Parking Air Conditioner Refrigerant Charging: Official Step-by-Step Guide
As a manufacturer of parking air conditioners and parking heaters, we know that proper refrigerant maintenance is directly tied to cooling performance, service life and operating efficiency of your units. Improper refrigerant charging or skipped leak testing often lead to weak cooling, repeated refrigerant loss and even compressor damage. This official guide walks you through the full standardized process for refrigerant charging, including pipeline replacement, pressure leak detection, vacuum verification and proper refill, so you can restore your parking AC to factory-level performance.
Pre-Work: System Depressurization & Pipeline Replacement
Before any service work, first confirm the system is fully depressurized. Wait until the pressure gauge returns to zero, then begin dismantling AC pipelines and accessories. When replacing old pipelines, pay close attention to the sealing rings. Apply a thin layer of lubricating oil to both sealing rings to reduce friction during installation. Always insert pipelines horizontally and slowly - first the compressor end, then the condenser end. Horizontal installation prevents uneven wear and tearing of sealing rings, which is the most common cause of post-service leaks. Once aligned, tighten all screws and press the platen firmly into place. There must be no gap at the compressor connection; a gap means the screw is not fully tightened and sealing is compromised. Confirm both compressor and condenser connections are gap-free before moving to leak testing.
Step 1: Pressure Leak Detection
Pressure testing is the most reliable way to catch small leaks before refrigerant is added.
Connect the middle tube of the pressure gauge set to a vacuum pump, with the pump exhaust port properly connected.
Open both high and low pressure gauges at the same time to allow simultaneous air intake on both sides.
Power on the pump and charge the system to 18 kg of pressure, with both gauges reaching 18 kg evenly.
Close both pressure gauges simultaneously, then turn off the pump.
Let the system hold pressure for 30 minutes. If the gauge needles drop at all during this time, there is still an air leak in the system, and you must locate and reseal the leak point before proceeding. If both gauges hold steady at 18 kg after 30 minutes, the system is air-tight and ready for vacuuming.
Step 2: Vacuum Leak Verification
Vacuum testing confirms the system can hold negative pressure, which is critical for proper refrigerant operation and prevents moisture from entering the system.
Switch the yellow tube from the pump exhaust to the pump intake port.
Open both high and low pressure gauges again, then power on the vacuum pump.
Run the vacuum until both gauges reach the -1 position, then continue vacuuming for 15 full minutes.
Turn off both gauge switches simultaneously, then power off the pump.
Hold the vacuum for 20 minutes. If both gauge needles remain steady at the -1 position with no movement, the system is fully sealed and has no air leakage. If the pressure rises during the hold period, there is still a leak that must be addressed before refrigerant charging.
Step 3: Refrigerant Charging
Once the system passes both pressure and vacuum leak tests, you are ready to add refrigerant.
Disconnect the yellow tube from the vacuum pump and connect it to a refrigerant bottle opener.
Tighten the connector securely, then turn the knob clockwise to pierce the seal on the refrigerant tank. Turn counterclockwise to retract the piercing needle and allow refrigerant to flow into the tube.
Purge air from the yellow tube by briefly pressing the valve core, to ensure no air enters the AC system.
Open both high and low pressure gauges simultaneously to allow refrigerant to enter the system. Monitor the gauge needles and charge to the specified factory pressure range.
Final Checks & Pro Tips
After charging, run the parking air conditioner on full cooling mode for 10–15 minutes and verify cooling performance is normal. Check all connection points for any signs of refrigerant leakage. For best long-term results, always use the specified refrigerant type for your parking air conditioner model, and never skip leak testing steps. Proper charging not only restores full cooling capacity, but also extends compressor life and reduces long-term maintenance costs for fleets.
As a direct manufacturer, we provide full technical support for all service and maintenance procedures. If you have questions about specific models, refrigerant specifications or bulk service supplies, feel free to reach out to our team.
