What are the reasons for a car's air conditioner not cooling?

[FinleyFitz]

Reasons for a car's air conditioner not cooling: 1. Blockage in the receiver-drier, expansion valve screen, pipelines, or hoses; 2. Issues with the refrigerant, such as insufficient amount or complete depletion leading to no cooling; 3. The compressor drive belt being too loose, broken, having poor sealing, or the electromagnetic clutch being damaged—a loose belt will slip and fail to transmit power properly; 4. Blown fuse or short circuit in the electrical system; 5. Damage to the blower switch, blower, or other electrical components; 6. The condenser being too dirty—accumulated dust over time reduces cooling efficiency. When using the car's air conditioner, it's important to pay attention to its maintenance. Regularly turning the fan to high speed can help blow out dust from the inner surfaces of the air ducts to prevent blockages.

[LaPiper]

Yesterday, driving in the heat made me sweat profusely, and the air from the AC felt no different than a fan. The most common issue is refrigerant leakage, given the numerous AC pipe joints that can easily leak Freon when they age. A loose compressor belt or a seized compressor can also cause the system to fail—squealing belts are a clear warning sign. It’s also common for the radiator to get clogged with poplar fluff and insect debris; I have to clean it with a pressure washer every spring. If the cabin air filter is as clogged as a rag, cold air won’t blow out at all. If replacing the filter yourself doesn’t fix it, there’s an 80% chance you’ll need to visit a shop to check the system’s pressure.

[OWeston]

Last week when driving my daughter to school, I noticed the AC wasn't cooling properly. Touching the vents revealed warm air. In such cases, the first thing to check is whether the electric fan is running. When I popped the hood, I found the fan was stuck. A condenser clogged with mud can also cause poor heat dissipation - I used a soft brush to clean it and saw improvement. Low refrigerant requires professional refilling; incorrect ratios can actually damage the compressor. A mechanic once taught me to measure vent temperature with a thermometer - below 10°C is normal, but my car measured 15°C which clearly indicates an issue.

[StMary]

My five-year-old car's AC has been underperforming this year. Aside from refrigerant leaks, a stuck expansion valve can affect cooling efficiency. For cars with modified headlights, pay attention to voltage as the compressor clutch may suffer from insufficient power supply. Frozen evaporator coils can also hinder cooling, so the temperature control sensor needs checking. Last time, rodents chewed through my car's AC lines, causing all the refrigerant to leak. Now I make it a habit to regularly check AC pressure with a gauge and seek repairs immediately if readings are abnormal.

[LaBrooklyn]

When taking kids out, I found the AC blowing hot air and almost got heatstroke. This issue is often caused by a clogged condenser, especially when the cooling fins are blocked by willow catkins. A faulty compressor electromagnetic clutch can interrupt power transmission, and a slipping belt may produce squealing noises. If there are oil stains on the refrigerant lines, it usually indicates a leak point. Later, I learned to perform monthly self-checks: start the AC and listen for the compressor's clicking engagement sound, feel the temperature difference between the high and low-pressure pipes, and if the low-pressure pipe isn't cold, take it for repair.

[DiAsher]

Before the rainy season, I noticed a decline in the air conditioning cooling performance. The possible cause could be a saturated and failed dryer bottle, allowing moisture to enter the system and form ice blockages. When the compressor cylinder pressure is insufficient, there will be noticeable metal knocking sounds. A damaged condenser fan resistor can cause the low-speed setting to fail, resulting in loud noise at high speed. I tried DIY leak detection: using a UV light to inspect the pipelines for fluorescent dye leakage points. However, in the end, professional equipment is required to recover the old refrigerant, evacuate the system, and recharge it with the standard amount. Mishandling can damage the entire air conditioning system.