What is the optimal pressure for car air conditioning refrigerant recharge?
2 Answers
When recharging refrigerant for car air conditioning, the normal high-pressure range should be 1.3-1.7MPa (13-17kg/cm2 or 190-250Lbf/in2); the normal low-pressure range should be between 0.15-0.25MPa (1.5-2.5kg/cm2 or 20-35Lbf/in2). Additional information: 1. If the low pressure is higher or lower than the normal range, it indicates improper adjustment of the expansion valve. Compressor issues are not included in this category. To measure the high and low pressures of the air conditioning system, the engine should be idling, and measurements should be taken at an ambient temperature of 35℃. 2. When the engine throttle is increased, the measured low pressure should decrease with the engine's RPM—the faster the RPM, the greater (and quicker) the pressure drop. This indicates good compressor performance; otherwise, it suggests a compressor malfunction.
The pressure for recharging car air conditioning refrigerant doesn't have a one-size-fits-all standard—it depends on ambient temperature and AC system design. Having driven for over a decade and done several DIY recharges, I've found the low side should typically be around 25-35 psi, while the high side between 150-230 psi is ideal. For instance, pressures run higher in summer heat and lower in winter, so optimal pressure requires monitoring gauge readings. I always check cooling performance with gauges before recharging—if pressures fall outside this range, the AC won't cool properly and may even damage the compressor. Remember: never overcharge—excessive pressure risks oil leaks from burst components, while insufficient pressure means poor cooling. The best method is to slowly recharge with engine running and AC on until reaching the optimal pressure range. Specific values vary by brand, so consult your vehicle manual. Above all, ensure proper tools and prioritize safety before starting.
