7 Common Car AC Problems and Solutions - Sun Devil Auto

7 Common Car AC Problems and Solutions

common ac problemsIn Arizona, you may use your heater and air conditioner all in the same day just depending on the time. Afternoons can get quite stifling requiring that blast of cool air from your air conditioner. Luckily, this is the time of year that if your AC does go out, it’s not the end of the world. However, you don’t want to be without air conditioning too long because the temperatures will only continue to rise!  Most people are not sure how to diagnose their car’s A/C problems. There are several reasons why your car’s air conditioner may stop working, here are the most common problems and how they can be fixed.

The Air Conditioning system is comprised of many components including a compressor that is driven by the engine; an expansion valve that regulates the flow of refrigerant; and two heat exchangers including the evaporator and condenser. Refrigerant is a fluid that turns into a gas and back to liquid form, flowing throughout the system.

 

Problem: No Cold Air from A/C

 

Most often this issue is caused by a refrigerant leak. Your A/C’s components rely heavily on the refrigerant to cool the vehicle. Without sufficient refrigerant, the other air conditioning components will be unable to function. A leak can occur at any time but most often due to a hole in a connection, hoses, compressor, condenser, or a ruptured evaporator. Unlike an oil leak, unfortunately, refrigerant leaks are difficult to identify. This is because refrigerant is meant to evaporate when exposed to the environment. 

Solution: An expert automotive technician will need to add a fluorescent leak tracer dye and refrigerant to the system. Once added, the technician will run the air conditioning and using a blacklight, will be able to identify the leak to begin repairs and finally perform evacuation and recharge to once again blow cold air.  

 

Problem: No Air Coming From the Vents

 

This issue isn’t as clear cut as hot air coming through the vents. A knowledgeable technician will need to eliminate the possible causes by checking several components first. The technician may begin checking for:

  • A blown fuse or bad relay – If the ventilation fuse blows there will be no power to the blower motor preventing air from blowing through the vents. Likewise, a bad relay can also be the culprit since the relay takes the small electrical current and uses it to regulate the larger current needed for ventilation.  
  • Damage to the blower motor or blower resistor – The blower motor is what pushes the air through the vents in the car, similar to a fan in your home. Blower motors that have malfunctioned due to wear or age will prevent air from coming through the vents. Similarly, the blower resistor works with the blower motor to control the level of how much air is produced to flow through the vents (low, medium, high) based on your preference. 
  • Blocked air intake – Vehicles have two areas where air enters the vehicle. One is where air enters your vehicle through vents by the lower half of the windshield and the other is the air that is recirculated from inside the cabin. If either of the air intake areas is blocked from a clogged filter or other debris, your vents may blow little to no air. 
  • Damaged belts and hoses – The air conditioning system is equipped with many hoses and belts that operate the system. Any sort of leak, detachment, or blockages will prevent proper airflow from the vents.

Solution: Replace fuses and/or the relay, first. If the issue persists, you’ll want to visit an expert A/C Technician to test the other components related to the ventilation system. Repairs or replacement may be required.

 

Problem: Air is Cool But Does Not Get Cold

 

Most often this issue is due to low refrigerant. When there is not enough refrigerant in the system the pressure is reduced which prevents the clutch from triggering the compressor to begin its cycle. If enough refrigerant is in the system it could also be caused by:

  • Blocked or Failed Condenser – The condenser is the device that takes the refrigerant from its gaseous state by removing the heat and transforming it back into a liquid state. If the condenser has a blockage or is otherwise damaged, the air coming through the vents will not be cold.
  • Failed Clutch Switch – If this component is not functioning, the air compressor will be unable to operate, thus preventing it from condensing the liquid refrigerant into gas.

Solution: A technician will need to test these major components to look for blockages, damage, or failure and replace them as necessary.

 

Problem: AC Smells Like Mildew

 

When you turn on your air conditioner and noxious smell of mildew hits your nostrils, it’s because of the growth of bacteria in the system. This is common with vehicles that seldom use A/C, are older, or that frequently use the maximum setting (due to extra moisture in the unit). Bacteria, mold, fungi, and other micro-organisms may develop behind the dashboard on the evaporator. This growth produces a foul odor that comes out of the vents.  

Solution: Air filters can collect dirt, water, dust, and other pollutants and after some time producing an odor. Replacing your air filter will help combat this issue. If replacing the filter does not eradicate the stench, a technician will need to add an anti-bacterial solution into the evaporator area to kill mold and other contaminants from the system.

 

Problem: Car AC Makes Noise When Turned On

 

Anytime your car makes a noise that wasn’t there before could be a sign of trouble. Air conditioning systems are relatively quiet when in use. When you turn on your air conditioning and hear rattling, banging, or other unusual sounds, it’s normal to feel a bit nervous about what is causing the issue. It could be as simple as leaves or other road debris blocking the unit and producing all sorts of unusual noises. It could also indicate a major component could be in failure. If a bearing is worn out the air conditioning will produce a grinding or squealing sound. A rattling sound could indicate the compressor’s clutch has failed. 

Solution: Continuing to use your A/C may only make things worse. Take your vehicle to a trusted technician for inspection. A thorough inspection will be able to determine if a major component is in failure and whether it will need to be replaced.

 

Problem: Water on the Floorboards

 

Bacteria builds up on the air conditioner’s evaporator coil in the A/C heater box located under your dashboard. The bacteria from airflow mixes with the condensation from the coils, creating a slimy film on the A/C fins and producing a moldy smell. After time, the film builds up and can clog the drain line. The drain line is a rubber hose that begins in the evaporator heater box, goes through the floor, and to the undercarriage to remove excess moisture. Once plugged, water from the condensation fills up the heater box and begins dripping out and onto the floor of the vehicle, typically on the passenger side.

Solution: If you notice the floor of your vehicle is damp, don’t hesitate in getting your vehicle to an automotive center for immediate repair. A technician will need to determine what has caused the drain line to become clogged and repair or replace the hose as necessary. 

 

Problem: Air Conditioning Goes from Cold to Hot

 

When you’re driving and the air suddenly goes from comfortably cool to horribly hot, you know there’s a problem. It’s possible that the expansion valve that dispenses the correct amount of refrigerant to the evaporator has failed. A blocked expansion valve prevents the refrigerant from reaching the evaporator and, if moisture is present, causing the valve to freeze. 

Solution: Air conditioning should be cold. If it’s not a certified technician will need to properly test the system’s pressure and inspect components for blockages or malfunctions. 

No matter what symptoms your air conditioning may be experiencing, a qualified automotive technician knows how to properly diagnose car AC problems and how to properly restore your air conditioning’s function. Need service on your car’s A/C? Visit a Sun Devil Auto near you for solutions to all your air conditioning woes.