Reasons Why Car Air Conditioning Sometimes Fails to Cool
3 Answers
Car air conditioning may fail to cool due to the following reasons: 1. Insufficient or low refrigerant: When observing from the sight glass on the dryer tank during normal operation, continuous bubbles indicate insufficient refrigerant. If obvious bubble flipping occurs, it signifies severe refrigerant shortage. 2. Excessive refrigerant: Too much refrigerant can also cause cooling failure. The proportion of refrigerant in the air conditioning system must meet specific requirements. An excessive proportion can affect heat dissipation. Similarly, adding too much cooling oil during maintenance can reduce the heat dissipation capacity of the refrigeration system. 3. Loose compressor drive belt: Car refrigeration relies on refrigerant, which is transported by the air conditioning compressor. The drive belt is a crucial moving part that drives the compressor. If the belt is loose, the compressor may slip during operation, reducing transmission efficiency and compressor speed, thereby decreasing refrigerant delivery and resulting in cooling failure. 4. Substandard refrigerant and refrigeration oil: Excessive impurities in the refrigerant and refrigeration oil can clog the car air conditioning filter, leading to cooling failure, increased resistance, and reduced refrigerant flow to the expansion valve, causing insufficient cooling capacity. 5. Moisture infiltration in the refrigeration system: If moisture enters the car air conditioning refrigeration system, it can cause insufficient or no cooling. In such cases, the desiccant or dryer tank in the car air conditioning should be replaced, and the system should be evacuated and recharged with an appropriate amount of new refrigerant.
My old car also experienced intermittent AC issues, and later I found it was mainly caused by refrigerant leaks and cooling problems. Last time at the repair shop, they said the AC pipe connections were loose, causing the refrigerant to slowly leak out, which made the compressor work intermittently. Also, during summer highway driving, the condenser in front of the radiator got clogged with willow catkins, blocking the cooling fins and causing poor heat dissipation, which immediately made the AC stop working. After I cleaned it myself, the situation improved significantly. If you hear a clicking sound when the AC compressor starts, it might be due to poor relay contact, and you’ll need to check under the steering wheel. Always pay attention to the airflow from the vents—if it suddenly gets weaker and then stronger, it’s likely time to replace the filter. Never push through with a failing car AC, especially on the highway, as it can easily lead to accidents.
Nowadays, most car air conditioning issues seem to be maintenance-related, especially concerning the cooling system. My SUV's AC was acting up before - it wouldn't cool at all on hot days but worked fine on cooler days. The dealership found that the cooling fan's speed was unstable, caused by a faulty resistor in the electric fan that made it turn on and off intermittently. There was also air and moisture mixed in the AC lines, resulting in inconsistent cooling performance. The mechanic taught me a trick: after parking, feel if the condenser area at the front is excessively hot to the touch - if it's burning hot, it indicates cooling system problems. Now before every summer, I replace the cabin air filter myself and use compressed air to clean the evaporator core. Haven't had any issues for years. I recommend regularly adding refrigerant oil - it's quite important for compressor protection.
