How to Recharge Your Vehicle AC

If your vehicle’s AC has has lost its ability to keep you cool, it may simply need a recharge of refrigerant. With a few items from any auto parts store, you should be able to do it yourself.

You will need gloves, eye protection, AC recharge service hose with a pressure gauge, and a can of refrigerant. And maybe a paperclip.

DIY Vehicle AC Recharge

  1. Connect the recharge service hose with pressure gauge and valve to the can of refrigerant.
    1. Twist valve counter clockwise until puncture tip is retracted.
    2. Screw onto the can of refrigerant.
  2. Twist valve clockwise until it punctures the can’s top.
  3. Attach nozzle to the low pressure service fitting on the A/C system. It should only match one fitting.
  4. Turn on the vehicle and set the AC to MAX inside cooling. You should see and hear the compressor engage.
    1. If the compressor does not engage, you may have too little refrigerant in the system which suggests a leak.
    2. If after adding refrigerant, the compressor still does not engage, you may have a bad compressor or relay.
    3. You can bypass the relay with a jumper wire to test the compressor.
  5. While watching the pressure gauge, slowly twist the valve and allow the refrigerant to enter the system. This make take up to 10 or 15 minutes.
  6. Feel the air at the vents. It should be getting cold.
  7. Once you have reached the proper pressure level for the ambient temperature or all the refrigerant has left the can, twist the valve counter clockwise to close it.
  8. Remove the recharge service hose from the low pressure service fitting. If you used a jumper in step 4, remove it, too.

Get a Pro

Not every vehicle AC problem can be tackled by an amateur. Some problems will need training, experience, fancy tools, and sometimes parts.

  • If your car is earlier than approximately 1993, the air conditioning will operate on the now obsolete R12.
  • If your system is completely discharged, it may be contaminated with moisture. A pro will fix the leak and remove the moisture with a vacuum pump — a process that takes about an hour.
  • If your AC turns warm weeks or months after charging, a pro will track down the leak and replace the part and seals.
  • If a part needs to be replaced. Apart from fuses and relays, leave the big items to a professional who will have the proper tools.