What are the reasons for slow car cooling and insufficient coldness?

[StMaya]

Here are the reasons for slow car cooling and insufficient coldness: 1. Insufficient refrigerant due to low refrigerant levels: The main cause of insufficient refrigerant is usually minor leaks in the system. If there is not enough refrigerant in the air conditioning system, the amount of refrigerant sprayed into the evaporator from the expansion valve will also decrease. As a result, when the refrigerant evaporates in the evaporator, the amount of heat absorbed will decrease, leading to reduced cooling capacity. 2. Presence of water in the air conditioning system: Moisture infiltration in the air conditioning refrigeration system can cause insufficient cooling. There is a component in the refrigeration system called the dryer (or receiver-drier), and one of its main functions is to absorb moisture from the refrigerant to prevent excessive water content in the refrigerant, which would reduce the cooling capacity.

[MaximusLynn]

Last time I took my old ride on a long trip, the AC was gasping for breath like it couldn't catch air. The airflow from the vents was as weak as if it hadn't eaten. Popping the hood revealed the radiator grill completely clogged with willow catkins and dead bugs – it took half an hour of hosing to flush out black muddy water. The veteran mechanic hooked up a pressure gauge to the AC line and said refrigerant had leaked down to half. For refrigerant leaks, focus inspection on pipe connections and condenser joints – any oily residue is a dead giveaway. If the AC completely fails during traffic jams, it's likely either a seized cooling fan or burnt-out blower motor resistor. Another often overlooked spot: when the cabin air filter gets clogged like a honeycomb briquette, cold air can't even reach the interior.

[DeJoseph]

We female car owners often overlook the small details under the windshield—those rows of ventilation slots often get clogged with leaves and small flyers. Last month, I cleared out half a plastic bag of fallen leaves. If the cabin air filter hasn't been changed for six months, the accumulated dust can clog the mesh into felt, naturally reducing airflow. During maintenance, ask the technician to specifically check the expansion valve—last time in my car, it was stuck at the minimum opening, preventing refrigerant flow. Also, remember to turn off the front defroster button when using AC, otherwise all the cold air gets diverted to the windshield. With the intense sun these days, it's best to apply heat-rejecting film on side windows to directly reduce AC workload.

[JosephLynn]

You can diagnose issues by feeling the AC high and low pressure pipes. Normally, the high-pressure pipe should be hot to the touch while the low-pressure pipe feels icy cold. I've encountered situations where the compressor clutch fails to engage—when you turn on the AC and don't hear the clicking sound from the engine bay, there's an 80% chance the electromagnetic coil is dead. The trickiest problem is water contamination in the system. Refrigerant mixed with water can cause the expansion valve to freeze and clog. In such cases, you need to vacuum the system for 48 hours to completely remove the moisture. If the pipes are dented, refrigerant flow will be affected—I've seen cases where an aluminum pipe got crushed by a jack. Remember, in older cars with worn compressors, the cooling effect is particularly poor at idle.

[JoelFitz]

New car owners often make the mistake of temperature settings. Some turn the temperature knob to 25°C but complain the AC isn't cooling. Don't set the fan speed to the lowest setting - when the blower speed is insufficient, the evaporator can frost over. Last time I helped a neighbor check his car, I found his audio system modification had interfered with the alternator wiring, causing voltage fluctuations that made the compressor cycle on and off repeatedly. When parking, don't position the front bumper too close to walls - leave at least half a meter for cooling space. At red lights, it's best to switch to recirculation mode to avoid inhaling exhaust fumes and heated air from vehicles ahead. Remember to use compressed air to clean between radiator fins before each summer.

[DeCalvin]

Vehicles retrofitted with xenon headlights should pay attention to the alternator load, as voltage fluctuations can reduce compressor efficiency. Once, while troubleshooting for a customer, I found that the heater water valve wasn't closing properly, allowing engine hot water to mix into the AC system. Refrigerant charge must strictly follow the vehicle manual—I've seen cases where overfilling actually worsened cooling. Older cars' AC lines slowly leak refrigerant, with an annual normal loss of about 10%. Recently encountered a peculiar case—the Schrader valve's pin was stuck and blocked, such small part failures are most easily overlooked. Nowadays, repair shops commonly use fluorescent leak detectors, which can precisely locate leaks under UV light.