NG 900/9-3 AC Recharge

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AC Recharge Overview

If the air from the vents does not seem cold enough but the air conditioning is still working, the A/C may not have been recharged for a long time, or there may be small leaks in the system. Joints between pipes and hoses depend on o-ring seals which often dry out and lose their elastic properties after a few years. For best operation, the system should be evacuated, recharged, and tested for leaks every few years(4-6) by an A/C service professional who can be trusted, but adding refrigerant is a simple process with no special tools required.


While testing the pressure and recharging the AC is an easy job, caution should be exercised. Wear cotton gloves and safety glasses in case refrigerant escapes, and do not attach equipment designed for the low pressure port to the high pressure port.


  • Cotton gloves
  • Eye protection
  • AC Charging gauge
  • AC Refrigerant
    • 900 - r134a refrigerant and PAG-100 oil
    • 9-3 - r134a refrigerant and PAG-46 oil

System Parts

The low pressure port is located next to radiator near the battery. Fig. 1

Fig. 1 - Low Pressure Port

The high pressure port is located behind the grille, and should be avoided. Fig. 2

Fig. 2 - High Pressure Port


Auto part stores sell recharge kits which are basically a hose with two connections and a gauge in the middle. (example, Napa # BK7652982) Our cars use R134a refrigerant, and PAG-100 oil (NG900 w. Seiko-Seiki compressor) or PAG-46 oil (9-3 w. Sanden compressor)

Recharge the system through the low pressure port.

NEVER try to connect a recharge kit to the high-pressure port behind the grille. Fig. 2

It is best to stay away from the high-pressure port completely because of the likelihood of injury if the refrigerant should erupt from that side of the system.

While charging the A/C system, the engine should be running, A/C at the lowest setting and doors or windows should be open. On cars that have ACC the display should read "LO" while charging.

One end of the charging hose snaps over the low pressure port. The other end of the hose screws down tight on top of the refrigerant container. The thumb screw at the container is screwed in to pierce the container seal, and then backed off to allow the refrigerant or the esther oil out. If adding oil, the can is held upside down. If adding refrigerant, right side up. Fig. 3

Fig. 1 - Low Pressure Port With Recharging Equipment Attached