What Causes Normal Low Pressure but High High Pressure in Car Air Conditioning?
2 Answers
The reason for low low pressure and high high pressure in the air conditioning system is poor circulation in the system, blockage in the dryer filter; kinks in the connecting pipes; the shut-off valve not being fully open; or the four-way valve not switching properly. Below are specific details about car air conditioning pressure: 1. Under normal conditions: When the compressor operates at 1500-2000 rpm, the high pressure is around 1.5-2.0 MPa, while the low pressure is around 0.15-0.35 MPa. 2. High ambient temperature around the vehicle: The high pressure may reach around 2.5-2.8 MPa, but it generally does not exceed 3.1 MPa, otherwise it will trigger pressure protection. To ensure the safe operation of the air conditioning compressor, most vehicle air conditioning systems are equipped with a pressure protection switch. When the air conditioning system pressure is too high or too low, the pressure switch will be triggered, stopping the air conditioning compressor.
As someone who has long been helping out at a car dealership, I've found that when a car's air conditioning has normal low pressure but high high pressure, it's mostly a common issue caused by poor condenser heat dissipation. If the condenser is clogged with dust, leaves, or small insects, or if the fan speed slows down or even gets stuck, the high pressure naturally rises. Overcharging the refrigerant can also cause the same problem, increasing the load on the compressor. This is especially noticeable when driving in summer—the AC doesn't cool well and can easily damage parts. Fixing it isn't too hard: first, check if the cooling fins are clean and if the fan is spinning smoothly. If not, clean the condenser surface as soon as possible and check if the refrigerant level is appropriate. Don't delay, or repairs will become more expensive and troublesome.
