If you live where summers are hot, you know when your air conditioning isn’t working. Sometimes it stops operating entirely, but other times AC can become weaker day by day until you realize it’s at full blast and you’re still sweating. There’s a number of reasons why you might find your car AC blowing air that isn’t cold, and some are an easy fix while others are more complex. Understanding the components of the AC system and checking for the typical issues can help you identify potential problems and ultimately get your AC system functioning as it should again.
Air conditioners (much like refrigerators) operate by pumping a substance called refrigerant through metal tubes. The refrigerant boils and turns to gas at ambient temperatures, absorbing heat from the air — similar to how rubbing alcohol evaporates off your skin at room temperature, making it feel cool. Fans then push the cool air into your cabin.
Over time air conditioning systems lose their refrigerant charge. This can happen in a closed system, or it can be due to a leak. If the system is simply low, it’s an easy fix to add refrigerant, and you can purchase and recharge it yourself at any NAPA Auto Parts store. However, if your system is leaking, you have to find and seal the leak. This is more difficult, and it requires special tools, such as dye and leak detectors.
When you’re recharging or repairing your AC system, you must always take safety precautions, as refrigerant is highly toxic to humans and the environment.
Your vehicle’s AC condenser, which looks like a small radiator, is the coil system through which the refrigerant flows. If the condenser (or really any part of the system) is clogged, the refrigerant won’t flow, which will prevent the cooling that would otherwise result from the refrigerant evaporating into a gas. A fan blows over the condenser to assist the process, so if debris or an electrical problem prevents the fans from operating, this will also cause problems.
Your AC compressor is the pump that keeps refrigerant moving through the system. Without it, you lose your cool air. Identify the compressor under the hood (driven by the serpentine belt with other components in the front of the engine), and listen to hear the clutch “click” on and off while the car is running. If it’s not coming on at all, it may be broken or not receiving power. If it’s kicking on and off rapidly, it might be low on refrigerant.
The blend door directs hot air from your engine into your passenger compartment. If it becomes stuck, you’ll get no cold air, even if your other AC components are working. This problem can be a little difficult to diagnose because the blend door is located far back in and under the dash, a very tough area to reach. Try to listen to hear if the door is shutting, or access it and manually shut it to see if that makes a difference.
Any of the issues involving electrical components could be as simple as a blown fuse, so always start there. AC problems often require more in-depth diagnostics, extensive disassembly and specialized tools, so don’t hesitate to call a professional if you’re left scratching your head. The information here, however, can help you at least get an idea of what’s going wrong before you pay big money at a garage for a complex issue. Whether or not you trust your mechanic, it’s always best to go into any repair situation with some knowledge.
Check out all the air conditioning products available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on car AC, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
Photos courtesy of Blair Lampe.
Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter. In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.