This seems to be mostly true, but I still don't know how to recharge lr3 air when it is empty of refrigerant
You'll need the following at a minimum:
-A/C valve core tool
-vacuum pump
-manifold gauges
I am not an expert at A/C, but I have done it on my own vehicles several times. Below is how I do it, YMMV.
- Replace the drier in the system
- Connect the BLUE hose to the low side service port. Connect the RED hose to the high side service port. Connect the YELLOW hose to a vacuum pump.
- Open the HIGH and LOW manifold valves using the Red and Blue valves and start the pump. Pull a vacuum on the system for ~30 min.
- Close both valves and turn off the vacuum pump. Let sit under vacuum for another ~30 min. If it holds vacuum for 30 min, then you probably don't have any leaks. release vacuum.
- Find out how much freon/oil your system requires. If you replaced the compressor, follow the manufacturer's instructions, some are pre-oiled. Remove the valve core on the high pressure side. Add the appropriate amount of oil to replace what was lost when you replaced whatever component you had to replace. Reinstall valve core.
- Pull the system into vacuum again and close the high/low valves. Disconnect the YELLOW charging hose from the vacuum pump and connect it to the appropriate refrigerant container.
- Vehicle engine and the A/C system must both be off.
- Make certain that the dispensing valve on the refrigerant source is in the closed position.
- Make certain that both the high pressure and the low pressure valves are in their closed position.
- Open valve on the refrigerant source. Bleed air out of Yellow hose using the vent valve. (you'll need to do this every time you change freon cans if you're using small cans.
- Open the low side valve on the manifold gauge set.
- Charge system until gauges read over 50 pounds of pressure.
- Close dispensing valve and low side valve on the manifold gauge set.
- Start the vehicle. Turn on the A/C and use manual control for "LO" temperature and high fan speed. Rear A/C on manual control to MAX setting
- Open the dispensing valve on the refrigerant source. (Keep the refrigerant source upright at all times so that refrigerant can only enter the hoses as a gas.)
- Open the BLUE low side valve. Allow the gas to flow into the system until the desired amount has been added. Change cans as required, closing the valves before removing the can and purging the yellow line before re-opening the blue valve. RED valve on the manifold stays CLOSED
- When you have charged the system, close the blue valve. Let the compressor run and check the gauge readings to be sure the system is operating properly.
- Disconnect the manifold.
If you are not comfortable doing any of the above, take it to a shop. Most places only charge a couple hours labor + cost of freon to do the job.
