How to Recharge Capillary Tube Fitted Auto Air Conditioning Systems

How to Recharge Capillary Tube Fitted Auto AC Systems

The capillary tube is a particular sort of expansion valve in your automotive air conditioning unit. If you are recharging your car's capillary tube air conditioning after having discovered a leak, changing an auto AC part or installing a brand new AC system unit, here is how to do it!

To determine whether you have a capillary tube expansion valve AC: The capillary tube is a section made of material similar to the rest of the air conditioning tubing, but with a small internal diameter and a coil shape.

If you can see this spiral shaped tube, you'll be charging your auto air conditioner from the high side.

• Your first step should be to make sure that you really do need to recharge your refrigerant. Refrigerant is not a consumable -- it doesn't wear out over time. It may leak out, or be discharged when a part is changed or a new system is put in, but overcharging a closed, fully functioning system can actually damage your AC. If you are unsure, check with an auto air conditioning expert.
• Stop the compressor.
• Check which refrigerant is to be used in the system. There may be a specification plate attached to the system. Again, if you are unsure, check with an expert!
• The refrigerant cylinder should be attached to the pressure gauge set at the center manifold hose.
• Throttle the regulator on the gauge and the cylinder's regulator to purge the line of any remaining refrigerant -- this ensures that you aren't overcharging the system, because you know exactly how much gas you’re putting in.
• Take the protective cap off the service valve on your auto air conditioning unit.
• Attach the hose from the plain pressure gauge to the liquid line service valve on your AC.
• Open the regulator on your plain gauge just a little bit, and then throttle the regulator on your refrigerant cylinder.
• When you see that the pressure has reached the desired operating pressure, close the regulator on the cylinder. Close the plain gauge's regulator also.
• Turn your auto AC on to test it. When you do your test run, make sure the sight glass is clear. The subcooling temperature should be around 5.5 degrees Celsius, or about 40 degrees Fahrenheit.
• If your subcooling doesn’t get down to that temperature, repeat the charging process.

Drive away and enjoy the feeling of Alaska inside, and Arizona outside with a fully charged automotive air conditioning unit!