Sometimes, a car's air conditioning system may exhibit low low pressure and high high pressure. There are two common causes for this:
Compressor Displacement Below Requirements
Fault or Damage to the Expansion Valve
Car air conditioning systems have two pressure gauges: one showing high pressure and the other showing low pressure. By checking the values on these gauges, we can determine if the cooling system is functioning correctly. Typically, the normal pressure values for a car air conditioning system are: high pressure between 1.3 to 1.7 MPa, and low pressure between 0.1 to 0.25 MPa. If the values are higher or lower than these ranges, it suggests a potential malfunction, and the car owner should have the issue repaired promptly.
The pressure in the car air conditioning system may change in several ways. The causes and solutions for these changes differ as follows:
1. Low High Pressure, High Low Pressure
When the air conditioning isn't cooling properly, but there's no shortage of refrigerant in the system, you can check if there is a leak inside the compressor. If there's a leak, the compressor needs to be replaced. If the compressor is not the issue, check for a faulty expansion valve. A malfunctioning expansion valve can cause blockages or failure in throttling, which leads to low high pressure and high low pressure. In this case, the expansion valve needs to be replaced.
2. Low Low Pressure, Low High Pressure
The main cause of low low pressure and low high pressure is insufficient refrigerant in the system. This issue typically arises after prolonged use of the air conditioning. If this occurs, the car owner can simply add more refrigerant to the system.
3. High Low Pressure, High High Pressure
This issue is primarily caused by the expansion valve being stuck in the open position. A permanently open expansion valve allows air to enter the cooling system, causing a mixture of high and low pressure, which leads to poor cooling performance. In this case, the expansion valve needs to be replaced promptly.
