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

[StRonan]

The possible causes of the fault include compressor failure, insufficient refrigerant, or a stuck-open expansion valve. Below are the specific scenarios: Pressure gauge detects low high pressure and high low pressure in car air conditioning: The cause is compressor failure. If the pressure gauge shows this phenomenon and there is no lack of refrigerant in the pipeline, but the air conditioning performance is poor, then the issue is likely with the air conditioning compressor. There may be internal leakage in the compressor, and generally, replacing the compressor can resolve the problem. Pressure gauge detects low low pressure and low high pressure in car air conditioning: The cause is insufficient refrigerant, which is a common issue. Some older cars may experience refrigerant leakage, and after inspection, simply refilling the refrigerant can solve the problem. Pressure gauge detects high low pressure and high high pressure in car air conditioning: The cause is a stuck-open expansion valve. If the car's cooling is poor and the pressure gauge shows both low and high pressures are elevated, the expansion valve may be stuck open, allowing air into the refrigeration system and mixing high and low pressures, resulting in poor air conditioning cooling performance. Replacing the expansion valve can resolve this issue.

[DePhoebe]

I've encountered this issue of high low pressure and high high pressure in the car AC system before. It might be due to poor heat dissipation from the condenser or a malfunctioning fan that prevents heat from being properly expelled, causing pressure to rise on both sides. Another possibility is overcharging of refrigerant beyond the standard amount or internal system blockages obstructing airflow, which increases the compressor's workload and leads to abnormalities. That time when my car's AC started, the engine noise became louder and there was some shaking, making me worried the engine might stall while driving, so I immediately went to the repair shop. They found that the cooling fan was broken and there was an excessive amount of refrigerant oil added. After replacing the parts, the pressure returned to normal. I'd like to remind you that if the dual high pressure in the AC system isn't repaired promptly, at best it will significantly increase fuel consumption, and at worst, the compressor could be damaged beyond repair, leading to costly replacements. Always pay attention to the heat dissipation condition in the engine compartment while driving to avoid such situations.

[ElisaLynn]

When I was repairing my own car, I found that both the low and high pressures of the AC were abnormally high. Common causes include the condenser being covered with dirt leading to poor heat dissipation, the electric fan being stuck and not spinning, or the refrigerant being overfilled causing excessive pressure in the lines. Checking it yourself is simple: turn off the AC and use a pressure gauge to measure the low and high pressure ports. If the readings exceed the manufacturer's specifications, it might be one of these issues. Clean the radiator fins and fan connector, and use a multimeter to check the circuit to avoid short circuits. After the repair, the pressure stabilized and the AC cooling returned to normal. DIY repairs save money, but safety comes first—wear protective gloves and avoid touching the high-pressure lines as they contain toxic substances. Regularly washing the car to prevent dust buildup in the front grille can help prevent such faults.

[DiJosiah]

High pressure and low pressure in the air conditioning system are common issues, often caused by system blockage or insufficient heat dissipation. In the past, repair shops frequently encountered problems like malfunctioning fans or excessive refrigerant. During summer heat, compressor overload can cause a sudden surge in pressure. Experience suggests promptly checking the condition of the condenser fins and the operation of the fan motor. Neglecting these issues can lead to poor cooling performance and even damage components, resulting in unnecessary expenses. If you notice weak cooling airflow while driving, it's a warning sign to take action.

[LaKate]

Abnormal high and low pressure in the new car's air conditioning system may be caused by cooling system failures such as a dirty condenser, fan stoppage, or internal compressor issues. Use diagnostic tools to read the vehicle's computer for fault codes to confirm. Check if the expansion valve is stuck and the refrigerant balance status to avoid leakage in the high-pressure pipeline. Clean the engine compartment promptly to ensure ventilation and maintain stable pressure for safe driving.

[DeMichael]

My friend's car AC recently had both low and high pressure readings off the charts, resulting in poor cooling and increased fuel consumption. Upon inspection, it was found that the cooling fan motor was burnt out and the condenser was severely clogged with dust, leading to heat dissipation failure and pressure surge. He often drives long distances and didn't pay attention to the engine noise, delaying repairs until the compressor exploded, costing a fortune to replace. The lesson is: if the AC makes abnormal noises or fails to cool properly, immediately stop to check the fan operation and clean the front grille to prevent pressure loss and ensure driving comfort.