Excessive refrigerant, air entering the refrigeration system, or insufficient cooling due to condenser failure can all cause dual high pressure in car air conditioning. The reasons for high pressure in car air conditioning can be analyzed in two scenarios: 1. If both high and low pressure values are too high, the possible causes are as follows: First, there may be air in the system, requiring a complete evacuation and recharge of refrigerant. Second, the system may be blocked, often due to a clogged or malfunctioning expansion valve, which should be replaced. Third, excessive refrigerant may be present, indicated by the exhaust port feeling 'hot' and the suction port feeling 'warm'—normally, these should feel 'cool.' The compressor may also produce liquid hammering sounds, necessitating a complete evacuation and precise refrigerant recharge. Fourth, poor condenser cooling may be the issue, with the pipeline from the condenser outlet to the expansion valve inlet feeling 'hot'—normally, it should feel 'warm.' The solution is to clean the condenser and radiator grille or replace them if necessary. Fifth, the expansion valve may be faulty, indicated by heavy condensation or frost on the low-pressure pipe. Check if the expansion valve is installed correctly and replace it if necessary. Sixth, other faults such as cooling fan failure, engine overheating, or excessive or insufficient lubricating oil may be the cause. 2. If the high-pressure value is too high and the low-pressure value is too low, there are two possibilities: First, the expansion valve may be clogged due to contaminants from a failed liquid storage dryer. Second, the power element may have failed, often because the sensing bulb has leaked, keeping the valve closed. The solution is to replace the expansion valve and the liquid storage dryer.
