What Causes High Low Pressure and High High Pressure in Car Air Conditioning?

[EmersonAnn]

Here are the specific details: 1. Pressure gauge shows low high pressure and high low pressure in car air conditioning: Cause: Compressor failure. If the pressure gauge displays this phenomenon, there is no shortage of refrigerant in the pipeline, but the air conditioning performance is poor. In this case, the issue may be with the air conditioning compressor, which might have internal leakage. Generally, replacing the compressor can solve the problem. 2. Pressure gauge shows low low pressure and low high pressure in car air conditioning: Cause: Insufficient refrigerant, a common issue. Some older cars may experience refrigerant leakage. After inspection, simply refilling the refrigerant can resolve the issue. 3. Pressure gauge shows high low pressure and high high pressure in car air conditioning: Cause: Faulty expansion valve stuck open. Poor cooling performance in the car, with the pressure gauge indicating both high low pressure and high high pressure, may be due to the expansion valve being stuck open. This can introduce air into the refrigeration system, mixing high and low pressures and reducing air conditioning cooling efficiency. Replacing the expansion valve can solve the problem.

[SanOlivia]

I've experienced the issue where both the low and high pressures of the car's air conditioning system are too high, which resulted in poor cooling performance. The main cause is usually an overcharge of refrigerant, as some mechanics might overfill it to save time, leading to an imbalance in the system's pressure. Additionally, problems with the condenser's heat dissipation are a major factor—such as a broken fan or clogged fins due to leaves and dust, which prevent heat from escaping and cause the high pressure to rise. Internal blockages in the system should not be overlooked either, like a stuck expansion valve or dryer bottle, which restrict refrigerant flow and cause pressure buildup on both sides. During extremely hot weather, high external temperatures increase the AC load, naturally driving up the pressure. Compressor failures, such as leaking or worn valves, can also prevent proper pressure regulation. If left unaddressed, minor issues may lead to poor cooling and increased fuel consumption, while severe cases could result in burst pipes or compressor failure. It's recommended that owners first check if the fan is running and whether the radiator is clean. If the problem persists, they should promptly visit a professional shop to check refrigerant levels and blockages—avoid DIY attempts, as high-pressure lines can be dangerous.