What is the reason for the low-pressure pipe being cold but the interior not cooling down?

[SanJackson]

If the low-pressure pipe is cold, it indicates that the refrigeration is functioning normally. Check if the evaporator filter inside the vehicle is clogged. If it is clogged, it will affect the heat exchange of the evaporator, preventing the heat inside the car from being carried outside by the evaporator. If it's clogged, the cooling capacity will be very low, resulting in the inability to lower the temperature inside the car. Also, check if the car's air recirculation is turned off. If it's turned on, it may also prevent the interior from cooling down. If these checks don't resolve the issue, take the car to a repair shop to check if the air conditioning system's operating pressure is normal. Below are routine checks for air conditioning not cooling: Refrigerant: Check if the system has refrigerant. If not, pressurize the system to check for leaks, then refill it. Compressor: If there is refrigerant, check if the compressor is working. If not, inspect the air conditioning pressure switch, temperature control switch, and their wiring for issues. Heat dissipation: Check the air conditioning's heat dissipation, see if the fan is working. Clean the condenser. Replace the air filter.

[McHailey]

When I find the low-pressure pipe is very cold but the car isn't warm, it's usually because there's something wrong with the air conditioning system. If the refrigerant is insufficient, the low-pressure pipe will be icy, but the evaporator won't cool down properly. If the fan spins too slowly or the air filter is clogged, the heat won't dissipate, making the car feel hot. When I was repairing cars, I encountered this situation, which could also be caused by a stuck temperature valve or the air conditioning condenser not working properly. Don't overlook issues with the ventilation system, such as incorrect settings in recirculation mode, which can lead to poor airflow and lack of cooling. It's best to check the refrigerant pressure and ensure the fan is functioning properly before the peak of summer when driving becomes uncomfortable. Additionally, system icing is a common problem, especially when the air conditioner is turned on and off repeatedly. It's important to get it fixed at a professional shop early to avoid higher costs later.

[GideonDella]

That time I was on a long drive, the low-pressure pipe felt icy to the touch, but the cabin was like a steamer, with very little air coming out of the AC vents. I guessed there might be a bit less refrigerant, causing the pipes to overcool but the car to have no cold air. Another possibility was that the fan motor was broken or the radiator was dirty, preventing cool air from blowing out. Upon checking the AC filter, I found it clogged with dust, blocking the airflow and throwing the AC system's pressure out of balance. This kind of problem is really annoying while driving, especially on the highway, forcing you to pull over and open the windows for air. It's advisable to test the AC's airflow right after starting the car during regular use. If it's not blowing cold air, immediately check the low-pressure pipe situation to prevent battery or alternator issues from affecting the overall voltage. In short, dealing with it early can save a lot of hassle, unlike me who waited until problems arose halfway.

[OBrady]

When the low-pressure pipe feels very cold but the car interior is uncomfortably hot, it's time to systematically check for causes. First, see if the AC fan is running - if the fan stops, cold air won't circulate. Next, check if there's enough refrigerant - low pressure causes excessive pipe cooling but frost on the evaporator surface. Then inspect whether the filter is clean, as blockages prevent airflow. Finally, verify if the temperature sensor is malfunctioning, as false signals can disrupt the AC system. Remember not to tamper with high-pressure components yourself - it's risky. Having a professional test with proper instruments is safest. Regularly cleaning around the fan during car washes can prevent many malfunctions.