, or digital panels for response and output voltage.
- Check HVAC sensors: Use an OBD II scan tool to read sensor values.
- Test the air pressure switch: Measure continuity and voltage at the switch under different air pressure conditions.
- Check the blend air door actuator: Listen for clicking noises or test actuator movement with a scan tool or manual override.
Still have some questions about your car’s AC system?
We’ll answer them below.
3 FAQs about Car AC Systems
Here’s everything else a car owner should know about AC problems:
1. How Much Does It Cost to Fix Your Car’s Air Conditioning System?
The cost of an AC repair depends on the components that need fixing. Here are some cost estimates to consider (including labor):
- Cabin air filter replacement: $55 to $215
- Climate control unit replacement: $80 to $600
- Electrical repairs: $150 and $500
- Fan motor replacement: $300 and $350
- Pressure switch replacement: $310 and $350
- Blend door actuator replacement: $340 to $410
- Refrigerant leak: $350 and $2,600
- AC condenser leak: $630 to $780
- AC compressor replacement: $810 to $1,210
2. How Long Do Car Air Conditioner Systems Last?
Car air conditioning systems typically last between 10 and 15 years, depending on factors such as maintenance, usage, climate, and vehicle make and model.
3. How Can You Prevent Car AC Problems?
Here are some maintenance practices every car owner should know to prevent an unnecessary AC repair:
- Run the AC regularly to lubricate the compressor and prevent its parts from drying out or seizing.
- Use the defrost mode to remove moisture from the system.
- Check refrigerant levels, as low refrigerant puts extra strain on the compressor.
- Check the front of the radiator area for debris and clean it to prevent a blocked condenser from reducing cooling efficiency.
- Replace the cabin air filter to ensure optimal airflow.
- Have a mechanic inspect the car’s AC system once a year, as early detection of leaks or wear can prevent expensive repairs.
- Monitor unusual smells or noises that could indicate mold in the evaporator or a failing fan motor.
Stay Cool in Your Car with AutoNation Mobile Service
Several issues, from a low refrigerant level to a faulty compressor, can stop your AC from blowing cool air. To find and fix the issue properly, you’ll need professional assistance.
Don’t feel like driving in a car that feels like a sauna?
AutoNation Mobile Service will diagnose and repair your air conditioning system from your driveway. Our technicians are available seven days a week, and every car repair comes with a 12-month | 12,000-mile warranty.
Contact us for a car AC repair and any other vehicle maintenance needs.