Reasons for Frozen Car AC Pipes but No Cool Air Output
2 Answers
When water enters the AC pipes, it can freeze and cause an ice blockage, preventing the refrigerant from circulating in the AC system. The refrigerant in the low-pressure section of a car's AC system has a very low temperature and freezing point, so it doesn't freeze inside the system. The refrigerant absorbs heat in the low-pressure section, creating a cooling effect. However, water freezes at 0 degrees Celsius, leading to ice formation. Related information: 1. Types of car AC systems: Integrated heating and cooling AC systems, where components like the evaporator, heater core, centrifugal blower, and control mechanism are assembled together, known as the AC unit assembly. 2. AC compression: The compressor draws in low-temperature, low-pressure refrigerant gas from the evaporator outlet and compresses it into high-temperature, high-pressure gas before discharging it. 3. AC heat dissipation: High-temperature, high-pressure refrigerant gas enters the condenser, where it condenses into a liquid due to reduced pressure and temperature, releasing a significant amount of heat. 4. AC throttling: High-temperature and high-pressure refrigerant liquid expands after passing through the expansion device, causing a sharp drop in pressure and temperature, and is discharged as a mist.
Last time I encountered the issue of the AC pipe freezing up and not cooling, I found out it was due to insufficient refrigerant. The low-pressure pipe froze but the vents blew hot air because abnormal system pressure caused the evaporator to freeze and block the air duct. It's also necessary to check the temperature sensor—sometimes when it fails, it makes the compressor work continuously, overcooling. The most easily overlooked part is the AC filter; if it hasn't been replaced in two years, the dust buildup can block it completely, preventing cold air from coming out. Whatever you do, don’t try to dismantle it yourself. I ended up having a mechanic use a pressure gauge to check the refrigerant pressure and replace the filter to fix it. Thinking back now, suffering in that sauna-like car during the hot weather was really miserable.
