May 9, 2022

The 5 Most Common Automotive A/C Problems and Solutions

By Cody Lyons, BG Technical Service Manager

Most car owners are good about regular maintenance such as oil changes, brake pad replacement, and tire rotation. However, the A/C (or climate control system) is frequently overlooked. Neglecting this system can lead to a number of obnoxious noises, smells, or worse—a broken A/C. Below we have described the most common A/C problems and possible solutions to keep your car’s climate control system working properly.

A/C

1. No air blowing from vents

No air exiting the vents is the sign of a blower motor problem. This could be due to a bad fuse or relay, or a faulty blower motor.

If the blower motor is not operating when the A/C is turned on, the fuse and/or relay are the likely cause. If the blower motor comes on but no air is moving through the vents, the air intake and/or filter may be blocked.

2. Air blows, but it isn’t cold

Most often this issue occurs when the refrigerant is low from a possible leak, or there could be another faulty part within the climate control system. A technician will check for leaks using a fluorescent dye, make any necessary repairs, and recharge the system with new refrigerant.

3. Air from A/C stinks

Do you notice a bad, musty smell when you use your A/C? Due to a variety of weather and road conditions, debris and moisture can accumulate in your vehicle’s climate control system. This leads to the growth of bacteria and mold within the ducts, cabin air filter, and evaporator of the system.

A climate control service using an approved disinfectant will kill the germs causing the foul odors in your system. We recommend this service every spring.

4. A/C makes noise when turned on

A properly working climate control system is relatively quiet when in use. If your vehicle makes loud noises when the A/C is turned on, it’s a sign of a problem.

  • Screeching or squealing could be an issue with the A/C compressor belt, a worn out bearing, or possibly a bad pulley.
  • Clicking, knocking, or rattling may indicate compressor clutch failure or possibly loose bolts securing A/C components.
  • Buzzing often occurs when a climate control system is overcharged with refrigerant.
  • Hissing when the vehicle has been turned off, is the result of pressure equalization of the refrigerant. No need to worry about this sound, it is normal.

5. Floorboards are damp

Moisture on the floor of a vehicle is most frequently caused by one of two problems within the climate control system: a heater core leak or clogged evaporator drain hose.

The heater core is usually located under the dashboard on the passenger side of the vehicle. Warm coolant from the engine is circulated through the heater core to warm the passenger compartment when the heater is in use. The heater core can develop a leak that ends up leaving the passenger side floorboard damp and oily from the engine coolant.

More commonly, a wet floorboard is caused by a blockage in the vehicle’s evaporator drain hose. The evaporator is normally found in the same housing as the heater core.

Be Prepared

Repairs to your car’s climate control system will require specific knowledge and specialized tools to complete. Having these issues arise in the heat of the summer can be expensive and time consuming.

Be proactive this spring, and test your A/C early. If you are having any of these problems with your A/C, get it fixed now and avoid the summer rush.

Finally, regular climate control maintenance can prevent many of the above problems and extend the life of your vehicle’s climate control system. Find a BG shop near you and have your A/C serviced every spring.


Cody has more than 14 years of experience in the automotive industry. He has a bachelor’s degree in automotive technology, a master’s degree in business administration, and is ASE Certified. Cody has been with BG for 9 years and is currently the Technical Service Manager.

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