Why is the car's air conditioning low-pressure pipe icy but the AC not cooling?
3 Answers
Reasons for the car's air conditioning low-pressure pipe being icy but the AC not cooling include a damaged expansion valve, internal wear of the air conditioning compressor, refrigerant leakage, etc. Detailed explanations of the reasons are as follows: Damaged expansion valve: This prevents the formation of high pressure in the system before the expansion valve, causing the high-pressure refrigerant to fail to reach 150Kpa. As a result, the evaporator after the expansion valve cannot cool down, leading to the AC not cooling. Internal wear of the air conditioning compressor: This results in the pressure between the air conditioning compressor and the expansion valve failing to reach 150Kpa to 200Kpa, preventing the refrigerant in the system from circulating normally and causing the AC not to cool. Refrigerant leakage: If there is too little refrigerant in the air conditioning system, the amount of refrigerant sprayed into the evaporator from the expansion valve will also decrease. Consequently, when the refrigerant evaporates in the evaporator, the amount of heat absorbed will decrease, leading to a reduction in cooling capacity.
I see this situation quite often - the A/C low-pressure pipe feels icy to the touch but the air conditioning isn't cooling properly. This is mostly caused by internal system blockage restricting refrigerant flow. During normal A/C operation, the low-pressure pipe should feel slightly cool, but when it becomes extremely cold, it may indicate a stuck expansion valve or frozen evaporator blocking the air vents. When refrigerant circulation is interrupted, the compressor can't effectively cool the cabin no matter how hard it works. Additionally, insufficient or excessive refrigerant can cause similar issues - too much refrigerant may freeze components while too little results in weak circulation. I recommend first checking if the cabin air filter is dirty and trying a replacement, as dust accumulation can cause uneven heat absorption and ice formation on the evaporator. If this doesn't solve the problem, don't delay - take it to a professional repair shop immediately to check pressure levels and refrigerant purity. Regular A/C maintenance can prevent these minor issues, such as cleaning the filter every six months. Remember, driving safety is crucial in hot weather - don't let A/C failure distract you from the road.
I personally experienced this during a long road trip - the low-pressure AC line felt ice-cold to the touch, yet no cool air came through the vents, which was truly frustrating. After checking, I found the evaporator had frozen over, likely caused by prolonged AC operation with low fan speed or high humidity leading to ice formation. The refrigerant should absorb heat during circulation in the evaporator, but improper flow rates can cause freezing that blocks the air ducts. The solution was turning off the AC to let the system defrost, then restarting with higher fan speed. For long-term prevention, replacing clean filters and maintaining unobstructed airflow is key. Helpful tips include avoiding low fan settings when idling and checking AC settings before summer drives. I've since made it routine to have technicians check refrigerant levels during maintenance to avoid sudden failures. An underperforming AC doesn't just compromise comfort - it forces the engine to work harder and increases fuel consumption, making timely repairs worthwhile.
